Process design for the oxidation of fluorobenzene to fluorocatechol using Pseudomonas putida ML2

In this thesis, a framework for biotransformation process design has been outlined. A particular biotransformation (the microbial oxidation of fluorobenzene to fluorocatechol) was chosen to illustrate the benefits of adopting such a structured approach. This reaction system is characterized by the following: Fluorobenzene (the poorly aqueous soluble, volatile substrate) causes reversible, cellular activity inhibition at 0.8g/L. First order kinetics are observed for fluorobenzene conversion up to 0.1g/L, after which, zero order kinetics apply. Fluorocatechol (the completely aqueous soluble product) is toxic at 0.2g/L causing irreversible activity loss. An assay capable of measuring the intrinsic biocatalytic activity of the cells has been developed. These characterization data have been used to define a number of process options. One of these has been developed to promote production levels up to seventy times the cellular toxicity limit of the biocatalyst (0.185g fluorocatechol/g dry wt/hr) for 11 hours operation. Ten modes of oxygen supply were evaluated including a novel membrane oxygenator, a perfluorocarbon, a solvent, head pressurisation and oxygen enrichment. Two modes (membrane oxygenator and pure oxygen) were analysed during continuous biotransformations for their ability to eliminate fluorobenzene volatilization loss. The membrane oxygenator completely eliminated all fluorobenzene loss from the biotransformation. 13 conclusions have been drawn which are listed on page 120. By adopting the biotransformation process design framework presented in this thesis, a bioreactor configuration has been developed which has successfully overcome the difficulties associated with oxygen supply to a whole cell catalysed, aromatic oxidation having a volatile, inhibitory, poorly aqueous soluble substrate and a toxic, completely aqueous soluble product

Measuring the spin of black holes in binary systems using gravitational waves

Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions, and the opportunity of measuring spins directly through GW observations. In this letter we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientation, and signal-to-noise ratio. We find that spin magnitudes and tilt angles can be estimated to accuracy of a few percent for neutron star--black hole systems and $\sim$ 5-30% for black hole binaries. In contrast, the difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum, and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that the measurement of black hole spin by means of GWs can be as precise as what can be obtained from X-ray binaries.Comment: 4 figures, Version accepted for publication on PR

Parameter estimation for heavy binary-black holes with networks of second-generation gravitational-wave detectors

The era of gravitational-wave astronomy has started with the discovery of the binary black hole coalescences (BBH) GW150914 and GW151226 by the LIGO instruments. These systems allowed for the first direct measurement of masses and spins of black holes. The component masses in each of the systems have been estimated with uncertainties of over 10\%, with only weak constraints on the spin magnitude and orientation. In this paper we show how these uncertainties will be typical for this type of source when using advanced detectors. Focusing in particular on heavy BBH of masses similar to GW150914, we find that typical uncertainties in the estimation of the source-frame component masses will be around 40\%. We also find that for most events the magnitude of the component spins will be estimated poorly: for only 10\% of the systems the uncertainties in the spin magnitude of the primary (secondary) BH will be below 0.7 (0.8). Conversely, the effective spin along the angular momentum can be estimated more precisely than either spins, with uncertainties below 0.16 for 10\% of the systems. We also quantify how often large or negligible primary spins can be excluded, and how often the sign of the effective spin can be measured. We show how the angle between the spin and the orbital angular momentum can only seldom be measured with uncertainties below 60$^\circ$. We then investigate how the measurement of spin parameters depends on the inclination angle and the total mass of the source. We find that when precession is present, uncertainties are smaller for systems observed close to edge-on. Contrarily to what happens for low-mass, inspiral dominated, sources, for heavy BBH we find that large spins aligned with the orbital angular momentum can be measured with small uncertainty. We also show how spin uncertainties increase with the total mass. Finally...Comment: 18 pages, 28 figures. The abstract is cut in the Arxiv metadata. Refer to PDF. Version accepted by PR

