Cellulosic Biofuels Analysis: Economic Analysis of Alternative Technologies

The passage of U.S. laws mandating and subsidizing advanced cellulosic biofuels may spur the development of a commercial cellulosic biofuels industry. However, a cellulosic industry will only develop if the overall economics including government incentives render investment in the sector attractive to private investors.This study compares the profitability of three biofuel production types: grain based ethanol, cellulosic biochemical ethanol, and cellulosic thermochemical biofuels. In order to compare the current profitability of each of the production types, the Biofuels Comparison Model (BCM) was developed. The BCM is a spreadsheet model that estimates the net present value (NPV) for each production type given input and output prices, technical, and financial assumptions. The BCM can be updated to reflect the current profitability through embedded web price links. The study finds that grain, biochemical, and thermochemical production types are all currently unprofitable when subsidies and mandates are ignored. However, the grain based ethanol process is predicted to be the most profitable (lowest loss) compared to the cellulosic biofuels. When the 2008 Farm Bill subsidies are added to the BCM, all three production types are projected to be profitable. With the addition of the different subsidies, the cellulosic biofuels are estimated to have higher NPV’s than grain based ethanol. When compared on an energy equivalent basis, the estimated cost of producing grain ethanol is $114/bbl. crude oil equivalent, biochemical ethanol$141/bbl., and thermochemical gasoline $108/bbl.biofuels, cellulosic biofuels, corn ethanol, biofuel economics

EXIST: Mission Design Concept and Technology Program

The Energetic X-ray Imaging Survey Telescope (EXIST) is a proposed very large area coded aperture telescope array, incorporating 8m^2 of pixellated Cd-Zn-Te (CZT) detectors, to conduct a full-sky imaging and temporal hard x-ray (10-600 keV) survey each 95min orbit. With a sensitivity (5sigma, 1yr) of ~0.05mCrab (10-150 keV), it will extend the ROSAT soft x-ray (0.5-2.5keV) and proposed ROSITA medium x-ray (2-10 keV) surveys into the hard x-ray band and enable identification and study of sources ~10-20X fainter than with the ~15-100keV survey planned for the upcoming Swift mission. At ~100-600 keV, the ~1mCrab sensitivity is 300X that achieved in the only previous (HEAO-A4, non-imaging) all-sky survey. EXIST will address a broad range of key science objectives: from obscured AGN and surveys for black holes on all scales, which constrain the accretion history of the universe, to the highest sensitivity and resolution studies of gamma-ray bursts it will conduct as the Next Generation Gamma-Ray Burst mission. We summarize the science objectives and mission drivers, and the results of a mission design study for implementation as a free flyer mission, with Delta IV launch. Key issues affecting the telescope and detector design are discussed, and a summary of some of the current design concepts being studied in support of EXIST is presented for the wide-field but high resolution coded aperture imaging and very large area array of imaging CZT detectors. Overall mission design is summarized, and technology development needs and a development program are outlined which would enable the launch of EXIST by the end of the decade, as recommended by the NAS/NRC Decadal Survey.Comment: 14 pages, 8 figures, 2 tables. PDF file only. Presented at SPIE (Aug. 2002) and to appear in Proc. SPIE, vol. 485

New remarks on the Cosmological Argument

We present a formal analysis of the Cosmological Argument in its two main forms: that due to Aquinas, and the revised version of the Kalam Cosmological Argument more recently advocated by William Lane Craig. We formulate these two arguments in such a way that each conclusion follows in first-order logic from the corresponding assumptions. Our analysis shows that the conclusion which follows for Aquinas is considerably weaker than what his aims demand. With formalizations that are logically valid in hand, we reinterpret the natural language versions of the premises and conclusions in terms of concepts of causality consistent with (and used in) recent work in cosmology done by physicists. In brief: the Kalam argument commits the fallacy of equivocation in a way that seems beyond repair; two of the premises adopted by Aquinas seem dubious when the terms `cause' and `causality' are interpreted in the context of contemporary empirical science. Thus, while there are no problems with whether the conclusions follow logically from their assumptions, the Kalam argument is not viable, and the Aquinas argument does not imply a caused origination of the universe. The assumptions of the latter are at best less than obvious relative to recent work in the sciences. We conclude with mention of a new argument that makes some positive modifications to an alternative variation on Aquinas by Le Poidevin, which nonetheless seems rather weak.Comment: 12 pages, accepted for publication in International Journal for Philosophy of Religio

Influence of soil properties on archaeal diversity and distribution in the McMurdo Dry Valleys, Antarctica

