Models that depict innovation as a smooth, well-behaved linear process badly misspecify the nature and direction of the causal factors at work. Innovation is complex, uncertain, somewhat disorderly, and subject to changes of many sorts. Innovation is also difficult to measure and demands close coordination of adequate technical knowledge and excellent market judgment in order to satisfy economic, technological, and other types of constraints—all simultaneously. The process of innovation must be viewed as a series of changes in a complete system not only of hardware, but also of market environment, production facilities and knowledge, and the social contexts of the innovation organization.

An Overview of Innovation

The Auger recombination coefficient in quasi-bulk InxGa1−xN (x∼9%–15%) layers grown on GaN (0001) is measured by a photoluminescence technique. The samples vary in InN composition, thickness, and threading dislocation density. Throughout this sample set, the measured Auger coefficient ranges from 1.4×10−30to2.0×10−30cm6s−1. The authors argue that an Auger coefficient of this magnitude, combined with the high carrier densities reached in blue and green InGaN∕GaN (0001) quantum well light-emitting diodes (LEDs), is the reason why the maximum external quantum efficiency in these devices is observed at very low current densities. Thus, Auger recombination is the primary nonradiative path for carriers at typical LED operating currents and is the reason behind the drop in efficiency with increasing current even under room-temperature (short-pulsed, low-duty-factor) injection conditions.

Auger recombination in InGaN measured by photoluminescence

Bose–Einstein condensation (BEC), a form of matter first postulated in 1924, has famously been demonstrated in dilute atomic gases at ultra-low temperatures. Much effort is now being devoted to exploring solid-state systems in which BEC can occur. In theory semiconductor microcavities, where photons are confined and coupled to electronic excitations leading to the creation of polaritons, could allow BEC at standard cryogenic temperatures. Kasprzak et al. now present experiments in which polaritons are excited in such a microcavity. Above a critical polariton density, spontaneous onset of a macroscopic quantum phase occurs, indicating a solid-state BEC. BEC should also be possible at higher temperatures if coupling of light with solid excitations is sufficiently strong. Demokritov et al. have achieved just that, BEC at room temperature in a gas of magnons, which are a type of magnetic excitation. Bose–Einstein condensation, the formation of a collective quantum state of identical particles, called bosons, is observed at room temperature in a gas of magnons, which are a type of magnetic excitation. Bose–Einstein condensation1,2 is one of the most fascinating phenomena predicted by quantum mechanics. It involves the formation of a collective quantum state composed of identical particles with integer angular momentum (bosons), if the particle density exceeds a critical value. To achieve Bose–Einstein condensation, one can either decrease the temperature or increase the density of bosons. It has been predicted3,4 that a quasi-equilibrium system of bosons could undergo Bose–Einstein condensation even at relatively high temperatures, if the flow rate of energy pumped into the system exceeds a critical value. Here we report the observation of Bose–Einstein condensation in a gas of magnons at room temperature. Magnons are the quanta of magnetic excitations in a magnetically ordered ensemble of magnetic moments. In thermal equilibrium, they can be described by Bose–Einstein statistics with zero chemical potential and a temperature-dependent density. In the experiments presented here, we show that by using a technique of microwave pumping it is possible to excite additional magnons and to create a gas of quasi-equilibrium magnons with a non-zero chemical potential. With increasing pumping intensity, the chemical potential reaches the energy of the lowest magnon state, and a Bose condensate of magnons is formed.

Bose–Einstein condensation of quasi-equilibrium magnons at room temperature under pumping

When a gas of bosonic particles is cooled below a critical temperature, it condenses into a Bose-Ei…

Bose-Einstein condensation

Chemical Science Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352; Department of Chemistry, ShelbyHall, University of Alabama, Box 870336, Tuscaloosa, Alabama 35487-0336; Notre Dame Radiation Laboratory, University of Notre Dame,Notre Dame, Indiana 46556; Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 0520-8107; Argonne NationalLaboratory, 9700 South Cass Avenue, Argonne, Illinois 60439; Department of Computer Science and Department of Physics, 2710 University Drive,Washington State University, Richland, Washington 99352-1671; Lawrence Berkeley National Laboratory, 1 Cyclotron Road Mailstop 1-0472,Berkeley, California 94720; Department of Chemistry and Biochemistry, University of Texas at Austin, 1 University Station A5300,Austin, Texas 78712; Office of Basic Energy Sciences, U.S. Department of Energy, SC-141/Germantown Building, 1000 Independence Avenue,S.W., Washington, D.C. 20585-1290; Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson,Hoboken, New Jersey 07030; Department of Chemistry, Johns Hopkins University, 34th and Charles Streets, Baltimore, Maryland 21218;Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062; Department of Chemistry, The Ohio StateUniversity, 100 West 18th Avenue, Columbus, Ohio 43210-1185; Department of Chemistry, Columbia University, Box 3107, Havemeyer Hall,New York, New York 10027; Department of Chemistry, University of Pittsburgh, Parkman Avenue and University Drive,Pittsburgh, Pennsylvania 15260; Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000; Department of Physics andAstronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019; Department of Chemistry,516 Rowland Hall, University of California, Irvine, Irvine, California 92697-2025; Stanford Synchrotron Radiation Laboratory, Stanford LinearAccelerator Center, 2575 Sand Hill Road, Mail Stop 69, Menlo Park, California 94025; School of Chemistry and Biochemistry, Georgia Institute ofTechnology, 770 State Street, Atlanta, Georgia 30332-0400; Geology Department, University of California, Davis, One Shields Avenue,Davis, California 95616-8605; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue,Cambridge, Massachusetts 02139-4307; Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084Received July 23, 2004

http://casey.brown.edu/chemistry/research/LSWang/publications/194.pdf

Role of water in electron-initiated processes and radical chemistry: issues and scientific advances.

