Evaluating the methodology of social experiments

Welfare ; Econometric models

Autonomous RPRV Navigation, Guidance and Control

Dryden Flight Research Center has the responsibility for flight testing of advanced remotely piloted research vehicles (RPRV) to explore highly maneuverable aircraft technology, and to test advanced structural concepts, and related aeronautical technologies which can yield important research results with significant cost benefits. The primary purpose is to provide the preliminary design of an upgraded automatic approach and landing control system and flight director display to improve landing performance and reduce pilot workload. A secondary purpose is to determine the feasibility of an onboard autonomous navigation, orbit, and landing capability for safe vehicle recovery in the event of loss of telemetry uplink communication with the vehicles. The current RPRV approach and landing method, the proposed automatic and manual approach and autoland system, and an autonomous navigation, orbit, and landing system concept which is based on existing operational technology are described

Maximum Entropy and Bayesian Data Analysis: Entropic Priors

The problem of assigning probability distributions which objectively reflect the prior information available about experiments is one of the major stumbling blocks in the use of Bayesian methods of data analysis. In this paper the method of Maximum (relative) Entropy (ME) is used to translate the information contained in the known form of the likelihood into a prior distribution for Bayesian inference. The argument is inspired and guided by intuition gained from the successful use of ME methods in statistical mechanics. For experiments that cannot be repeated the resulting "entropic prior" is formally identical with the Einstein fluctuation formula. For repeatable experiments, however, the expected value of the entropy of the likelihood turns out to be relevant information that must be included in the analysis. The important case of a Gaussian likelihood is treated in detail.Comment: 23 pages, 2 figure

Physical Investigation of the Potentially Hazardous Asteroid (144898) 2004 VD17

In this paper we present the observational campaign carried out at ESO NTT and VLT in April and May 2006 to investigate the nature and the structure of the Near Earth Object (144898) 2004 VD17. In spite of a great quantity of dynamical information, according to which it will have a close approach with the Earth in the next century, the physical properties of this asteroid are largely unknown. We performed visible and near--infrared photometry and spectroscopy, as well as polarimetric observations. Polarimetric and spectroscopic data allowed us to classify 2004 VD17 as an E-type asteroid. A good agreement was also found with the spectrum of the aubrite meteorite Mayo Belwa. On the basis of the polarimetric albedo (p_v=0.45) and of photometric data, we estimated a diameter of about 320 m and a rotational period of about 2 hours. The analysis of the results obtained by our complete survey have shown that (144898) 2004 VD17 is a peculiar NEO, since it is close to the breakup limits for fast rotator asteroids, as defined by Pravec and Harris (2000). These results suggest that a more robust structure must be expected, as a fractured monolith or a rubble pile in a "strength regime" (Holsapple 2002).Comment: 32 pages, 7 figure, paper accepted for publication in Icaru

Differential expression analysis with global network adjustment

<p>Background: Large-scale chromosomal deletions or other non-specific perturbations of the transcriptome can alter the expression of hundreds or thousands of genes, and it is of biological interest to understand which genes are most profoundly affected. We present a method for predicting a gene’s expression as a function of other genes thereby accounting for the effect of transcriptional regulation that confounds the identification of genes differentially expressed relative to a regulatory network. The challenge in constructing such models is that the number of possible regulator transcripts within a global network is on the order of thousands, and the number of biological samples is typically on the order of 10. Nevertheless, there are large gene expression databases that can be used to construct networks that could be helpful in modeling transcriptional regulation in smaller experiments.</p> <p>Results: We demonstrate a type of penalized regression model that can be estimated from large gene expression databases, and then applied to smaller experiments. The ridge parameter is selected by minimizing the cross-validation error of the predictions in the independent out-sample. This tends to increase the model stability and leads to a much greater degree of parameter shrinkage, but the resulting biased estimation is mitigated by a second round of regression. Nevertheless, the proposed computationally efficient “over-shrinkage” method outperforms previously used LASSO-based techniques. In two independent datasets, we find that the median proportion of explained variability in expression is approximately 25%, and this results in a substantial increase in the signal-to-noise ratio allowing more powerful inferences on differential gene expression leading to biologically intuitive findings. We also show that a large proportion of gene dependencies are conditional on the biological state, which would be impossible with standard differential expression methods.</p> <p>Conclusions: By adjusting for the effects of the global network on individual genes, both the sensitivity and reliability of differential expression measures are greatly improved.</p&gt

Florida\u27s Cattle Culture: Ethos And Enterprise In The Sunshine State

Cattle ranching has been of major significance to Florida since the 16th century; however, few are aware of the historic, ecologic, economic and cultural influence of this industry. This study investigates the origins and impacts of the traditional customs and practices of Florida’s cattle ranchers, who preserve and reinvent this rich heritage today. Ranchers live closely with the land and their animals and, due to the often-uncertain and cyclical nature of the business, must possess resourcefulness and initiative to prosper. The image of the stoic cowboy has long been associated with the American West, yet before longhorn cattle ever crossed the western plains, Florida frontiers were populated with herds of unique “cracker” cows, descendants of cattle left behind by early Spanish settlers. Like the West, Florida experienced conflicts between ranchers and other land claimants, issues that continue in the 21st century. Modern ranchers contend with developers, environmental concerns, and increasing regulation, yet they persevere in passing on their cultural heritage. Agricultural lifestyles can be emotionally fulfilling, but stewardship of land and animals can be stressful and labor-intensive. Motivation to continue these customs may be enhanced by identification with cowboys of popular American media, enhanced by physical immersion in a similar setting. Optimal agricultural practices have been well researched; however, anthropology provides a useful lens to examine customs and practices of Florida’s cattle ranchers. Anthropologists have long been concerned with the dynamic relationship between human culture and the environment, examining how the physical landscape and ecological niches shape and are shaped by those who inhabit them. As globalized trade markets, technology, and economies expand, influencing agricultural practices and destroying natural habitats, diachronic studies of changing environments, economic and sociocultural influences in geographically bounded locales can be helpful in understanding this process. iv However, a key consideration is the fact that culture is not static, but ever changing, thus the most important aspects of tradition and heritage that we choose to retain and reinvent may provide the most telling insight into any societ

