Prospects for an orbital determination and capture cell experiment

A dust experiment which combines measurements of the elemental and isotopic composition of individual particles with orbital information would contribute fundamental, new scientific information on the sources contributing to the micrometeoroid population. The general boundary conditions for such a system are: (1) it must be capable of measuring velocities in the range of 10 km/sec to 100 km/sec with several percent accuracy; (2) it must collect particles in such a way that the debris atoms are locally concentrated so that precise isotopic measurements are possible; (3) it should collect particles over a wide range of sizes starting with a lower limit of 10 microns; (4) it should incorporate materials that will not compromise the isotopic measurements; and (5) it should be large enough to obtain statistically meaningful results within a reasonable exposure time. Techniques which may satisfy these conditions are described

Pairwise Well-Formed Modes and Transformations

One of the most significant attitudinal shifts in the history of music occurred in the Renaissance, when an emerging triadic consciousness moved musicians towards a new scalar formation that placed major thirds on a par with perfect fifths. In this paper we revisit the confrontation between the two idealized scalar and modal conceptions, that of the ancient and medieval world and that of the early modern world, associated especially with Zarlino. We do this at an abstract level, in the language of algebraic combinatorics on words. In scale theory the juxtaposition is between well-formed and pairwise well-formed scales and modes, expressed in terms of Christoffel words or standard words and their conjugates, and the special Sturmian morphisms that generate them. Pairwise well-formed scales are encoded by words over a three-letter alphabet, and in our generalization we introduce special positive automorphisms of $F3$, the free group over three letters.Comment: 12 pages, 3 figures, paper presented at the MCM2017 at UNAM in Mexico City on June 27, 2017, keywords: pairwise well-formed scales and modes, well-formed scales and modes, well-formed words, Christoffel words, standard words, central words, algebraic combinatorics on words, special Sturmian morphism

Economic analysis of an integrated anthropogenic carbon dioxide network for capture and enhanced oil recovery along the Texas Gulf Coast

This paper explains the system economics of an example integrated network that uses anthropogenic CO2 from Texas Gulf Coast fossil power plants for enhanced oil recovery (EOR). These CO2 sources and sinks are connected via a pipeline network. A discounted cash flow model indicates that for all candidate oil fields that require less than an estimated $10/BBL in EOR capital expenditure, all three entities (CO2 capture, pipelines, and EOR operators) can have 20$55 per tonne of CO2 and $56 per barrel of oil. These results include no existing or future tax incentives, and there are some costs not yet included. However, a Monte Carlo analysis shows insight by indicating that the total system rate of return is most sensitive to oil production parameters. Oil price and estimated amount of recoverable oil are the most positively influential factors while the EOR capital cost is the most negatively sensitive factor. The capital costs of capture and CO2 price are less sensitive, both negatively affecting rate of return.Bureau of Economic Geolog

Amino acids and amino sugars in calcified tissues of portunid crabs

Amino acid and amino sugar in calcified tissues of portunid crab

Spatial Models to Account for Variation in Observer Effort in Bird Atlases

To assess the importance of variation in observer effort between and within bird atlas projects and demonstrate the use of relatively simple conditional autoregressive (CAR) models for analyzing grid-based atlas data with varying effort. Pennsylvania and West Virginia, United States of America. We used varying proportions of randomly selected training data to assess whether variations in observer effort can be accounted for using CAR models and whether such models would still be useful for atlases with incomplete data. We then evaluated whether the application of these models influenced our assessment of distribution change between two atlas projects separated by twenty years (Pennsylvania), and tested our modeling methodology on a state bird atlas with incomplete coverage (West Virginia). Conditional Autoregressive models which included observer effort and landscape covariates were able to make robust predictions of species distributions in cases of sparse data coverage. Further, we found that CAR models without landscape covariates performed favorably. These models also account for variation in observer effort between atlas projects and can have a profound effect on the overall assessment of distribution change. Accounting for variation in observer effort in atlas projects is critically important. CAR models provide a useful modeling framework for accounting for variation in observer effort in bird atlas data because they are relatively simple to apply, and quick to run

Plasma enhanced chemical vapour deposition of thin carbon films

There have been considerable developments in the field of hard cartxm thin film deposition in the past decade. The films show properties of extreme hardness, chemical inertness and optical transparency and their use has been suggested for wear protective coatings. The results presented here concern the use of Plasma Enhanced Chemical Vapour Deposition (PECVD) to produce these films Details of the effects of the important deposition parameters on their mechanical properties are presented. The deposition system design and implementation are desenbed. The resultant film charactenstics are presented graphically as a function of the deposition vanables Films were produced which exhibited extreme hardness of up to 3000 Vickers. Their deposition rate was found to decrease with substrate temperature and increase with induced bias and pressure. The intrinsic stress and wear resistance were found to increase with the induced bias and substrate temperature but decreased as the pressure was increased. The film adhesion was found to improve at higher temperature and bias and also at higher pressure but films in this region were found to be of reduced hardness. The intrinsic stress and poor adhesion of carbon films were identified as the main difficulties in the application of these films as wear protective coatings Possible ways of improving these film charactenstics were investigated. The main deposition vanables of substrate temperature, induced bias and pressure were identified, along with the possible optimisation of carbon thin film charactenstics by control of the deposition environment