NGC 2419 does not challenge MOND, Part 2

I argue that, despite repeated claims of Ibata et al., the globular cluster NGC 2419 does not pose a problem for modified Newtonian dynamics (MOND). I present a new polytropic model with a running polytropic index. This model provides an improved representation of the radial distribution of surface brightness while maintaining a reasonable fit to the velocity dispersion profile. Although it may be argued that the differences with these observations remain large compared to the reported random errors, there are several undetectable systematic effects which render a formal likelihood analysis irrelevant. I comment generally upon these effects and upon the intrinsic limitations of pressure supported objects as tests of gravity.Comment: 3 page, 2 figure

The prediction of rotation curves in gas-dominated dwarf galaxies with modified dynamics

I consider the observed rotation curves of 12 gas-dominated low-surface-brightness galaxies -- objects in which the mass of gas ranges between 2.2 and 27 times the mass of the stellar disk (mean=9.4). This means that, in the usual decomposition of rotation curves into those resulting from various mass components, the mass-to-light ratio of the luminous stellar disk effectively vanishes as an additional adjustable parameter. It is seen that the observed rotation curves reflect the observed structure in gas surface density distribution often in detail. This fact is difficult to comprehend in the context of the dark matter paradigm where the dark halo completely dominates the gravitational potential in the low surface density systems; however it is expected result in the context of modified Newtonian dynamics (MOND) in which the baryonic matter is the only component. With MOND the calculated rotation curves are effectively parameter-free predictions.Comment: 9 pages, 4 figures, submitte

A historical perspective on Modified Newtonian Dynamics

I review the history and development of Modified Newtonian Dynamics (MOND) beginning with the phenomenological basis as it existed in the early 1980s. I consider Milgrom's papers of 1983 introducing the idea and its consequences for galaxies and galaxy groups, as well as the initial reactions, both negative and positive. The early criticisms were primarily on matters of principle, such as the absence of conservation laws and perceived cosmological problems; an important step in addressing these issues was the development of the Lagrangian-based non-relativistic theory of Bekenstein and Milgrom. This theory led to the development of a tentative relativistic theory that formed the basis for later multi-field theories of gravity. On an empirical level the predictive success of the idea with respect to the phenomenology of galaxies presents considerable challenges for cold dark matter. For MOND the essential challenge remains the absence of a generally accepted theoretical underpinning of the idea and, thus, cosmological predictions. I briefly review recent progress in this direction. Finally I discuss the role and sociology of unconventional ideas in astronomy in the presence of a strongly entrenched standard paradigm.Comment: 25 pages, 9 figures, previous uploaded file was out of date, Canadian Journal of Physic

The Youth Transitions Study: Final Report

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Bounding quantum gate error rate based on reported average fidelity

Remarkable experimental advances in quantum computing are exemplified by recent announcements of impressive average gate fidelities exceeding 99.9% for single-qubit gates and 99% for two-qubit gates. Although these high numbers engender optimism that fault-tolerant quantum computing is within reach, the connection of average gate fidelity with fault-tolerance requirements is not direct. Here we use reported average gate fidelity to determine an upper bound on the quantum-gate error rate, which is the appropriate metric for assessing progress towards fault-tolerant quantum computation, and we demonstrate that this bound is asymptotically tight for general noise. Although this bound is unlikely to be saturated by experimental noise, we demonstrate using explicit examples that the bound indicates a realistic deviation between the true error rate and the reported average fidelity. We introduce the Pauli distance as a measure of this deviation, and we show that knowledge of the Pauli distance enables tighter estimates of the error rate of quantum gates.Comment: New Journal of Physics Fast Track Communication. Gold open access journa

A tensor-vector-scalar framework for modified dynamics and cosmic dark matter

I describe a tensor-vector-scalar theory that reconciles the galaxy scale success of modified Newtonian dynamics (MOND) with the cosmological scale evidence for CDM. The theory provides a cosmological basis for MOND in the sense that the predicted phenomenology only arises in a cosmological background. The theory contains an evolving effective potential, and scalar field oscillations in this potential comprise the cold dark matter; the de Broglie wavelength of these soft bosons, however, is sufficiently large that they cannot accumulate in galaxies. The theory predicts, inevitably, a constant anomalous acceleration in the outer solar system which, depending upon the choice of parameters, can be consistent with that detected by the Pioneer spacecrafts.Comment: minor corrections, numerical error corrected in eq. 37 and subsequent equations, accepted MNRA