A revised asteroid polarization-albedo relationship using WISE/NEOWISE data

We present a reanalysis of the relationship between asteroid albedo and polarization properties using the albedos derived from the Wide-field Infrared Survey Explorer. We find that the function that best describes this relation is a three-dimensional linear fit in the space of log(albedo)-log(polarization slope)-log(minimum polarization). When projected to two dimensions the parameters of the fit are consistent with those found in previous work. We also define p* as the quantity of maximal polarization variation when compared with albedo and present the best fitting albedo-p* relation. Some asteroid taxonomic types stand out in this three-dimensional space, notably the E, B, and M Tholen types, while others cluster in clumps coincident with the S- and C-complex bodies. We note that both low albedo and small (D<30 km) asteroids are under-represented in the polarimetric sample, and we encourage future polarimetric surveys to focus on these bodies.Comment: 16 pages, Accepted to Ap

Earth-Moon Impacts at ~300 Ma and ~500 Ma Ago

Impact events have played an important role in the evolution of planets and small bodies in the Solar System. Meteorites, lunar melt rocks, and lunar impact glasses provide important information about the geology of the parent body and the age of the impacting episodes. Over 2400 impact glasses from 4 Apollo regolith samples have been geochemically analyzed and a subset has been dated by the (40)Ar/(39)Ar method. New results, consistent with 2 break-ups in the Asteroid Belt, are presented here. Our previous study reported that (40)Ar/(39)Ar ages from 9 impact glasses showed that the Moon experienced significant impacts at approx. 800 Ma and at approx. 3800 Ma ago, somewhere in the vicinity of the Apollo 16 landing site. Additionally, reported on Apollo 12 samples with ages around 800 Ma, together implying global bombardment events. New data on 7 glasses from regolith sample 66041,127 show that the Moon also experienced impact events at approx. 300 Ma and > 500 Ma ago, which may coincide with the break-ups in the Asteroid Belt of the L- and H-chrondrite parent bodies. Since meteoritic evidence for these breakups has been found on Earth, it follows that evidence should be found in lunar samples as well. Additional information is included in the original extended abstract

A simultaneous equation analysis of selected terminal hog markets

For many years, terminal hog markets have served as price reflecting points for the rest of the hog economy, reflecting market conditions for hogs. During the last decade, however, the percentage of packers’ purchases made from terminal markets has declined from about thirty percent to approximately eighteen percent, while direct buying and purchases through auction markets have increased. As the volume of hogs traded in terminal markets declines, the protection of consumers' welfare, as well as that of farmers and packers, becomes increasingly important since equilibrium prices and quantities for such markets may not be competitively determined. Fresh egg markets of a few years ago offer an example of how markets can lose their role as price reflecting points when their volume of trade falls to a small percentage of total trade. In looking to the future, Breimyer (1970) emphasized the important role of terminal markets in noting that In all the economy if not all society, certain persons and institutions and practices become virtually a proxy for a larger body... In livestock marketing, there must be a central value determining mechanism if we are to have an exchange system. Total decentralization is bedlam and unworkable. Even as central markets fade out of the limelight, I find it necessary to defend their significant role. They have served as the price making mechanism, or a big part of it, for a much larger volume of trading than actually takes place on the markets themselves. In spite of their importance, terminal hog markets have received little attention separate from the rest of the hog economy. Although the relative volume handled by terminal markets has been declining, their role in the pricing of hogs may even be increasing. For example, production of slaughter hogs has become and is becoming more coordinated and integrated vertically. A current form of closer coordination in the production and marketing of hogs are contractual agreements between producers of hogs and various corporations. These contracts differ depending upon whom the contracting corporation is, but the general purpose of the contracts is to stabilize hog supplies so that the buyers and sellers may operate under less uncertainty, whether the buyer be a feed manufacturer or a packer. Diverse as these contracts may be, they usually involve at some stage of production the purchase or sale of hogs whose price is determined by the current slaughter hog price at a specified terminal market. As the incidence of such agreements increases, the importance of terminal markets as price reflecting points may be expected to increase. Should the importance of terminal hog markets in the value determining mechanism increase, should these markets become proxies for many buyers and sellers, understanding the structure of these markets may become crucial to the protection of consumers’ welfare. This study sought to help provide such an understanding. The purpose of this paper was to describe the structure of demand and supply for slaughter hogs, on a monthly basis, at eight terminal markets. Structure was used in an econometric sense, i.e., a model with each equation representing an autonomous sector of an economic problem, such as demand and supply, with parameters having specific values. The markets studied were Chicago, Indianapolis, Kansas City, Omaha, St. Louis, Sioux City, South St. Joseph, and South St. Paul. An effort was made to specify demand and supply relationships in accordance with those established in the agricultural economics literature, so that the usefulness of these relationships in understanding the monthly behavior of terminal markets might be determined empirically. This literature is surveyed in the following chapter. In accordance with this literature, a model of the demand for and supply of slaughter hogs is presented in Chapter III. For each of the eight markets, demand and supply equations were estimated by applying three-stage least squares to the principal components of the predetermined variables. The theory behind this estimation procedure is presented in Chapter IV. Then in Chapter V, the results of the analysis are presented, followed by conclusions in Chapter VI.Includes bibliographical references