106 research outputs found

    The Making of a President Using Data Analytics and Social Media

    Get PDF
    Today, political campaigns rely heavily on analytics to target potential voters. The algorithms used, as well as bias that may be introduced in the process, may skew the results and cost an election, as seen in the Clinton campaign. Additionally, Social Media plays a huge role in political races, as does fake news. More alarming is the new trend for Social Media sites to censor anyone or anything which can also make or break a campaign. In this paper we research events that affected the 2016 Presidential election and present issues that may have an effect on future elections

    Causes and consequences of coupled crystallization and vesiculation in ascending mafic magmas

    Get PDF
    Thesis (Ph.D.) University of Alaska Fairbanks, 2017Transitions in eruptive style and eruption intensity in mafic magmas are poorly understood. While silicic systems are the most researched and publicized due to their explosive character, mafic volcanoes remain the dominant form of volcanism on the earth. Eruptions are typically effusive, but changes in flow behavior can result in explosive, ash generating episodes. The efficiency of volatiles to degas from an ascending magma greatly influences eruption style. It is well known that volatile exsolution in magmas is a primary driving force for volcanic eruptions, however the roles vesicles and syn-eruptive crystallization play in eruption dynamics are poorly understood. Permeability development, which occurs when gas bubbles within a rising magma form connected pathways, has been suspected to influence eruption style and intensity. Numerous investigations on natural eruptive products, experimental samples, and analog experiments have extended the understanding of permeability development and fragmentation processes. However, these studies have focused on silicic, high viscosity, crystal-poor magmas. Little progress has been made in understanding fragmentation mechanisms in mafic or alkali magmas. Mafic systems involve lower viscosity magmas that often form small crystals, also known as microlites, during ascent. Because the merging of bubbles in magma is mitigated by melt viscosity, it is predicted that permeability development in mafic magma will occur at lower bubble volume fractions than in silicic magma. However, no study has been performed on experimental samples to provide evidence for this hypothesis. Furthermore, it is unknown how microlites affect the degassing process in terms of facilitating or hindering permeability development. This thesis employs experimental petrology to: 1) experimentally observe how melt viscosity alone affects permeability development, 2) Understand the effects of syn-eruptive crystallization in vesiculating mafic magmas and synergizes these results to 3) relate experimental findings to the 2008 eruption of Kasatochi volcano

    High Crystal Number Densities From Mechanical Damage

    Get PDF

    Melt diffusion-moderated crystal growth and its effect on euhedral crystal shapes

    Get PDF
    Crystal growth is often described as either interface-controlled or diffusion-controlled. Here, we study crystal growth in an intermediate scenario where reaction rates at the crystal-melt interface are similar to the rates of diffusive transport of ions through the melt to the advancing crystal surface. To this end, we experimentally investigated euhedral plagioclase crystal shapes in dry mafic (basaltic) and hydrous silicic (haplodacitic) melts. Aspect ratios and inferred relative growth rates of the 3D short (S) and intermediate (I) crystal dimensions vary significantly between mafic and silicic melts, with δS:δI = 1:6 – 1:20 in basalt and 1:2.5 – 1:8 in hydrous haplodacite. The lower aspect ratios of plagioclase grown in the silicic melt coincide with 10-100x lower melt diffusion rates than in the mafic melt. Using an anisotropic growth model, we show that such differences in melt diffusivity can explain the discrepancy in plagioclase aspect ratios: if interface reaction and melt diffusion rates are of similar magnitude, then the growth of a crystal facet with high interfacial reaction rates may be limited by melt diffusion while another facet of the same crystal with lower interfacial reaction rates may grow uninhibited by melt diffusivity. This selective control of melt diffusion on crystal growth rates results in progressively more equant crystal shapes as diffusivity decreases, consistent with our experimental observations. Importantly, crystals formed in this diffusion-moderated, intermediate growth regime may not show any classical diffusion-controlled growth features. The proposed model was developed for plagioclase microlites, but should be generalisable to all anisotropic microlite growth in volcanic rocks

    Transient winter leaf reddening in Cistus creticus characterizes weak (stress-sensitive) individuals, yet anthocyanins cannot alleviate the adverse effects on photosynthesis

