1,729 research outputs found
Catalytic hydroprocessing of bio-oils of different types
Pyrolyse is een interessante route om vaste biomassa om te zetten in vloeibare producten. Echter de product eigenschappen van de gevormde pyrolyse oliën zijn zodanig dat deze niet direct toepasbaar zijn als transportbrandstof. Een mogelijke technologie om de producteigenschappen te verbeteren is een katalytische waterstof behandeling. Tijdens deze behandeling worden de zuurstof bevattende componenten omgezet in een mengsel van koolwaterstoffen. Dit proefschrift beschrijft onderzoek naar de omzetting van pyrolyse oliën naar transportbrandstoffen met behulp van deze katalytische waterstof behandeling. Het onderzoek was experimenteel van aard en had als doelstellingen om meer inzicht te krijgen in i) het effect van de samenstelling van de voeding op het proces en de product eigenschappen, ii) relevante moleculaire omzettingen, iii) de rol van de katalysator en met name mogelijke deactiverings routes en iv) het bepalen van proces-product relaties. De experimenten werden uitgevoerd met een aantal verschillende pyrolyse olie voedingen in continue geopereerde vaste bed reactoren in het zogenaamde trickle flow regiem. De research beschreven in dit proefschrift toont aan dat een breed scala aan pyrolyse oliën kunnen worden omgezet in koolwaterstof rijke producten met een laag zuurstofgehalte De verwerkbaarheid van de verschillende pyrolyse oliën is afhankelijk van het gehalte aan sporenelementen en de thermische stabiliteit van de voeding, die gerelateerd is aan de aanwezigheid van bepaalde geoxygeneerde componenten. De opbrengst en de samenstelling van de product oliën blijkt sterk afhankelijk te zijn van de gebruikte voedingen.One pathway from renewable biomass feedstocks to replacements for liquid fuels from fossil sources is the fast pyrolysis pathway. Catalytic hydroprocessing of fast pyrolysis bio-oil is intended to improve the fuel quality from the highly oxygenated products to a hydrocarbon mixture, which could serve as a fuel in conventional transportation systems. This thesis includes studies to advance the state of technology of bio-oil hydrotreating. This thesis describes experimental work of an applied nature with a strong under-pinning of chemical mechanistic understanding, catalytic material analysis, and fuel property considerations. The chapters describe some of the most recent efforts in converting several types of biomass fast pyrolysis bio-oils to hydrocarbon mixtures with potential use as fuel blending components. Bench-scale experiments in the hydroprocessing of a range bio-oil products including 1) conventional fluid-bed pyrolysis products, 2) hot-vapor filtered bio-oil from an entrained flow reactor, 3) fractionated bio-oil from a conventional fluid-bed reactor, 4) oil products from a bio- oil recycle system, and 5) a catalytic pyrolysis product, which is a stabilized (deoxygenated) fast pyrolysis bio-oil product are reported. The chapters of this thesis demonstrate that a range of bio-oil products can be transformed by catalytic hydrotreatment to produce primarily hydrocarbon mixtures. The different bio-oil types, which were processed, can have different results relative to ease of processing due to trace component content or thermal stability related to oxygenated component types. The products can vary based on component types as well as yield structure
Alcohol Consumption, Alcohol Outlets, and the Risk of Being Assaulted With a Gun
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65835/1/j.1530-0277.2009.00912.x.pd
Meals in western eating and drinking
Meals are a way of organizing eating into events that have a particular structure and form, and they play an indisputable and even self-evident role within the rhythms and routines of everyday life. In late modern societies, concern about the fate of meals has arisen in both public and academic discourse. It has been suggested that eating is characterized today by individualization, destructuration, and informalization and that communal meals are increasingly being replaced by snacks and solitary eating. This chapter focuses on meals in today’s affluent societies and reflects on why meals are considered important, how meals are defined, and what material elements and social dimensions they contain. It looks at how societal and cultural changes and ecological concerns may influence the organization and future of meals, and it suggests that the content of meals will change in response to the need to diminish the ecological burden of food production and consumption. In particular, plant-based options will at least partly need to replace meat and other animal-based foods. However, there is no reason to expect that the meal as a social institution will break down. Despite the fact that not all meals are characterized by conviviality and companionship, they continue to serve as a significant arena of human sociability and togetherness. Sharing food is, after all, an essential part of being human.Non peer reviewe
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Homicide and geographic access to gun dealers in the United States
<p>Abstract</p> <p>Background</p> <p>Firearms are the most commonly used weapon to commit homicide in the U.S. Virtually all firearms enter the public marketplace through a federal firearms licensee (FFL): a store or individual licensed by the federal government to sell firearms. Whether FFLs contribute to gun-related homicide in areas where they are located, in which case FFLs may be a homicide risk factor that can be modified, is not known.</p> <p>Methods</p> <p>Annual county-level data (1993–1999) on gun homicide rates and rates of FFLs per capita were analyzed using negative binomial regression controlling for socio-demographic characteristics. Models were run to evaluate whether the relation between rates of FFLs and rates of gun homicide varied over the study period and across counties according to their level of urbanism (defined by four groupings, as below). Also, rates of FFLs were compared against FS/S – which is the proportion of suicides committed by firearm and is thought to be a good proxy for firearm availability in a region – to help evaluate how well the FFL variable is serving as a way to proxy firearm availability in each of the county types of interest.</p> <p>Results</p> <p>In major cities, gun homicide rates were higher where FFLs were more prevalent (rate ratio [RR] = 1.70, 95% CI 1.03–2.81). This association increased (p < 0.01) from 1993 (RR = 1.69) to 1999 (RR = 12.72), due likely to federal reforms that eliminated low-volume dealers, making FFL prevalence a more accurate exposure measure over time. No association was found in small towns. In other cities and in suburbs, gun homicide rates were significantly lower where FFLs were more prevalent, with associations that did not change over the years of the study period. FFL prevalence was correlated strongly (positively) with FS/S in major cities only, suggesting that the findings for how FFL prevalence relates to gun homicide may be valid for the findings pertaining to major cities but not to counties of other types.</p> <p>Conclusion</p> <p>Modification of FFLs through federal, state, and local regulation may be a feasible intervention to reduce gun homicide in major cities.</p
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Hundreds of variants clustered in genomic loci and biological pathways affect human height
Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
History, Commemoration, and Belief: Abraham Lincoln in American Memory, 1945-2001
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91765/1/Schuman-History_Commemoration_Belief.pd
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