Gel Estimation and Inference with Non-Smooth Moment Indicators and Dynamic Data

In this paper we demonstrate consistency and asymptotic normality for Generalized Empirical Likelihood (GEL) estimation in dynamic models when the moment indicators being used are the non-differentiable functions of the parameters of interest.

On the Consistency of Approximate Maximizing Estimator Sequences in the Case of Quasiconcave Functions

This paper demonstrates consistency for estimators obtained by approximately maximizing a sequence of stochastic quasiconcave functions on RP that converges in probability pointwise to a non-stochastic function. In the scalar parameter case all that is necessary for consistency is that the parameter value of interest is a unique maximizer of the limiting function. However, in the vector parameter case certain further conditions on the limiting function are necessary to establish consistency. The paper also discusses the relation of these results to existing results on the consistency of estimators obtained by approximately maximizing concave functions and to the concepts of hypoconvergence and epiconvergence.

Regression towards the mode

We propose a semi-parametric mode regression estimator for the case in which the variate of interest is continuous and observable over its entire un- bounded support. The estimator is semi-parametric in that the conditional mode is specified as a parametric function, but only mild assumptions are made about the nature of the conditional density of interest. We show that the proposed estimator is consistent and has a tractable asymptotic distribution. Simulation results and an empirical illustration are provided to highlight the practicality and usefulness of the estimator.

An Interpretation of the Enhancement of the Water Dipole Moment Due to the Presence of Other Water Molecules

The dipole moment of the gas phase water monomer is 1.85 D. When solvated in bulk water, the dipole moment of an individual water molecule is observed to be enhanced to the much larger value of 2.9 ± 0.6 D. To understand the origin of this dipole moment enhancement, the effective fragment potential (EFP) method is used to solvate an ab initio water molecule to predict the dipole moments for various cluster sizes. The dipole moment as a function of cluster size, nH2O, is investigated [for n = 6–20 (even n), 26, 32, 41, and 50]. Localized charge distributions are used in conjunction with localized molecular orbitals to interpret the dipole moment enhancement. These calculations suggest that the enhancement of the dipole moment originates from the decrease of the angle between the dipole vectors of the lone pairs on oxygen as the number of hydrogen bonds to that oxygen increases. Thus, the decreased angle, and the consequent increase in water dipole moment, is most likely to occur in environments with a larger number of hydrogen bonds, such as the center of a cluster of water molecules

Theoretical Study of the Solvation of Fluorine and Chlorine Anions by Water

The solvation of fluoride and chloride anions (F- and Cl-, respectively) by water has been studied using effective fragment potentials (EFPs) for the water molecules and ab initio quantum mechanics for the anions. In particular, the number of water molecules required to fully surround each anion has been investigated. Monte Carlo calculations have been used in an attempt to find the solvated system X-(H2O)n (X = F, Cl) with the lowest energy for each value of n. It is predicted that 18 water molecules are required to form a complete solvation shell around a Cl- anion, where “complete solvation” is interpreted as an ion that is completely surrounded by solvent molecules. Although fewer water molecules may fully solvate the Cl-anion, such structures are higher in energy than partially solvated molecules, up to n ≥ 18. Calculations on the F- anion suggest that 15 water molecules are required for a complete solvation shell. The EFP predictions are in good agreement with the relative energies predicted by ab initio energy calculations at the EFP geometries

Semi-Parametric Estimation of a Logit Model

In this paper, I develop an estimator for a semi-parametric logit model based on a kernel-weighted average of pairwise conditional logit terms. Then I demonstrate consistency, asymptotic normality, and consistent asymptotic covariance matrix estimation for this estimator using results for sequences of $U$-statistic.

