Heterogeneity and the nonparametric analysis of consumer choice: conditions for invertibility

This paper considers structural nonparametric random utility models for continuous choice variables. It provides sufficient conditions on random preferences to yield reduced- form systems of nonparametric stochastic demand functions that allow global invertibility between demands and random utility components. Invertibility is essential for global identifcation of structural consumer demand models, for the existence of well-specified probability models of choice and for the nonparametric analysis of revealed stochastic preference

The Instability of Preferences: Uncertain Futures and the Incommensurable and Intersubjective Nature of Value(s)

The default assumption of standard economics is to treat preferences as exogenously ‘given’, consistent with one another, ‘revealed’ by past choices, and context independent. There has been increased interest recently (within behavioural economics) in the impact of inconsistent or irrational preferences and (more broadly) in dynamic and endogenous preferences. This paper builds on these challenges to standard assumptions by analysing the pivotal role of three aspects of preference formation in explaining capitalist dynamics and market instability. These are the constant creation of new preferences and the indeterminacy of choice sets in the context of widespread product innovation; the moral indeterminacy implied by conflicting and incommensurable social norms attaching to market goods where there is no single scale of value and hence no unique set of rational trade-offs; and, lastly, the contingent social and market construction of the product differentiation, quality attribution, and value assessments central to preference formation. The paper concludes by considering implications for economics as a discipline.Eine Standardannahme in den Wirtschaftswissenschaften ist, dass Präferenzen exogen „gegeben“, konsistent, durch vorausgegangene Entscheidungen offenbart und kontextunabhängig sind. In Kreisen der Verhaltensökonomie ist neuerlich ein gestiegenes Interesse an den Auswirkungen widersprüchlicher oder irrationaler Präferenzen und – etwas weiter gefasst – an dynamischen und endogenen Präferenzen zu verzeichnen. Das vorliegende Papier geht von diesen Kritiken aus und untersucht die zentrale Rolle dreier Aspekte der Präferenzbildung zur Erklärung von kapitalistischer Dynamik und Marktinstabilität: 1) die konstante Schaffung neuer Präferenzen und die Unbestimmtheit von Auswahlkriterien angesichts einer großen Anzahl von Produktinnovationen; 2) die moralische Unbestimmtheit aufgrund sich entgegenstehender und nicht vergleichbarer sozialer Normen, die mit Marktgütern in Zusammenhang gebracht werden, ohne das Vorhandensein einer allgemeingültigen Werteskala und somit ohne eine feste Auswahl an möglichen rationalen Ausgleichen; und 3) die ungewisse soziale und marktbezogene Zusammensetzung von Produktdifferenzierung, Qualitätszuschreibung und Wertbeimessung, die für die Präferenzbildung von zentraler Bedeutung sind. Das Papier schließt mit Überlegungen, welche Implikationen sich daraus für die Disziplin der Wirtschaftswissenschaften ergeben könnten.Contents 1 Introduction 2 The different facets of preferences 3 Preferences in economics and reasons for a new approach 4 Innovation, preference formation, and uncertain futures 5 Incommensurable values and preference instability 6 The market construction of value and preferences 7 Conclusion and potential implications for the discipline of economics Reference

Characterization of solar cells for space applications. Volume 11: Electrical characteristics of 2 ohm-cm, 228 micron wraparound solar cells as a function of intensity, temperature, and irradiation

Parametric characterization data on Spectrolab 2 by 4 cm, 2 ohm/cm, 228 micron thick wraparound cell, a candidate for the Solar Electric Propulsion Mission, are presented. These data consist of the electrical characteristics of the solar cell under a wide range of temperature and illumination intensity combinations of the type encountered in space applications

Characterization of solar cells for space applications. Volume 8: Electrical characteristics of Spectrolab BSF, BSR, textured 290-micron solar cells (K7) as a function of intensity, temperature and irradiation

A set of parametric data is presented on the Spectrolab textured, back-surface-field, back-surface-reflector solar cell which is a commercially available product

Characterization of solar cells for space applications. Volume 12: Electrical characteristics of Solarex BSF, 2-ohm-cm, 50-micron solar cells (1978 pilot line) as a function of intensity, temperature, and irradiation

Electrical characteristics of Solarex back-surface-field, 2-ohm-cm, 50-micron N/P silicon solar cells are presented in graphical and tabular format as a function of solar illumination intensity, temperature, and irradiation

Sgr A* Polarization: No ADAF, Low Accretion Rate, and Non-Thermal Synchrotron Emission

