Entrepreneurship as a Key Resolution for Declining Business Dynamism

This paper investigates the causes and effects of declining business dynamism in the United States and identifies potential solutions that can be utilized to stimulate business dynamism through a comprehensive literature review. While the main focus of this paper is on business dynamism, the research also addresses entrepreneurial challenges and incentives, since active entrepreneurial activity is critical to maintaining a dynamic business environment. The study explores six factors—insufficient access to capital, regulations and tax compliance, employee/employer mismatch, economic uncertainty, generational views of entrepreneurship, and effects of corporations and other large enterprises—that influence entrepreneurial activity

Interactions between leukocytes, platelets and the endothelium in vein graft failure

Autologous venous grafts are preferred conduits in bypass surgery due to their length, easy harvesting, and feasibility. However, development of intimal hyperplasia decreases long-term patency rate in venous grafts prompting close clinical surveillance and further intervention. Mechanical forces, inflammation, and shear stress responses in venous grafts after surgical transfer may be involved in the development of intimal hyperplasia. This thesis focuses on inflammatory reactions in venous grafts. We hypothesized that interactions between leukocytes, platelets and endothelial cells induce intimal hyperplasia resulting in venous graft failure. We demonstrate that VGs obtained by end-to-end anastomosis of the inferior vena cava (IVC) from donor mice grafted to the abdominal aorta in recipients suffer extensive endothelial injury, platelet deposition and leukocyte invasion early after grafting. Re-endothelialization of interposed venous grafts was completed after 4 weeks. Regenerated endothelium displayed normal resistance to recruitment of leukocytes. Thus, we found that there is a time window during the first weeks following grafting in which venous grafts are susceptible to vessel injury and inflammation. Leukocyte recruitment on inflammatory endothelium initiates with margination, capture followed by rolling, firm adhesion and transmigration. We hypothesized that absence or functionblockage of leukocyte adhesion molecules P-selectin and E-selectin that are important for rolling may influence development of intimal hyperplasia in venous grafts by reduction of the recruitment of leukocytes. Indeed, intimal hyperplasia was significantly reduced in E- and P-selectin double deficient mice compared to WT both at 28 days and 63 days after VG transfer. This was paralleled by a reduction in the recruitment of leukocytes to the graft wall. Similar findings were made in WT mice treated with a combination of function-blocking antibodies against P- and E-selectin. The effect of P-selectin alone was addressed using P-selectin deficient mice. We found that intimal hyperplasia was significantly attenuated in mice deficient in P-selectin compared to WT mice 28 days after surgery concomitant with decreased leukocyte invasion. Interestingly, single-dose blockage of P-selectin or its leukocytic ligand PSGL-1 at the time of surgery could block the function of these molecules for up to 10 days and reduced later formation of intimal hyperplasia. Hence, early inhibition of these molecules has potential therapeutic effects on long-term vein graft failure. Platelets strongly influence haemostasis, inflammation and tissue regeneration after vascular injury, which are all represented in the period of re-endothelialization after venous graft transfer. We tested whether absence or function-blockage of platelets could influence intimal hyperplasia in venous grafts. We first used antiserum depletion of platelets for 12 days following surgical grafting. Indeed, IH and leukocyte invasion were reduced in platelet-depleted mice. Moreover, inhibition of integrin αIIbβ3, the main aggregation receptor on platelets, also reduced IH and leukocyte recruitment in the graft wall. The reduction of intimal hyperplasia in mice treated with the antibody against integrin αIIbβ3 was paralleled by radical reductions of the number of adherent platelets and leukocytes on the luminal surface of grafts one hour following grafting. In summary, our work emphasizes the role of interactions between leukocytes, platelets and the vessel wall in venous grafts during their adaptation to the arterial circulation. These mechanisms constitute attractive targets for the development of further preventive pharmacological strategies against vein graft failure

Error Structure of Randomized Design Under Background Correlation with a Missing Value