We consider on the light of Information Statistical Thermodynamics the basic principles of phenomenological thermodynamic theories, namely, the principles of equipresence, objectivity, and memory, as well as, the characteristics of entropy production. Informational Statistical Thermodynamics arises as a particular application of maximum-information-entropy inference. We discuss how in this perspective, together with the property of contraction of description based on Bogoliubov's hierarchy of relaxation times, it is possible to account for the above-mentioned principles. Particular analyses are carried out on the basis of a model system. Moreover, selecting the basic set of thermodynamical variables in a closed and in truncated approaches, we assess the validity of the approximations. In particular, we derive the limiting conditions under which one recovers the constitutive equations of Linear Irreversible Thermodynamics. The associated equations of evolution for the basic macrovariables and a particular H -theorem are described and discussed.

The basic principles of irreversible thermodynamics in the context of an informational-statistical approach

We analyze the hydrodynamic modes associated with carriers in a photoinjected plasma in a direct-gap polar semiconductor. In this paper we concentrate our attention on the carrier material motion. Resorting to a mechanostatistical approach to irreversible thermodynamics, the coupled equations of evolution for the charge density of electrons and holes are derived. They have the form of hyperbolic equations which imply collective damped wave propagation. The kinetic coefficients on which they depend are determined at this mechanostatistical microscopic level. The corresponding hydrodynamic modes are characterized: they consist of, besides the single quasiparticle (electrons and holes) excitations, two collective modes, namely, the acoustical and optical plasma waves. Their dispersion relations and lifetimes are obtained. These hydrodynamic modes are evidenced and further characterized through the calculation and analysis of the spectrum of Raman scattering of radiation by the carriers. The motion of the charge density is analyzed and we show how the damped wave regime goes over to the Fick-like diffusive regime in the limit of very large wavelengths and very low frequencies.

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Damped plasma waves in photoexcited plasma in semiconductors

A statistical-thermodynamic theory of the phenomenon of stimulated amplification of the population of excitons which lie at the bottom of their lowest-energy band is presented. The experimentally detected "packet" of excitons flowing ballistically is shown to consist of a Schrodinger-Davydov solitary wave, dressed with a cloud of incoherent excitons. Moreover, a secondary excitation by a c.w. laser beam promotes a Frohlich-Bose-Einstein–like condensation, which is responsible for the relevant phenomenon that the lifetime of the soliton is largely increased with increasing pumping power.

https://iopscience.iop.org/article/10.1209/epl/i2000-00198-7/pdf

"Excitoner": Stimulated amplification and propagation of excitons' beams

We describe some aspects of complex behaviour that can be present in biopolymers. The study is based on a nonlinear thermodynamics of non-equilibrium, dissipative systems. Such complexity consists of a Frohlich- Bose- Einstein-like condensation and propagation of Schrodinger- Davydov soliton-wave-like excitations, which are of relevance in Bioenergetics. The question of the soliton lifetime under physiological conditions is discussed, and comparison made with experiments performed in the case of an organic molecular polymer. Further complex behaviour apparently present in ultrasonic medical imaging, dubbed the Frohlich- Cherenkov effect, is briefly discussed.

Complexity in biological systems

This paper and the following one are part of a planned sequence of contributions on the question of the mechano-statistical foundations of irreversible thermodynamics and generalized hydrodynamics, based on the nonequilibrium statistical operator method via the information entropy ensemble. With this we introduce what can be termed Informational Statistical Thermodynamics. The series of papers amounts to an extension and detailed application of a general formalism initiated in papers I and II (quoted in references [12] and [13]) to study the time evolution of the variables selected to describe the nonequilibrium macroscopic states of an N-body system. These variables are to be chosen according to some criteria which the observer uses to define such states, but are otherwise arbitrary. We consider here the set that includes the ordinary fluxes of Linear Irreversible Thermodynamics (LIT), thus raising these variables to the status of state variables, to recover the results comprising the basis of what is now known as Extended Irreversible Thermodynamics (EIT). The time evolution equations for the fluxes are shown to be of the type of generalized Mori-Langevin equations that are nonlinear and nonlocal in space and in time. Under appropriate approximations such equations are reduced to those of the so-called Maxwell-Cattaneo-Vernotte type contained in EIT, which are generalizations of the usual constitutive equations of LIT. In fact, taking a linear approximation in the fluxes and a local-in-time-approach, and considering a quasi-steady state, the equations represent nonlocal-in-space generalized constitutive-like equations for the fluxes.

Áurea R. Vasconcellos

Papers

The basic principles of irreversible thermodynamics in the context of an informational-statistical approach

Damped plasma waves in photoexcited plasma in semiconductors

"Excitoner": Stimulated amplification and propagation of excitons' beams

Complexity in biological systems

Microscopic Approach to Irreversible Thermodynamics III: Generalized Constitutive Equations