133 research outputs found

    Black-Scholes Equation and Heat Equation

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    First, we present and define the Black-Scholes equation which is used to model assets on the stock market. After that, we derive the heat equation that describes how the temperature increases through a homogeneous material. Finally, we detail how the two equations are related. We introduce and relate the Black-Scholes equation and Heat Equation

    2020 IGGAD Conference Program

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    Program of the 2020 IGGAD Conference: Without Borders: Tracing the Cultural, Archival, and Political African Diaspora

    2019 IGGAD Conference Program

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    Program of the 2019 IGGAD Conference: Tracing the African Diaspora: Places of Suffering, Resilience, and Reinvention

    2022 IGGAD Conference Program

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    Program of the 2022 IGGAD Conference: Who Owns This? Communities, Heritage, and Preservation

    Visual sensations which create expressions

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    This thesis consists of six paintings and twelve serigraphs dealing with free flowing forms carrying associations of color through which I have attempted to organize purely intuitive responses to different experienced situations. The six paintings are executed on stretched cotton duck canvas with acrylic polymer colors. The twelve serigraphs are printed on Vellum Bristol Board with silk screen process inks. Both the paintings and serigraphs were developed from small drawing studies enlarged by the grid method or with an opaque projector. This series of works originated from an exploration of growth patterns from which I found a suitable vehicle in motifs similar to fingerprints to carry associations of color. The paintings and serigraphs are designed to be two dimensional in character. A sense of fluctuation in movement is generated by linear elements which vary in thickness, intensity, and or value. The work leading up to this thesis exhibition has evolved from an intensive study of color and spatial relationships. I have directed my efforts to achieve the visual effects obtained from using monochromatic or analogous colors. I apply colors at chosen intervals which produce a progressive comparison; thereby creating rhythm in my paintings. The serigraphs are basically an extension of the paintings which allows me to explore new motifs and spatial relationships on a smaller scale. They are also useful to me at this point because the technique of silk screen printing is an excellent method of reproducing the design with different associations of color for possible future paintings

    Disease decreases variation in host community structure in an old-field grassland

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    Disease may modulate variation in host community structure by modifying the interplay of deterministic and stochastic processes. For instance, deterministic processes like ecological selection can benefit species less impacted by disease. When disease consistently selects for certain host species, this can reduce variation in host community composition. On the other hand, when host communities are less impacted by disease and selection is weaker, stochastic processes (e.g., drift, dispersal) may play a bigger role in host community structure, which can increase variation in structure among communities. While effects of disease on host community structure have been quantified in field experiments, few have addressed the role of disease in modulating variation in structure among host communities. To address this, we conducted a field experiment spanning three years, using a tractable system: foliar fungal pathogens in an old-field grassland community dominated by the grass Lolium arundinaceum, tall fescue. We reduced foliar fungal disease burden in replicate host communities (experimental plots in intact vegetation) in three fungicide regimens that varied in the duration of fungicide exposure and included a fungicide-free control. We measured host diversity, biomass, and variation in community structure among replicate communities. Disease reduction generally decreased plant richness and increased aboveground biomass relative to communities experiencing ambient levels of disease. Despite changes in structure of the plant communities over the experiment’s three years, the effects of disease reduction on plant richness and biomass were consistent across years. However, disease reduction did not reduce variation in host community structure, providing little evidence for ecological selection by competition or other deterministic processes. Instead, disease reduction tended to amplify variation in host community structure among replicate communities (i.e., within fungicide treatment groups), suggesting that disease diminished the degree to which host communities were structured by stochastic processes. These results of experimental disease reduction both highlight the potential importance of stochastic processes in plant communities and reveal the potential for disease to regulate variation in host community structure

    Evolution Of A Higher Intracellular Oxidizing Environment In Caenorhabditis Elegans Under Relaxed Selection

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    We explored the relationship between relaxed selection, oxidative stress, and spontaneous mutation in a set of mutation-accumulation (MA) lines of the nematode Caenorhabditis elegans and in their common ancestor. We measured steady-state levels of free radicals and oxidatively damaged guanosine nucleosides in the somatic tissues of five MA lines for which nuclear genome base substitution and GC-TA transversion frequencies are known. The two markers of oxidative stress are highly correlated and are elevated in the MA lines relative to the ancestor; point estimates of the per-generation rate of mutational decay (DM) of these measures of oxidative stress are similar to those reported for fitness-related traits. Conversely, there is no significant relationship between either marker of oxidative stress and the per-generation frequencies of base substitution or GC-TA transversion. Although these results provide no direct evidence for a causative relationship between oxidative damage and base substitution mutations, to the extent that oxidative damage may be weakly mutagenic in the germline, the case for condition-dependent mutation is advanced

    Subscale Validation of the Subsurface Active Filtration of Exhaust (SAFE) Approach to NTP Ground Testing

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    Brief History of NTP: Project Rover Began in 1950s by Los Alamos Scientific Labs (now Los Alamos National Labs) and ran until 1970s Tested a series of nuclear reactor engines of varying size at Nevada Test Site (now Nevada National Security Site) Ranged in scale from 111 kN (25 klbf) to 1.1 MN (250 klbf) Included Nuclear Furnace-1 tests Demonstrated the viability and capability of a nuclear rocket engine test program One of Kennedys 4 goals during famous moon speech to Congress Nuclear Engines for Rocket Vehicle Applications (NERVA) Atomic Energy Commission and NASA joint venture started in 1964 Parallel effort to Project Rover was focused on technology demonstration Tested XE engine, a 245-kN (55-klbf) engine to demonstrate startup shutdown sequencing. Hot-hydrogen stream is passed directly through fuel elements potential for radioactive material to be eroded into gaseous fuel flow as identified in previous programs NERVA and Project Rover (1950s-70s) were able to test in open atmosphere similar to conventional rocket engine test stands today Nuclear Furance-1 tests employed a full scrubber system Increased government and environmental regulations prohibit the modern testing in open atmosphere. Since the 1960s, there has been an increasing cessation on open air testing of nuclear material Political and national security concerns further compound the regulatory environmen

    Impact of Sleep and Circadian Disruption on Energy Balance and Diabetes: A Summary of Workshop Discussions

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    A workshop was held at the National Institute for Diabetes and Digestive and Kidney Diseases with a focus on the impact of sleep and circadian disruption on energy balance and diabetes. The workshop identified a number of key principles for research in this area and a number of specific opportunities. Studies in this area would be facilitated by active collaboration between investigators in sleep/circadian research and investigators in metabolism/diabetes. There is a need to translate the elegant findings from basic research into improving the metabolic health of the American public. There is also a need for investigators studying the impact of sleep/circadian disruption in humans to move beyond measurements of insulin and glucose and conduct more in-depth phenotyping. There is also a need for the assessments of sleep and circadian rhythms as well as assessments for sleep-disordered breathing to be incorporated into all ongoing cohort studies related to diabetes risk. Studies in humans need to complement the elegant short-term laboratory-based human studies of simulated short sleep and shift work etc. with studies in subjects in the general population with these disorders. It is conceivable that chronic adaptations occur, and if so, the mechanisms by which they occur needs to be identified and understood. Particular areas of opportunity that are ready for translation are studies to address whether CPAP treatment of patients with pre-diabetes and obstructive sleep apnea (OSA) prevents or delays the onset of diabetes and whether temporal restricted feeding has the same impact on obesity rates in humans as it does in mice
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