    Get PDF
    Under apparently similar field conditions individual plants of Cistus creticus turn transiently red during winter, while neighbouring plants remain green. These two phenotypes provide a suitable system for comparing basic photosynthetic parameters and assessing critically two hypotheses, i.e. anthocyanins afford photoprotection and anthocyanins induce shade characteristics on otherwise exposed leaves. With that aim, pigment levels and in vivo chlorophyll fluorescence parameters were monitored in dark-acclimated (JIP-test) and light-acclimated (saturation pulse method) leaves during both the green and the red period of the year. No evidence for actual photoprotection by anthocyanins was obtained. On the contrary, all fluorescence parameters related to yields and probabilities of photochemical energy conversion and electron flow, from initial light trapping to final reduction of ultimate electron acceptors in PSI, declined in the red phenotype after leaf reddening. Moreover, the pool sizes of final electron acceptors of PSII diminished, indicating that both photosystems were negatively affected. Vulnerability to winter stress was also indicated by sustained chlorophyll loss, inability to increase the levels of photoprotective xanthophylls and increased quantum yield of non-regulated energy loss during reddening. However, during the same period, the relative PSII antenna size increased, indicating an apparent shade acclimation after anthocyanin accumulation, while changes in the photosynthetic pigment ratios were also compatible to the shade acclimation hypothesis. All parameters recovered to pre-reddening values upon re-greening. It is concluded that the photosynthetic machinery of the red leaf phenotype has an inherently low capacity for winter stress tolerance, which is not alleviated by anthocyanin accumulation

    Interaction and accumulation of manganese and cadmium in the manganese accumulator Lupinus albus

    Full text link
    NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Plant Physiology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Plant Physiology, 167, 13 (2010) DOI http://dx.doi.org/10.1016/j.jplph.2010.02.011The effects of the interaction between Mn and Cd on the growth of the white lupin (Lupinus albus), uptake of these metals, their accumulation, and effects on heavy metal stress indicators were studied under glasshouse conditions. Plants were grown with and without Mn and/or Cd for 4 weeks. The absence of Mn and Cd led to lipid peroxidation-induced loss of flavonoids and anthocyanins in the roots, reduced the size of the plant canopy, and led to the appearance of proteoid roots. Sensitivity to Cd in white lupin was enhanced by a low Mn supply, despite lower Cd uptake and accumulation (leaf Mn:Cd concentration ratio <3), as evidenced by increased lipid peroxidation in the leaves and strong inhibition of growth. However, when the Mn supply was adequate, the plants showed few symptoms of Cd toxicity, even though Cd uptake and accumulation increased. A Mn:Cd ratio of up to 20 was enough to minimize Cd stress in the leaf, reflecting the plants' relative tolerance to Cd under such conditions. Irrespective of the Mn supply, the increase in antioxidant compounds observed in the roots of Cd-treated plants might act as a protective mechanism by minimizing the oxidative stress caused by Cd exposure. In summary, high leaf Mn concentrations seem to render white lupins more tolerant to Cd stressThis work was funded by the Spanish Ministry of Education and Science (project CTM2005-04809/TECNO

    Translocation of zeatin riboside and zeatin in soybean explants

    Full text link
    Soybean explants consisting of a leaf, one or more young pods, and a subtending piece of stem were given a 1-h pulse of 3 H (ring-labeled)-zeatin riboside (ZR) or -zeatin (Z), via the base of the stem, followed by a 24-h incubation. At the end of the pulse, about 55% of the soluble 3 H was in the leaf blades, 11% in the petiole, 30% in the stem, 2% in the carpels, 0.1% in the seed coats, and 0.08% in the embryos. After 24 h, the percentages were 58, 7, 26, 6, 2, and 0.3, respectively. During this period, the total soluble 3 H decreased by 84%, the remainder being bound to “insoluble” material. The 3 H-cytokinin was rapidly converted to diverse metabolites including adenosine and adenine. At the end of the 1-h pulse, appreciable percentages (1–16%) of the total soluble 3 H in the seed coats chromatographed with ZR (or dihydro ZR) and with the 5′-phosphate of ZR, but these percentages declined markedly at 24 h. No distinct peaks of 3 H corresponded to known metabolites in the soluble extracts of embryos, and at 24 h, the 3 H equivalent to ZR must have been less than 0.0006% of the 3 H-ZR supplied. The bound 3 H corresponded to adenine and guanine in DNA and RNA. In contrast to cytokinin, 3 H-adenosine given as a pulse was readily translocated into the seed coats and embryos. Thus, cytokinin (ZR and Z) flowing up through the xylem from the root system does not readily enter the embryo (though metabolites such as adenosine could), and the seeds clearly do not compete with the leaves for this supply of cytokinin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45929/1/344_2005_Article_BF02042255.pd
    corecore