The recent detection of polarized radiation from Sgr A* requires a non-thermal electron distribution for the emitting plasma. The Faraday rotation measure must be small, placing strong limits on the density and magnetic field strength. We show that these constraints rule out advection-dominated accretion flow models. We construct a simple two-component model which can reproduce both the radio to mm spectrum and the polarization. This model predicts that the polarization should rise to nearly 100% at shorter wavelengths. The first component, possibly a black-hole powered jet, is compact, low density, and self-absorbed near 1 mm with ordered magnetic field, relativistic Alfven speed, and a non-thermal electron distribution. The second component is poorly constrained, but may be a convection-dominated accretion flow with dM/dt~10^-9 M_Sun/yr, in which feedback from accretion onto the black hole suppresses the accretion rate at large radii. The black hole shadow should be detectable with sub-mm VLBI.Comment: 4 pages, 1 figure, accepted by ApJL, several changes from submitted versio

Characterization of solar cells for space applications. Volume 13: Electrical characteristics of Hughes LPE gallium arsenide solar cells as a function of intensity and temperature

Electrical characteristics of Hughes Liquid phase epitaxy, P/N gallium aluminum arsenide solar cells are presented in graphical and tabular format as a function of solar illumination intensity and temperature

The Role of Magnetic Field Dissipation in the Black Hole Candidate Sgr A*

The compact, nonthermal radio source Sgr A* at the Galactic Center appears to be coincident with a 2.6 million solar mass point-like object. Its energy source may be the release of gravitational energy as gas from the interstellar medium descends into its potential well. Simple attempts at calculating the spectrum and flux based on this picture have come close to the observations, yet have had difficulty in accounting for the low efficiency in this source. There now appear to be two reasons for this low conversion rate: (1) the plasma separates into two temperatures, with the protons attaining a significantly higher temperature than that of the radiating electrons, and (2) the magnetic field, B, is sub-equipartition, which reduces the magnetic bremsstrahlung emissivity, and therefore the overall power of Sgr A*. We investigate the latter with improvement over what has been attempted before: rather than calculating B based on a presumed model, we instead infer its distribution with radius empirically with the requirement that the resulting spectrum matches the observations. Our ansatz for B(r) is motivated in part by earlier calculations of the expected magnetic dissipation rate due to reconnection in a compressed flow. We find reasonable agreement with the observed spectrum of Sgr A* as long as its distribution consists of 3 primary components: an outer equipartition field, a roughly constant field at intermediate radii (~1000 Schwarzschild radii), and an inner dynamo (more or less within the last stable orbit for a non-rotating black hole) which increases B to about 100 Gauss. The latter component accounts for the observed sub-millimiter hump in this source.Comment: 33 pages including 2 figures; submitted to Ap

What is the Accretion Rate in Sgr A*?

The radio source Sgr A* at the center of our Galaxy is believed to be a 2.6 x 10^6 solar mass black hole which accretes gas from the winds of nearby stars. We show that limits on the X-ray and infrared emission from the Galactic Center provide an upper limit of ~ 8 x 10^{-5} solar masses per year on the mass accretion rate in Sgr A*. The advection-dominated accretion flow (ADAF) model favors a rate < 10^{-5} solar masses per year. In comparison, the Bondi accretion rate onto Sgr A*, estimated using the observed spatial distribution of mass losing stars and assuming non-interacting stellar winds, is ~ 3 x 10^{-5} solar masses per year. There is thus rough agreement between the Bondi, the ADAF, and the X-ray inferred accretion rates for Sgr A*. We discuss uncertainties in these estimates, emphasizing the importance of upcoming observations by the Chandra X-ray observatory (CXO) for tightening the X-ray derived limits.Comment: to appear in ApJ Letter

VLTI/VINCI observations of the nucleus of NGC 1068 using the adaptive optics system MACAO

We present the first near-infrared K-band long-baseline interferometric measurement of the prototype Seyfert 2 galaxy NGC 1068 with resolution lambda/B \~ 10 mas obtained with the Very Large Telescope Interferometer (VLTI) and the two 8.2m Unit Telescopes UT2 and UT3. The adaptive optics system MACAO was employed to deliver wavefront-corrected beams to the K-band commissioning instrument VINCI. A squared visibility amplitude of 16.3 +/- 4.3 % was measured for NGC 1068 at a sky-projected baseline length of 45.8 m and azimuth angle 44.9 deg. This value corresponds to a FWHM of the K-band intensity distribution of 5.0 +/- 0.5 mas (0.4 +/- 0.04 pc) at the distance of NGC 1068) if it consists of a single Gaussian component. Taking into account K-band speckle interferometry observations (Wittkowski et al. 1998; Weinberger et al. 1999; Weigelt et al. 2004), we favor a multi-component model for the intensity distribution where a part of the flux originates from scales clearly smaller than about 5 mas (<0.4 pc), and another part of the flux from larger scales. The K-band emission from the small (< 5 mas) scales might arise from substructure of the dusty nuclear torus, or directly from the central accretion flow viewed through only moderate extinction.Comment: Accepted for publication in Astronomy and Astrophysics Letter