The Occupations of Slaves Sold in New Orleans: Missing Values, Cheap Talk, or Informative Advertising

Although plantation records indicate that many slaves in the southern United States were artisans and craftsmen, relatively few slaves were recorded as such on the New Orleans sales invoices. Robert Fogel (1989, p.57, 162) assumes that the slaves without recorded occupations were unskilled workers,concluding that skilled slaves were "less than half as likely to have been sold as were ordinary field hands." Using data from New Orleans newspapers, we find that most sales advertisements include information about the slave's skill or occupation. A comparison of the advertisement with the corresponding invoice shows that the slave's occupation was often omitted from the sales invoice. Because the slave's market price should reflect all relevant information available at the time of sale, the informational value of the slave's advertised occupation can be estimated using regression analysis. Interestingly, we find that the qualitative description of the slave's skill level affected his market price more than his advertised occupation. For example, an "excellent" cook commanded a premium price whereas a "plain" or "tolerable" cook did not. These results suggest that buyers used available information in making their bids and that newspaper advertisements were not simply "cheap talk."slavery, human capital

An investigation into the effect on skin surface temperature of three cryotherapy modalities

OBJECTIVE: To investigate the comparative cooling effect at the knee, of Crushed Ice and two commonly used commercial cryotherapy modalities, following a clinically relevant application of 20 minutes. DESIGN: Within subjects, randomised cross over design. SETTING: University Laboratory PARTICIPANTS: Eleven healthy male participants MAIN OUTCOME Measures: Skin temperature over the anterior knee measured by thermal imaging camera. RESULTS: Mean absolute baseline skin surface temperature (Tsk) was 28.4ºC (±1.2 ºC). The greatest reduction in Tsk was produced by Crushed Ice D14.6 ºC (±3.7 ºC) resulting in an absolute Tsk of 13.8 ºC; followed by Ice Man D12.3 ºC (±2.4 ºC) resulting in an absolute Tsk of 16.1ºC and then Arctic Flow D4.9 ºC (±1.3 ºC) resulting in an absolute Tsk of 23.5ºC. One-way ANOVA revealed significant differences (p<.05) between modalities for change in Tsk. CONCLUSIONS: Crushed Ice and Ice Man produced very similar results following a 20 minute application to healthy adult male knees, however only Crushed Ice resulted in a skin temperature in the desired 10-15°C therapeutic range, results for Ice Man were just above this range. The resultant skin temperature following a similar application of Arctic Flow was well above the therapeutic range

The Methane Range: Coalbed Methane Development, Sage-Grouse protection, and The Ranching Way of Life

Coalbed methane development has proliferated across much of the western United States. Campbell County, Wyoming, in the Powder River Basin is one area that has seem some of the highest amounts of this development, most of it occurring on land where the surface use is livestock grazing, resulting in conflicts over resource use. This thesis takes a grounded theory approach to understanding the meaning that the ranchers that operate on this land have attached to this development. In doing so, this paper argues that these ranchers form opinions and attitudes based on how CBM has affected “the ranching way of life” and not simply on the perceived opportunity for economic gain. It also argues that although objections raised by this population to the listing the Greater Sage-Grouse as an endangered species are largely framed as objections to the way in which scientific conclusions are drawn, this may be more representative of embedded cultural viewpoints thereby making efforts to resolve this conflict through further scientific research, futile. This paper concludes that a more collaborative approach to issues surrounding CBM may have helped to avoid much of the conflict that characterizes this issue

Genetic Diversity & Connectivity of \u3cem\u3eChasmanthium latifolium\u3c/em\u3e (Poaceae) in Pennsylvania & the Effect on Conservation Status of a Rare Species

Chasmanthium latifolium (Michx.) Yates (Poaceae) is a loosely colonial, rhizomatous, perennial grass species that lives in riparian habitats, making it fittingly referred to as river oats. Native to the southern Midwest and the eastern half of the United States, C. latifolium reaches the northeastern edge of its range in Pennsylvania. Within Pennsylvania, eleven extant C. latifolium populations are found along four waterways: the Monongahela River, the Susquehanna River, and two tributaries to the Susquehanna River. This limited state distribution exhibits an east-west disjunct distribution, where western populations are largely separated from eastern populations with one centrally located population. Between the limited distribution and number of remaining populations as well as habitat threats, C. latifolium is considered critically imperiled (S1) at the state-level by the Pennsylvania Natural Heritage Program. While western populations appear contiguous with the core distribution, central and eastern populations are separated by the Allegheny Mountain range with large distances between populations along the Susquehanna River. Because of these conservation concerns, a better understanding of the natural history and genetics of C. latifolium should prove useful for conservation practitioners. My research aims to investigate the genetic diversity and connectivity of the critically imperiled taxon to better understand the natural history of the species and develop scientifically informed conservation practices. This work utilizes a genotyping by sequencing (GBS) approach to generate genomic data for use in population genetics analyses. I found that all populations appear to be genetically healthy, with high levels of heterozygosity and no inbreeding. Western populations appear as one genetic unit with some sub-structuring, while central-eastern populations are genetically different from western populations and other populations along the Susquehanna River system. Although there is currently no evidence of inbreeding, given the genetic isolation seen within the Susquehanna River populations, inbreeding may be of concern in the future. My research provides an updated, scientifically-informed conservation status assessment of C. latifolium in Pennsylvania. This project combines rare plant surveys done by the Pennsylvania Natural Heritage Program and Western Pennsylvania Conservancy with genetic work done at Bucknell University to address broad conservation questions