The analysis of variance technique is probably the most popular statistical technique used for testing hypotheses and estimating parameters. Eisenhart presents two classes of problems solvable by the analysis of variance and the assumption underlying each class. Cochran lists the assumptions and also discusses the consequences when these assumptions are not met. It is evident that if all the assumptions are not satisfied, the confidence placed in any result obtained in this manner is adversely affected to varying degrees according to the extent of the violation. One of the assumptions in the analysis of variance procedures is that of uncorrelated errors. The experimenter may not always meet this conditions because of economical or environmental reasons. In fact, Wilk questions the validity of the assumption of uncorrelated errors in any physical situation. For example, consider an experiment over a sequence of years. A correlation due to years may exist, no matter what randomization technique is used, because the outcome of the previous year determines to a great extent the outcome of this year. Another example would be the case of selecting experimental units from the same source, such as, sampling students with the same background or selecting units from the same production process. This points out the fact that the condition such as background, or a defect in the production process may have forced a correlation among the experimental units. Problems of this nature frequently occur in Industrial, Biological, and Psychological experiments

Development of Synthetic Pathways for Macrocyclic Acetylenes

A synthetic sequence was developed for the preparation of a diindeno-fused 4Hcyclopenta[def] phenanthrene derivative containing two bromo substituents as a potential building block for the construction of macrocyclic acetylenes. The synthetic sequence required the preparation of a benzannulated enediyne, 1-bromo-2-ethynyl-3-(2- phenylethynyl)benzene. The Sonogashira reaction between 1,3-dibromo-2-iodobenzene and (trimethylsilyl)ethyne produced I ,3-dibromo-2-[(trimethylsilyl)ethynyl]benzene. Metalhalogen exchange with n-butyllithium followed by iodination with iodine furnished 1-bromo- 3-iodo-2-[(trimethylsilyl)ethynyl]benzene. A second Sonogashira reaction with phenylethyne followed by desilylation then furnished 1-bromo-2-ethynyl-3-(2-phenylethynyl)benzene.;Treatment of an excess of 1-bromo-2-ethynyl-3-(2-phenylethynyl)benzene with lithium diisopropylamide followed by condensation with 2,2-dimethoxy-1 ,3-indandione furnished the corresponding propargylic diol as the major adduct and the corresponding mono-ol as the minor adduct. On exposure to thionyl chloride, the diol underwent a Schmittel cascade cyclization reaction to produce the diindeno-fused 4H-cyclopenta[def]phenanthrene derivative containing two bromo substituents. The presence of the two bromo substituents provides handles for additional Sonogashira reactions for the construction of macrocyclic acetylenes

Autonomous Recharging and Flight Mission Planning for Battery-operated Autonomous Drones

Autonomous drones (also known as unmanned aerial vehicles) are increasingly popular for diverse applications of light-weight delivery and as substitutions of manned operations in remote locations. The computing systems for drones are becoming a new venue for research in cyber-physical systems. Autonomous drones require integrated intelligent decision systems to control and manage their flight missions in the absence of human operators. One of the most crucial aspects of drone mission control and management is related to the optimization of battery lifetime. Typical drones are powered by on-board batteries, with limited capacity. But drones are expected to carry out long missions. Thus, a fully automated management system that can optimize the operations of battery-operated autonomous drones to extend their operation time is highly desirable. This paper presents several contributions to automated management systems for battery-operated drones: (1) We conduct empirical studies to model the battery performance of drones, considering various flight scenarios. (2) We study a joint problem of flight mission planning and recharging optimization for drones with an objective to complete a tour mission for a set of sites of interest in the shortest time. This problem captures diverse applications of delivery and remote operations by drones. (3) We present algorithms for solving the problem of flight mission planning and recharging optimization. We implemented our algorithms in a drone management system, which supports real-time flight path tracking and re-computation in dynamic environments. We evaluated the results of our algorithms using data from empirical studies. (4) To allow fully autonomous recharging of drones, we also develop a robotic charging system prototype that can recharge drones autonomously by our drone management system