Natural Selection, Irrationality and Monopolistic Competition

This paper builds an evolutionary model of an industry where firms produce differentiated products. Firms have different average cost functions and different demand functions. Firms are assumed to be totally irrational in the sense that firms enter the industry regardless of the existence of profits; firms' outputs are randomly determined rather than generated from profit maximization problems; and firms exit the industry if their wealth is negative. It shows that without purposive profit maximization assumption, monopolistic competition still evolves in the long run. The only long run survivors are those that possess the most efficient technology, face the most favorable market conditions and produce at their profit maximizing outputs. This paper modifies and supports the classic argument for the derivation of monopolistic competition.Evolution, Natural Selection, Irrationality, Monopolistic Competition, Survival of the Fittest, Market Rationality

Adaptation and survival in new businesses: Understanding the moderating effects of (in)dependence and industry.

New ventures as well as new business units experience significant difficulties in finding a viable market application or business model. They often need to adapt their initial business model and this need for adaptation is mainly due to high degrees of uncertainty and ambiguity they are confronted with. This paper hypothesizes that adaptation is crucial for new ventures' and new business units' survival, but that differences exist between the need for adaptation in business units of established companies versus in independent start-ups. According to insights obtained from institutional isomorphism as well as from the resource-based theory of the firm, the effects of adaptation on survival are complex and multifaceted. We test the adaptation-survival hypothesis through a survival analysis of a sample of 117 new ventures and new business units. We find that the main effect of adaptation on survival is negative, but that this effect is moderated and even reversed by the (in) dependence of the new business and by the industry in which it is active.Innovation; Research; Model; Companies; Performance; Startups; Processes; Factors; Effects; Industry; Market; Uncertainty; Theory; Dependence;

On the Lagrangian Dynamics of Atmospheric Zonal Jets and the Permeability of the Stratospheric Polar Vortex

The Lagrangian dynamics of zonal jets in the atmosphere are considered, with particular attention paid to explaining why, under commonly encountered conditions, zonal jets serve as barriers to meridional transport. The velocity field is assumed to be two-dimensional and incompressible, and composed of a steady zonal flow with an isolated maximum (a zonal jet) on which two or more travelling Rossby waves are superimposed. The associated Lagrangian motion is studied with the aid of KAM (Kolmogorov--Arnold--Moser) theory, including nontrivial extensions of well-known results. These extensions include applicability of the theory when the usual statements of nondegeneracy are violated, and applicability of the theory to multiply periodic systems, including the absence of Arnold diffusion in such systems. These results, together with numerical simulations based on a model system, provide an explanation of the mechanism by which zonal jets serve as barriers to meridional transport of passive tracers under commonly encountered conditions. Causes for the breakdown of such a barrier are discussed. It is argued that a barrier of this type accounts for the sharp boundary of the Antarctic ozone hole at the perimeter of the stratospheric polar vortex in the austral spring.Comment: Submitted to Journal of the Atmospheric Science

Determination of Frequency and Distribution of Hessian Fly (Diptera: Cecidomyiidae) Biotypes in the Northeastern Soft Wheat Region

Fifteen collections of Hessian flies from the northern soft winter wheat region of the United States were used to determine the composition and frequency of biotypes. The wheat cultivars \u27Seneca\u27 (H7Hs), \u27Monon\u27 (H3), \u27Knox 62\u27 (~, H7Hg), and \u27Abe\u27 (Hs) were used as differentials. Biotypes J and L replaced biotype B as the prevalent biotype in Indiana, since wheat cultivars having the Hs and the H6 genes have been grown. Biotype GP, the least virulent of any Hessian fly biotypes, was still present in New York indicating that wheat cuItivars with no genes for resistance are still being grown there. The genetic variability of Hessian fly biotypes that enables them to overcome the resistance in wheat cultivars is discussed

Clustering, advection and patterns in a model of population dynamics with neighborhood-dependent rates

We introduce a simple model of population dynamics which considers birth and death rates for every individual that depend on the number of particles in its neighborhood. The model shows an inhomogeneous quasistationary pattern with many different clusters of particles. We derive the equation for the macroscopic density of particles, perform a linear stability analysis on it, and show that there is a finite-wavelength instability leading to pattern formation. This is the responsible for the approximate periodicity with which the clusters of particles arrange in the microscopic model. In addition, we consider the population when immersed in a fluid medium and analyze the influence of advection on global properties of the model.Comment: Some typos and some problems with the figures correcte

New ventures on the search for viable business models: Taking into account levels of uncertainty / ambiguity.

There exists evidence that most initial selections of business models by new ventures have to be adapted later on and that minor this need for adaptation stems from the high degrees of uncertainty and ambiguity new ventures are confronted with, both on the technology and the market level. The main research question of this paper is whether different levels of uncertainty and ambiguity have an effect on the appropriateness of different search strategies new ventures can use to adapt their business model; and if yes, what this effect is. We first present the relevant literature. We then put forward a simulation model - based on the model developed by Kauffman (1989, 1993) - as a formal basis for addressing our research question and analyze the simulation results. To conclude, these results are discussed in the light of existing research on entrepreneurship and innovation and some limitations of our research methodology are presented.Innovation; Market; Model; Models; Research; Selection; Simulation; Strategy; Technology; Uncertainty;

Simultaneous Parasitism of Field-Collected Green Cloverworm, \u3ci\u3eHypena Scabra\u3c/i\u3e (Lepidoptera: Noctuidae) Larvae by Endoparasitioids and an Entomopathogenic Fungus

The impacts of entomopathogens (e.g., fungi, bacteria, protists and viruses) on larval Lepidoptera and their associated insect parasitoids have been examined in laboratory studies but field studies of interaction between these two mortality factors are rare. We present field observations of concurrent insect parasitism and fungal disease infection in larvae of the green cloverworm, Hypena scabra, a sporadic pest of soybean (Glycine max) in North America. We reared ten parasitoid species from H. scabra larvae during our three-month study. Three parasitoid species were dominant and overlapped the period of infection by the entomopathogenic fungus Nomuraea rileyi: Aleiodes nolophanae, Cotesia plathypenae and Campylochaeta plathypenae. Two of the three parasitoid species, Co. plathypenae and Ca. plathypenae, completed development within H. scabra larvae infected by N. rileyi. Overall incidence of simultaneous parasitism and fungal infection was low, averaging 6.7% of H. scabra larvae parasitized by Ca. plathypenae and 3.3% of those parasitized by Co. plathypenae