The Persistence of Infectious Diseases in Metapopulations

Mathematical models provide a great deal of information about the dynamics of disease spread. In this paper, we use stochastic simulation to investigate spontaneous disease extinction and réintroduction in a SIR model. We begin by investigating path to extinction and time to extinction in single population models, and then expand to a multipopulation model linked with linear migration. We have found that in a single population model, it is more effective to use random pulse vaccinations less per year at a higher removal rate. We have expanded this result by developing a vaccination strategy giving one large, well timed pulse to bring dieout within one oscillation. We then extended these methods to multipopulations to analyze the sustainability of extinction in one population. Through this, we found a means of optimally distributing a limited childhood vaccination supply in two populations. We then generalized the model for n populations and described how to simulate for different topologies. A more complete understanding of disease dynamics will enable us to develop better vaccination strategies and protect communities from infection

Concurrent printing and thermographing for rapid manufacturing: executive summary

The objective of the work was to develop systems of solid free form (SFF) manufacture capable of being used for mass production as well as for rapid prototyping (RP). Existing commercial RP systems are far too slow for mass production and are limited in the range of materials they can use. This restricts them to specialised applications and the production of prototypes. Literature search, followed by analysis and assessment pointed to printing and thermography as the most suitable technologies for further investigation. A major aim was to take advantage of existing technologies as far as possible. The main components of a prototype system were then analysed in order to identify necessary adaptations and improvements. This generated a number of highly innovative developments that were then combined to produce a system involving concurrent printing, thermographing, annealing, stacking, registering, bonding and height adjustment of coatings (SFF layers) to form parts. To confirm the level of innovation and likely future development, assessment was made of current developments in the field of SFF manufacture and printing. Prospects for commercialisation were identified by reference to extensive market research relating to the system. The concurrency of the system allows it to be substantially faster than commercial systems that are largely consecutive in their modes of operation (between 150 and 800 times faster than an SLA 5000). The use of the thermography allows a high deposition rate of a wide range of materials including thermopolymers, thermosets, metals, ceramics and glass. These advantages make the system very suitable for mass-production. Financially, the system is likely to be relatively inexpensive (around £6,000 compared with £327,300 for an SLA 5000), since it makes use of existing highly developed and readily available technologies. Several of these inventions have been patented and a company, “Rapid Manufacturing Systems Limited” has now been formed to exploit the innovations

The fate of ethane in Titan's hydrocarbon lakes and seas

Ethane is expected to be the dominant photochemical product on Titan's surface and, in the absence of a process that sequesters it from exposed surface reservoirs, a major constituent of its lakes and seas. Absorption of Cassini's 2.2 cm radar by Ligeia Mare however suggests that this north polar sea is dominated by methane. In order to explain this apparent ethane deficiency, we explore the possibility that Ligeia Mare is the visible part of an alkanofer that interacted with an underlying clathrate layer and investigate the influence of this interaction on an assumed initial ethane-methane mixture in the liquid phase. We find that progressive liquid entrapment in clathrate allows the surface liquid reservoir to become methane-dominated for any initial ethane mole fraction below 0.75. If interactions between alkanofers and clathrates are common on Titan, this should lead to the emergence of many methane-dominated seas or lakes.Comment: Accepted for publication in Icaru

Radar sounding using the Cassini altimeter waveform modeling and Monte Carlo approach for data inversion observations of Titan's seas

Recently, the Cassini RADAR has been used as a sounder to probe the depth and constrain the composition of hydrocarbon seas on Saturn's largest moon, Titan. Altimetry waveforms from observations over the seas are generally composed of two main reflections: the first from the surface of the liquid and the second from the seafloor. The time interval between these two peaks is a measure of sea depth, and the attenuation from the propagation through the liquid is a measure of the dielectric properties, which is a sensitive property of liquid composition. Radar measurements are affected by uncertainties that can include saturation effects, possible receiver distortion, and processing artifacts, in addition to thermal noise and speckle. To rigorously treat these problems, we simulate the Ku-band altimetry echo received from Titan's seas using a two-layer model, where the surface is represented by a specular reflection and the seafloor is modeled using a facet-based synthetic surface. The simulation accounts for the thermal noise, speckle, analog-to-digital conversion, and block adaptive quantization and allows for possible receiver saturation. We use a Monte Carlo method to compare simulated and observed waveforms and retrieve the probability distributions of depth, surface/subsurface intensity ratio, and subsurface roughness for the individual double-peaked waveform of Ligeia Mare acquired by the Cassini spacecraft in May 2013. This new analysis provides an update to the Ku-band attenuation and results in a new estimate for its loss tangent and composition. We also demonstrate the ability to retrieve bathymetric information from saturated altimetry echoes acquired over Ontario Lacus in December 2008

A METHOD COMPARISON STUDY OF ACCELEROMETER BASED BLOCK RESPONSE TIMES IN SPRINTING

This study aimed to provide a method comparison of a rail mounted accelerometer for detection of block response-times (RT) with an International Association of Athletic Federation (IAAF) approved automatic start control system (IAAF RT). Twenty national and international sprinters completed sprint trials under simulated race conditions. An accelerometer was placed on the block rail of blocks and RT was determined using visual inspection of the accelerometer signal and using a 3SD threshold method. On average, the visual method detected the RT event 7 ms before, and the 3SD method detected RT 1 ms after the IAAF RT. The results indicated close agreement between the 3SD threshold method and the IAAF RT, however, this highlights the need for further re-examination of threshold-based detection algorithms which may delay the detection of the RT event