Three Dimensional Structure and Energy Balance of a Coronal Mass Ejection

The Ultraviolet Coronagraph Spectrometer (UVCS) observed Doppler shifted material of a partial Halo Coronal Mass Ejection (CME) on December 13 2001. The observed ratio of [O V]/O V] is a reliable density diagnostic important for assessing the state of the plasma. Earlier UVCS observations of CMEs found evidence that the ejected plasma is heated long after the eruption. We have investigated the heating rates, which represent a significant fraction of the CME energy budget. The parameterized heating and radiative and adiabatic cooling have been used to evaluate the temperature evolution of the CME material with a time dependent ionization state model. The functional form of a flux rope model for interplanetary magnetic clouds was also used to parameterize the heating. We find that continuous heating is required to match the UVCS observations. To match the O VI-bright knots, a higher heating rate is required such that the heating energy is greater than the kinetic energy. The temperatures for the knots bright in Ly$\alpha$ and C III emission indicate that smaller heating rates are required for those regions. In the context of the flux rope model, about 75% of the magnetic energy must go into heat in order to match the O VI observations. We derive tighter constraints on the heating than earlier analyses, and we show that thermal conduction with the Spitzer conductivity is not sufficient to account for the heating at large heights.Comment: 40 pages, 16 figures, accepted for publication in ApJ For associated mpeg file, please see https://www.cora.nwra.com/~jylee/mpg/f5.mp

An exploration of the cognitive processes of design teams to inform design education and practice

While design is associated with novelty and creativity, few studies have explored the cognitive processes employed during team interactions. Design practice is collaborative where designers work in multidisciplinary teams. Along with the cognitive skills involved in designing, designers also need skills to work in teams, share information, and negotiate decisions. The aim of this study is to understand the cognitive processes used by design teams during the early phases of product design.  This study uses case studies and applies content analysis to examine the conversations of design teams during the problem definition, ideation, and concept development phases of the design process. Creativity has been described in terms of sudden bursts of ideas described as creative leaps and is associated with creative thinking. The findings in this study shows that while creative thinking is essential to creative teams, other cognitive modes such as knowledge processing, critical thinking, and metacognition are engaged in more frequently.  The emphasis of each cognitive process also varies depending on the phase of the design process. These findings have implications for how design students are educated, the skills required and how we promote creativity in design teams

Climate Impacts of Cultured Meat and Beef Cattle

Improved greenhouse gas (GHG) emission efficiency of production has been proposed as one of the biggest potential advantages of cultured meat over conventional livestock production systems. Comparisons with beef are typically highlighted, as it is a highly emissions intensive food product. In this study, we present a more rigorous comparison of the potential climate impacts of cultured meat and cattle production than has previously been made. Warming impacts are evaluated using a simple climate model that simulates the different behaviors of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), rather than relying on carbon dioxide equivalent (CO2e) metrics. We compare the temperature impact of beef cattle and cultured meat production at all times to 1,000 years in the future, using four synthetic meat GHG footprints currently available in the literature and three different beef production systems studied in an earlier climate modeling paper. Cattle systems are associated with the production of all three GHGs above, including significant emissions of CH4, while cultured meat emissions are almost entirely CO2 from energy generation. Under continuous high global consumption, cultured meat results in less warming than cattle initially, but this gap narrows in the long term and in some cases cattle production causes far less warming, as CH4 emissions do not accumulate, unlike CO2. We then model a decline in meat consumption to more sustainable levels following high consumption, and show that although cattle systems generally result in greater peak warming than cultured meat, the warming effect declines and stabilizes under the new emission rates of cattle systems, while the CO2 based warming from cultured meat persists and accumulates even under reduced consumption, again overtaking cattle production in some scenarios. We conclude that cultured meat is not prima facie climatically superior to cattle; its relative impact instead depends on the availability of decarbonized energy generation and the specific production systems that are realized

Comparison of White Crappie Populations in Diked and Undiked Lake Erie Wetlands

Author Institution: School of Natural Resources, The Ohio State UniversityMost of Ohio's remaining Lake Erie wetlands are diked to enhance habitat diversity. There is concern that fish communities in these wetlands may be isolated from adjacent waters. However, little data are available with which to evaluate possible isolation. We conducted a study that examined spring length frequencies, age structure, and growth of white crappie (Pomoxis annularis) populations in 3 diked wetlands and 2 undiked, adjacent areas. If populations are not isolated then differences in population parameters between the two types of systems should not be evident. White crappies were collected in April-May 1987 using trap nets. Length frequencies of white crappies were not similar between diked wetlands and adjacent areas, and mean lengths were significantly less in the diked wetlands. Populations were not comprised of similar age classes in the 5 systems. White crappies in diked wetlands grew significantly slower than their conspecifics in the undiked areas. These data indicate that white crappies hi diked wetlands are isolated from populations in undiked areas even though up to 75% of water in diked wetlands can be exchanged each year