Archaea are the least understood members of the microbial community in Antarctic mineral soils. Although their occurrence in Antarctic coastal soils has been previously documented, little is known about their distribution in soils across the McMurdo Dry Valleys, Victoria Land. In this study, terminal-restriction fragment length polymorphism (t-RFLP) analysis and 454 pyrosequencing were coupled with a detailed analysis of soil physicochemical properties to characterize archaeal diversity and identify environmental factors that might shape and maintain archaeal communities in soils of the three southern most McMurdo Dry Valleys (Garwood, Marshall, and Miers Valley). Archaea were successfully detected in all inland and coastal mineral soils tested, revealing a low overall richness (mean of six operational taxonomic units [OTUs] per sample site). However, OTU richness was higher in some soils and this higher richness was positively correlated with soil water content, indicating water as a main driver of archaeal community richness. In total, 18 archaeal OTUs were detected, predominately Thaumarchaeota affiliated with Marine Group 1.1b (> 80% of all archaeal sequences recovered). Less abundant OTUs (2% of all archaeal sequences) were loosely related to members of the phylum Euryarchaeota. This is the first comprehensive study showing a widespread presence and distribution of Archaea in inland Antarctic soils

Detector and Telescope Development for ProtoEXIST and Fine Beam Measurements of Spectral Response of CZT Detectors

We outline our plan to develop ProtoEXIST, a balloon-borne prototype experiment for the Energetic X-ray Imaging Survey Telescope (EXIST) for the Black Hole Finder Probe. EXIST will consist of multiple wide-field hard X-ray coded-aperture telescopes. The current design of the EXIST mission employs two types of telescope systems: high energy telescopes (HETs) using CZT detectors, and low energy telescopes (LETs) using Si detectors. With ProtoEXIST, we will develop and demonstrate the technologies required for the EXIST HETs. As part of our development efforts, we also present recent laboratory measurements of the spectral response and efficiency variation of imaging CZT detectors on a fine scale (~0.5 mm). The preliminary results confirm the need for multi-pixel readouts and small inter-pixel gaps to achieve uniform spectral response and high detection efficiency across detectors.Comment: 9 pages, 12 figures, 1 table, appears in SPIE 2005 proceedings (5898: UV, X-ray, and Gamma-ray Space Instrumentation for Astronomy XIV

Long-term capacity for organic-substrate removal by bacterial films

When wastewater is discharged to small streams, the effluent quality normally obtained from a sewage treatment plant is often not good enough to prevent serious water-quality deterioration. Hence, enhanced removal of organic pollutants is required. Efficient and economic removal of organics to very low concentrations is best achieved by biofilm processes, in which bacteria are attached to a fixed media and remove the organic compounds from the wastewater flowing past. Laboratory-scale reactors were utilized to evaluate the ability of biofilms to remove low levels of organic contaminants in water during extended operation. Nonsteady-state operation, in which trace concentrations of organic substrate were treated with a biofilm previously grown on a relatively high concentration feed, demonstrated that a slowly decaying biofilm was able to bring about high efficiency removal of the trace compound for extended periods, up to 7 months in this study. A kinetic model to describe the transient growth and decay of the biofilm was developed, and it predicted the growth and steady-state phases of the biofilm when input parameters were determined independently. The observed slow decay rate of the biofilm prolonged the usefulness of the nonsteady­state biofilm and was explained by adaptation to oligotrophic (low concentration) conditions and the growth of nitrifying bacteria which produced supplemental organic substrate to sustain the organic-utilizing bacteria. The results of this study demonstrated that nonsteady-state­biofilm processes can sustainably achieve organic concentrations much lower than conventional wastewater treatment.U.S. Department of the InteriorU.S. Geological SurveyOpe

On the Qualitative Behavior of Impurity-Based Splitting Rules I: The Minima-Free Property

We show that all strictly convex n impurity measures lead to splits at boundary points, and furthermore show that certain rational splitting rules, notably the information gain ratio, also have this property. A slightly weaker result is shown to hold for impurity measures that are only convex n, such as Inaccuracy

Role of NASA's SeaBASS Repository for the Legacy of the EXPORTS Field Biogeochemical Measurements

Role of NASA's SeaBASS repository for the legacy of the EXPORTS field biogeochemical measurements

Observational Artifacts of NuSTAR: Ghost Rays and Stray Light

The Nuclear Spectroscopic Telescope Array (NuSTAR), launched in June 2012, flies two conical approximation Wolter-I mirrors at the end of a 10.15m mast. The optics are coated with multilayers of Pt/C and W/Si that operate from 3--80 keV. Since the optical path is not shrouded, aperture stops are used to limit the field of view from background and sources outside the field of view. However, there is still a sliver of sky (~1.0--4.0 degrees) where photons may bypass the optics altogether and fall directly on the detector array. We term these photons Stray-light. Additionally, there are also photons that do not undergo the focused double reflections in the optics and we term these Ghost Rays. We present detailed analysis and characterization of these two components and discuss how they impact observations. Finally, we discuss how they could have been prevented and should be in future observatories.Comment: Published in Journal of Astronomical Telescopes, Instruments, and Systems. Open Access. http://dx.doi.org/10.1117/1.JATIS.3.4.04400