Pursuing the planet-debris disk connection: Analysis of upper limits from the Anglo-Australian Planet Search

Solid material in protoplanetary discs will suffer one of two fates after the epoch of planet formation; either being bound up into planetary bodies, or remaining in smaller planetesimals to be ground into dust. These end states are identified through detection of sub-stellar companions by periodic radial velocity (or transit) variations of the star, and excess emission at mid- and far-infrared wavelengths, respectively. Since the material that goes into producing the observable outcomes of planet formation is the same, we might expect these components to be related both to each other and their host star. Heretofore, our knowledge of planetary systems around other stars has been strongly limited by instrumental sensitivity. In this work, we combine observations at far-infrared wavelengths by IRAS, Spitzer, and Herschel with limits on planetary companions derived from non-detections in the 16-year Anglo-Australian Planet Search to clarify the architectures of these (potential) planetary systems and search for evidence of correlations between their constituent parts. We find no convincing evidence of such correlations, possibly owing to the dynamical history of the disk systems, or the greater distance of the planet-search targets. Our results place robust limits on the presence of Jupiter analogs which, in concert with the debris disk observations, provides insights on the small-body dynamics of these nearby systems.Comment: Accepted for publication in A

"Peso Problem" Explanations for Term Structure Anomalies

We examine the empirical evidence on the expectations hypothesis of the term structure of interest rates in the United States, the United Kingdom, and Germany using the Campbell-Shiller (1991) regressions and a vector-autoregressive" methodology. We argue that anomalies in the U.S. term structure, documented by Campbell and Shiller (1991), may be due to a generalized peso problem in which a high-interest rate regime occurred less frequently in the sample of U.S. data than was rationally anticipated. We formalize this idea as a regime-switching model of short-term interest rates estimated with data" from seven countries. Technically, this model extends recent research on regime-switching models with state-dependent transitions to a cross-sectional setting. Use of the small sample distributions generated by the regime-switching model for inference considerably weakens the evidence against the expectations hypothesis, but it remains somewhat implausible that our data-generating process produced the U.S. data. However, a model that combines moderate time-variation in term premiums with peso-problem effects is largely consistent with term structure data from the U.S., U.K., and Germany.

The Implications of First-Order Risk Aversion for Asset Market Risk Premiums

Existing general equilibrium models based on traditional expected utility preferences have been unable to explain the excess return predictability observed in equity markets, bond markets, and foreign exchange markets. In this paper, we abandon the expected-utility hypothesis in favor of preferences that exhibit first-order risk aversion. We incorporate these preferences into a general equilibrium two-country monetary model, solve the model numerically, and compare the quantitative implications of the model to estimates obtained from U.S. and Japanese data for equity, bond and foreign exchange markets. Although increasing the degree of first-order risk aversion substantially increases excess return predictability, the model remains incapable of generating excess return predictability sufficiently large to match the data. We conclude that the observed patterns of excess return predictability are unlikely to be explained purely by time-varying risk premiums generated by highly risk averse agents in a complete markets economy.

"Peso problem" explanations for term structure anomalies

We examine the empirical evidence on the expectation hypothesis of the term structure of interest rates in the United States, the United Kingdom, and Germany using the Campbell-Shiller (1991) regressions and a vector-autoregressive methodology. We argue that anomalies in the U.S. term structure, documented by Campbell and Shiller (1991), may be due to a generalized peso problem in which a high-interest rate regime occurred less frequently in the sample of U.S. data than was rationally anticipated. We formalize this idea as a regime-switching model of short-term interest rates estimated with data from seven countries. Technically, this model extends recent research on regime-switching models with state-dependent transitions to a cross-sectional setting. Use of the small sample distributions generated by regime-switching model for inference considerably weakens the evidence against the expectations hypothesis, but it remains somewhat implausible that our data-generating process produced the U.S. data. However, a model that combines moderate time-variation in term premiums with peso-problem effects is largely consistent with term-structure data from the U.S., U.K., and Germany.Interest rates ; Econometric models

Motivational Factors And The Hospitality Industry: A Case Study Examining The Effects Of Changes In The Working Environment

The Mandarin Oriental Hotel in Bangkok is a world-wide leader in hospitality management. A critical ingredient for their success has been developing and maintaining superior performance from their employees. How is that accomplished? What Human Resource Management (HRM) practices should organizations invest in to acquire and retain great employees? Recent studies have demonstrated the importance of providing a supportive work environment, one that engenders employee satisfaction and promotes effective service performance among hospitality employees. But what is a supportive environment for hotel workers who are required to be responsive to the needs of guests twenty four hours a day? The Mandarin Oriental’s unique approach involved building a separate area in the hotel dedicated to the well-being of their employees. This area—The O-Zone—originated from the idea of providing workplaces which support fun and enjoyment as part of work-life balance. The case focuses attention on how changes in the working environment can significantly enhance the recognition and appreciation of employees A dedicated employee center in the hospitality industry has not been explored before and offers up an exceptional opportunity to examine the effect on motivation and how the center may be appreciated differently by employees based on gender, department and work experience—an important consideration for Human Resources when designing incentive programs

Progress Towards a NASA Earth Science Reuse Enablement System (RES)

A Reuse Enablement System (RES) allows developers of Earth science software to contribute software for reuse by others and.for users to find, select, and obtain software for reuse in their own systems. This paper describes work that the X4S,4 Earth Science Data Systems (ESDS) Software Reuse Working Group has completed to date in the development of an RES for NASA

Software Reuse Methods to Improve Technological Infrastructure for e-Science

Social computing has the potential to contribute to scientific research. Ongoing developments in information and communications technology improve capabilities for enabling scientific research, including research fostered by social computing capabilities. The recent emergence of e-Science practices has demonstrated the benefits from improvements in the technological infrastructure, or cyber-infrastructure, that has been developed to support science. Cloud computing is one example of this e-Science trend. Our own work in the area of software reuse offers methods that can be used to improve new technological development, including cloud computing capabilities, to support scientific research practices. In this paper, we focus on software reuse and its potential to contribute to the development and evaluation of information systems and related services designed to support new capabilities for conducting scientific research

A Generalized Method for Calculating Atmospheric Ionization by Energetic Electron Precipitation

Accurate specification of ionization production by energetic electron precipitation is critical for atmospheric chemistry models to assess the resultant atmospheric effects. Recent model-observation comparison studies have increasingly highlighted the importance of considering precipitation fluxes in the full range of electron energy and pitch angle. However, previous parameterization methods were mostly proposed for isotropically precipitation electrons with energies up to 1 MeV, and the pitch angle dependence has not yet been parameterized. In this paper, we first characterize and tabulate the atmospheric ionization response to monoenergetic electrons with different pitch angles and energies between ∼3 keV and ∼33 MeV. A generalized method that fully accounts for the dependence of ionization production on background atmospheric conditions, electron energy, and pitch angle has been developed based on the parameterization method of Fang et al. (2010, https://doi.org/10.1029/2010GL045406). Moreover, we validate this method using 100 random atmospheric profiles and precipitation fluxes with monoenergetic and exponential energy distributions, and isotropic and sine pitch angle distributions. In a suite of 6,100 validation tests, the error in peak ionization altitude is found to be within 1 km in 91% of all the tests with a mean error of 2.7% in peak ionization rate and 1.9% in total ionization. This method therefore provides a reliable means to convert space-measured precipitation energy and pitch angle distributions into ionization inputs for atmospheric chemistry models.publishedVersio