In graph theory, as in many fields of mathematics, one is often interested in finding the maxima or minima of certain functions and identifying the points of optimality. We consider a variety of functions on graphs and hypegraphs and determine the structures that optimize them. A central problem in extremal (hyper)graph theory is that of finding the maximum number of edges in a (hyper)graph tha...

Venture capital (VC) is a relatively recent addition to the US national system of innovation (NSI). Tracing the history of the VC industry in the US provides an interesting example of how NSIs can add new institutions, and in the process be transformed. The history encompasses important exogenous events, endogenous developments, and actions by individual actors. The story of the development of ...

We consider a general multiobjective optimization problem with five basic optimality principles: efficiency, weak and proper Pareto optimality, strong efficiency and lexicographic optimality. We generalize the concept of tradeoff directions defining them as some optimal surface of appropriate cones. In convex optimization, the contingent cone can be used for all optimality principles except lex...

Introduction: Renal ischemia/reperfusion (I/R) injury due to reactive oxygen species (ROS) formation is the main cause of acute kidney damage. Nitric oxide (NO) biosynthesis and oxidative stress are closely related to the pathogenesis of renal I/R injury. This study was undertaken to determine the effects of L-arginine (L-arg) as NO donor and aerobic exercise (EX) and also the combination of L-...

This paper presents a voltage stability constrained optimal power flow that is expressed via a bilevel programming framework. The inner objective function is dedicated for maximizing voltage stability margin while the outer objective function is focused on minimization of total production cost of thermal units. The original two stage problem is converted to a single level optimization problem v...

This paper develops a method for nodal pricing and market clearing mechanism considering reliability of the system. The effects of components reliability on electricity price, market participants’ profit and system social welfare is considered. This paper considers reliability both for evaluation of market participant’s optimality as well as for fair pricing and market clearing mechanism. To ac...

background: to evaluate the effect of exendine-4 (ex-4), a glucagon-like peptide 1 (glp-1) receptor agonist, on the differentiation of insulin-secreting cells (ipcs) from rat adipose-derived mesenchymal stem cells(admscs). materials and methods: in this experimental study, admscs were isolated from rat adipose tissue and exposed to induction media with or without ex-4. after induction, the exis...

Institutions, Markets and Men’s and Women’s Wage Inequality: Evidence from Ukraine ∗ Ukraine, the second largest country in the former Soviet bloc, is facing the challenge of rallying popular support for major structural reforms. As in most developing economies, the “Orange Revolution” government’s success will depend on its ability to keep income distribution within an acceptable range. This p...