Uniform Convergence in Extended Probability of Sub-Gradients of Convex Functions

It is well known that if a sequence of stochastic convex functions on $\mathbb{R}^{d}$ converges in probability point-wise to some non-stochastic function then the limit function is convex and the convergence is uniform on compact sets; see Andersen and Gill (1982) and Pollard (1991). In the present paper, I establish that if the limiting function is differentiable then any sequence of measurable sub-gradients of the stochastic convex functions converges in extended probability to the gradient of the limit function uniformly on compact sets

Aspects of the nutritional physiology of the perlemoen Haliotis midae (L.) and red abalone H. rufescens (Swainson)

The source of abalone for human consumption has shown a dramatic shift away from wild-capture fisheries in the last 30 years, with over 90% of global production now coming from aquaculture. Farmers initially relied on the natural food of abalone (macroalgae) as a culture feed, though in regions where macroalgae availability was limiting, the need to develop formulated feeds was evident. Extensive research effort has led to the development of a number of formulated feed products currently employed in the industry. These feeds, however, differ markedly from the mixed macroalgal diets that abalone have evolved to utilise, particularly in terms of protein content and carbohydrate structure. The degree to which the nutritional physiology of abalone responds to these novel formulated diets, with and without macroalgal supplementation, was investigated in the current study. A multifaceted approach, combining growth trials, stable isotope nutrient tracers and metabolic experiments, was employed to gain insight into the post-absorption dynamics and utilisation of dietary nutrients under varying dietary regimes of fresh macroalgae and formulated feed. Growth trials conducted with both Haliotis rufescens and H. midae showed significantly higher growth and protein utilisation efficiency for abalone fed macroalgal diets compared to formulated feeds. Furthermore, when formulated feeds were supplemented with macroalgae to form combination diets, growth and the utilization of protein was improved compared to the formulated-feed-only diet. The poor utilisation of protein by H. midae fed the formulated feed could be traced, using a method combining stable isotope bio-markers with a Bayesian mixing model (SIAR), to the low incorporation of the fishmeal component of protein in the diet. The marked postprandial drop in the O:N ratio on abalone fed formulated feeds indicate that the protein was being diverted into catabolic metabolic pathways. The metabolic cost of digestion, termed specific dynamic action (SDA), was negated as a factor in the improved growth of abalone fed macroalgal diets, with the SDA coefficient 2.1 times that observed for formulated feed. Furthermore, the postprandial haemolymph glucose concentration (HGC) in H. midae was elevated when fed formulated feed compared to macroalgae. The high levels of circulating glucose are likely a result of the structure the carbohydrate source in formulated feeds and stimulate the deposition of glycogen through the allosteric control of glycogen synthase. Formulated feeds produced higher cooked meat yields in canning simulation trials, suggesting that muscle glycogen content may indirectly play a role in increasing canning yields through the displacement of collagen. The results of these empirical studies are synthesised under key themes, discussed within the context of their potential commercial relevance and future research directions are highlighted

Electric Propulsion Upper-Stage for Launch Vehicle Capability Enhancement

The NASA In-Space Propulsion Technology Project Office initiated a preliminary study to evaluate the performance benefits of a solar electric propulsion (SEP) upper-stage with existing and near-term small launch vehicles. The analysis included circular and elliptical Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO) transfers, and LEO to Low Lunar Orbit (LLO) applications. SEP subsystem options included state-of-the-art and near-term solar arrays and electric thrusters. In-depth evaluations of the Aerojet BPT-4000 Hall thruster and NEXT gridded ion engine were conducted to compare performance, cost and revenue potential. Preliminary results indicate that Hall thruster technology is favored for low-cost, low power SEP stages, while gridded-ion engines are favored for higher power SEP systems unfettered by transfer time constraints. A low-cost point design is presented that details one possible stage configuration and outlines system limitations, in particular fairing volume constraints. The results demonstrate mission enhancements to large and medium class launch vehicles, and mission enabling performance when SEP system upper stages are mounted to low-cost launchers such as the Minotaur and Falcon 1. Study results indicate the potential use of SEP upper stages to double GEO payload mass capability and to possibly enable launch on demand capability for GEO assets. Transition from government to commercial applications, with associated cost/benefit analysis, has also been assessed. The sensitivity of system performance to specific impulse, array power, thruster size, and component costs are also discussed