THE INFORMATION CONTENT OF IMPLIED VOLATILITY FROM OPTIONS ON AGRICULTURAL FUTURES CONTRACTS

Agricultural risk managers need forecasts of price volatility that are accurate and meaningful. This is especially true given the greater emphasis on firm level risk measurement and management (e.g., Value-at-Risk and Enterprise Risk Management). Implied volatility is known to provide a readily available, market based forecast of volatility. Because of this, it is often considered to be the "best" available (e.g., optimal) volatility forecast. However, many studies have provided evidence contrary to this claim for many markets (Figlewski). This research examines the forecasting performance of implied volatility derived from the Black-1976 option pricing model in predicting 1-week volatility of nearby live cattle futures prices. Unlike many studies of implied volatility, this research takes a practical approach to evaluating implied volatility, namely from the perspective of an agribusiness risk manager who uses implied volatility in risk management applications, and thus needs to understand its forecasting performance. This research also uses a methodology that avoids overlapping forecast horizons. As well, the methodology focuses on forecast errors that can reduce interpretive issues that can arise from traditional forecast evaluation procedures. Results suggest that implied volatility derived from nearby options contracts on live cattle futures is a biased and inefficient forecast of 1-week nearby futures price volatility, but encompasses all information provided by a time series forecast (i.e., GARCH). As well, our results suggest that implied volatility has improved as a forecast of 1-week volatility over time. These results provide practical information to risk managers on the bias, efficiency, and information content of implied volatility from live cattle options markets, and provide practical suggestions on how to adjust the bias and inefficiency that is found in this forecasting framework.Marketing,

Multiple Horizons and Information in USDA Production Forecasts

USDA livestock production forecasts are evaluated for information across multiple horizons using the direct test developed by Vuchelen and Gutierrez. Forecasts are explicitly tested for rationality (unbiased and efficient) as well as for incremental information out to three quarters ahead. The results suggest that although the forecasts are often not rational, they typically do provide the forecast user with unique information at each horizon. Turkey and milk production forecasts tended to provide the most consistent performance, while beef production forecasts provided little information beyond the two quarter horizon.Livestock Production/Industries,

Is the Local Basis Really Local?

Conventional wisdom suggests the local cash - futures basis is determined from local supply and demand conditions. However, it may be the case that local elevators look to other locations, such as terminal locations, and adjust for transportation differentials when determining the basis for their particular market. If so, certain grain marketing locations (e.g., export and interior terminal locations) may play an important role in discovering and ultimately determining the basis for other local markets. This hypothesis is examined for the #2 yellow corn basis at various export terminal (Gulf; Toledo), river terminal (Illinois River; Omaha) and interior (S. Central Illinois; N. Central Iowa; Denver) locations. Specifically, if the basis calculated at one market location is found to lead the basis at another market location, then this suggests that the leading market plays a role in determining the basis for the other market. The findings suggest that corn basis calculated at the export terminal markets of Toledo and the U.S. Gulf, as well as the Illinois River, may indeed provide valuable information in determining the basis for other river terminal and interior locations.Marketing,

Comparing Hedging Effectiveness: An Application of the Encompassing Principle

An empirical methodology is developed for statistically testing the hedging effectiveness among competing futures contracts. The presented methodology is based on the encompassing principle, widely used in the forecasting literature, and applied here to minimum variance hedging regressions. Intuitively, the test is based on an alternative futures contract's ability to reduce residual basis risk by offering either diversification or a smaller absolute level of basis risk than a preferred futures contract. The methodology is easily extended to cases involving multiple hedging instruments and general hedge ratio models. Empirical applications suggest that the encompassing methodology can provide information beyond traditional approaches of comparing hedging effectiveness.cross-hedging, encompassing, hedging effectiveness, Research Methods/ Statistical Methods,