Getting Past the “Entrepreneurial Growth Ceiling”: A Longitudinal Study of IPO Firm Growth Through Solution Driven Strategies

In this paper we introduce a concept that we call the Entrepreneurial Growth Ceiling (EGC). We develop arguments that new venture IPOs hit the EGC prior to their IPO, and the ceiling is part of the impetus for going public. The EGC represents a set of problems, and we hypothesize that a firm’s ability to break through the ceiling quickly (within a year following the IPO) is critical for long-term performance. We argue that proceeds from the IPO will aid firms in breaking through the ceiling if the proceeds are strategically allocated. Results indicate firms that allocate proceeds to human resources and research and development (R&D) resources are more likely to break through the EGC quickly and enhance long-term stock performance

Life prediction and constitutive models for engine hot section anisotropic materials program

This report presents the results from a 35 month period of a program designed to develop generic constitutive and life prediction approaches and models for nickel-based single crystal gas turbine airfoils. The program is composed of a base program and an optional program. The base program addresses the high temperature coated single crystal regime above the airfoil root platform. The optional program investigates the low temperature uncoated single crystal regime below the airfoil root platform including the notched conditions of the airfoil attachment. Both base and option programs involve experimental and analytical efforts. Results from uniaxial constitutive and fatigue life experiments of coated and uncoated PWA 1480 single crystal material form the basis for the analytical modeling effort. Four single crystal primary orientations were used in the experiments: (001), (011), (111), and (213). Specific secondary orientations were also selected for the notched experiments in the optional program. Constitutive models for an overlay coating and PWA 1480 single crystal material were developed based on isothermal hysteresis loop data and verified using thermomechanical (TMF) hysteresis loop data. A fatigue life approach and life models were selected for TMF crack initiation of coated PWA 1480. An initial life model used to correlate smooth and notched fatigue data obtained in the option program shows promise. Computer software incorporating the overlay coating and PWA 1480 constitutive models was developed

Rotational properties of two-component Bose gases in the lowest Landau level

We study the rotational (yrast) spectra of dilute two-component atomic Bose gases in the low angular momentum regime, assuming equal interspecies and intraspecies interaction. Our analysis employs the composite fermion (CF) approach including a pseudospin degree of freedom. While the CF approach is not {\it a priori} expected to work well in this angular momentum regime, we show that composite fermion diagonalization gives remarkably accurate approximations to low energy states in the spectra. For angular momenta $0 < L < M$ (where $N$ and $M$ denote the numbers of particles of the two species, and $M \geq N$), we find that the CF states span the full Hilbert space and provide a convenient set of basis states which, by construction, are eigenstates of the symmetries of the Hamiltonian. Within this CF basis, we identify a subset of the basis states with the lowest $\Lambda$-level kinetic energy. Diagonalization within this significally smaller subspace constitutes a major computational simplification and provides very close approximations to ground states and a number of low-lying states within each pseudospin and angular momentum channel

Majoron emission in muon and tau decays revisited

In models where the breaking of lepton number is spontaneous a massless Goldstone boson, the Majoron ($J$), appears. We calculate the theoretically allowed range for the branching ratios of Majoron emitting charged lepton decays, such as Br($\mu \to e J$) and Br($\mu \to e J \gamma$), in a supersymmetric model with spontaneous breaking of R-parity. Br($\mu\to eJ$) is maximal in the same region of parameter space for which the lightest neutralino decays mainly invisibly. A measurement of Br($\mu\to eJ$) thus potentially provides information on R-parity violation complementary to accelerator searches. We also briefly discuss existing bounds and prospects for future improvements on the Majoron coupling to charged leptons.Comment: 9 pages, 4 figure

Notched fatigue of single crystal PWA 1480 at turbine attachment temperatures

The focus is on the lower temperature, uncoated and notched features of gas turbine blades. Constitutive and fatigue life prediction models applicable to these regions are being developed. Fatigue results are presented which were obtained thus far. Fatigue tests are being conducted on PWA 1480 single crystal material using smooth strain controlled specimens and three different notched specimens. Isothermal fatigue tests were conducted at 1200, 1400, and 1600 F. The bulk of the tests were conducted at 1200 F. The strain controlled tests were conducted at 0.4 percent per second strain rate and the notched tests were cycled at 1.0 cycle per second. A clear orientation dependence is observed in the smooth strain controlled fatigue results. The fatigue lifes of the thin, mild notched specimens agree fairly well with this smooth data when elastic stress range is used as a correlating parameter. Finite element analyses were used to calculate notch stresses. Fatigue testing will continue to further explore the trends observed thus far. Constitutive and life prediction models are being developed

Life prediction and constitutive models for engine hot section

The purpose of this program is to develop life prediction models for coated anisotropic materials used in gas turbine airfoils. In the program, two single crystal alloys and two coatings are being tested. These include PWA 1480, Alloy 185, overlay coating (PWA 286), and aluminide coating (PWA 273). Constitutive models are also being developed for these materials to predict the time independent (plastic) and time dependent (creep) strain histories of the materials in the lab tests and for actual design conditions. This nonlinear material behavior is particularly important for high temperature gas turbine applications and is basic to any life prediction system. Some of the accomplishments of the program are highlighted