Thermal balance of the atmospheres of Jupiter and Uranus

Two-dimensional, radiative-convective-dynamical models of the visible atmospheres of Jupiter and Uranus are presented. Zonally-averaged temperatures and heat fluxes are calculated numerically as functions of pressure and latitude. In addition to radiative heat fluxes, the dynamical heat flux due to large-scale baroclinic eddies is included and is parametrized using a mixing length theory which gives heat fluxes similar to those of Stone. The results for Jupiter indicate that the internal heat flow is non-uniform in latitude and nearly balances the net radiative flux leaving the atmosphere. The thermal emission is found to be uniform in latitude in agreement with Pioneer and Voyager observations. Baroclinic eddies are calculated to transport only a small amount of the meridional heat flow necessary to account for the uniformity of thermal emission with latitude. The bulk of the meridional heat transfer is found to occur very deep in the stable interior of Jupiter as originally proposed by Ingersoll and Porco. The relative importance of baroclinic eddies vs. internal heat flow in the thermal balance of Uranus depends on the ratio of emitted thermal power to absorbed solar power. The thermal balance of Uranus is compared to that of Jupiter for different values of this ratio

An information approach to the dynamics in farm income: implications for farmland markets

The valuation of farmland is a perennial issue for agricultural policy, given its importance in the farm investment portfolio. Despite the significance of farmland values to farmer wealth, prediction remains a difficult task. This study develops a dynamic information measure to examine the informational content of farmland values and farm income in explaining the distribution of farmland values over time

Lunar and planetary studies

This grant supports the core program in planetary astronomy at Caltech. The research includes observations in the IR, sub-mm, mm and cm wavelengths at national and Caltech observatories with a strong emphasis on integrating the observations with spacecraft data and with models of atmospheric structure, dynamics and chemistry. Muhleman's group made extensive observations of Saturn, Uranus and Neptune which are being interpreted in terms of deep atmospheric structures which are obvious in the 2 and 6 cm maps of Saturn and Uranus. The microwave measurements are one of the few sources of information below the 2 bar level. Goldreich is investigating the dynamics of narrow rings with postdoctoral fellow, Pierre-Yves Longaretti. Their work has focused on the role of collisional stresses on the precession of the rings, since the Voyager radio science results imply that the previous model based on the ring's self-gravity is not the entire story. In addition Borderies, Goldreich and Tremaine have completed an investigation of the dynamics of the Encke division in Saturn's A ring

Statistical mechanics of scale-free networks at a critical point: Complexity without irreversibility?

Based on a rigorous extension of classical statistical mechanics to networks, we study a specific microscopic network Hamiltonian. The form of this Hamiltonian is derived from the assumption that individual nodes increase/decrease their utility by linking to nodes with a higher/lower degree than their own. We interpret utility as an equivalent to energy in physical systems and discuss the temperature dependence of the emerging networks. We observe the existence of a critical temperature $T_c$ where total energy (utility) and network-architecture undergo radical changes. Along this topological transition we obtain scale-free networks with complex hierarchical topology. In contrast to models for scale-free networks introduced so far, the scale-free nature emerges within equilibrium, with a clearly defined microcanonical ensemble and the principle of detailed balance strictly fulfilled. This provides clear evidence that 'complex' networks may arise without irreversibility. The results presented here should find a wide variety of applications in socio-economic statistical systems.Comment: 4 pages, 5 figure

The Beginning of Digital Wisdom

Marc Prensky, who popularized the term “digital natives” more than ten years ago, now emphasizes the need for “digital wisdom”: using digital technologies wisely to become wiser. Recent research reveals that so-called digital natives are often “digital naïves”—familiarity with digital technologies does not translate into facility with them. Incoming college students report declining confidence in their computer skills and report very modest improvements by the time they graduate. Employers report deficiencies in the technological skills of college graduates and, perhaps most troubling, studies of youth and young adults show that ethical and moral reasoning does not extend much beyond self-protection. The more we learn about our future, current, and recent students, the clearer it is that many are not equipped to use digital technologies wisely to become wiser people. In 2011, the Seattle Pacific University Library established a new service area for students called the Tech Desk. Initially intended as a place where students could get help with and access to new technologies needed for academic work, this program area quickly became an incubator for ideas and innovations around meeting students’ technological needs. Responding to observations and feedback, including important insights gained through a survey conducted in 2014, the authors have been evolving a conceptual and practical approach to digital wisdom to enhance our students’ academic, vocational, and spiritual development. This paper summarizes what we have learned about our students’ needs and interests, the theological framework we are using to respond to these, and the curricular and co-curricular changes we are pursuing

Realization Utility with Reference-Dependent Preferences

We develop a tractable model of realization utility that studies the role of reference-dependent S-shaped preferences in a dynamic investment setting with reinvestment. Our model generates both voluntarily realized gains and losses. It makes specific predictions about the volume of gains and losses, the holding periods, and the sizes of both realized and paper gains and losses that can be calibrated to a variety of statistics, including the Odean measure of the disposition effect. Our model also predicts several anomalies including, among others, the flattening of the capital market line and a negative price for idiosyncratic risk.Comment: appears in The Review of Financial Studies (2013

The Mars observer camera

A camera designed to operate under the extreme constraints of the Mars Observer Mission was selected by NASA in April, 1986. Contingent upon final confirmation in mid-November, the Mars Observer Camera (MOC) will begin acquiring images of the surface and atmosphere of Mars in September-October 1991. The MOC incorporates both a wide angle system for low resolution global monitoring and intermediate resolution regional targeting, and a narrow angle system for high resolution selective surveys. Camera electronics provide control of image clocking and on-board, internal editing and buffering to match whatever spacecraft data system capabilities are allocated to the experiment. The objectives of the MOC experiment follow