298 research outputs found

    A Professional Investigation Of The Teachers Of The Booker T. Washington And The Lincoln High Schools Of Dallas, Texas

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    Statement of Problem This problem is a study of the training, experience, teaching load, and subject combinations of the 67 teachers who filled out the questionnaire that the writer handed out in the two Negro high schools of Dallas, Texas. Primarily this study is to tell what and not why. The following are the questions which the writer has attempted to discuss in order to determine the professional status of the teachers: 1. What is the academic status of the teachers? 2. To what extent do the teachers participate in professional activities? 3. How much teaching experience have the teachers had in their present positions? 4. How much teaching experience have the teachers had in other schools? 5. How much experience have the teachers had in nonschool positions? 6. What is the teaching load of the teachers? 7. Are the teachers teaching a combination of related courses? 8. Are the teachers teaching in unrelated fields? The writer hopes to answer the foregoing questions and give some information concerning the requirements for majors and minors in the various fields. The teaching load is to be determined statistically. The professional preparation will be determined in terms of courses taken in regular college or university classes. The study will also consider membership in professional organizations, and contributions made to professional literature

    Biological, physical and morphological factors for the programming of a novel microbial hygromorphic material

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    The urgency for energy efficient, responsive architectures has propelled smart material development to the forefront of scientific and architectural research. This paper explores biological, physical, and morphological factors influencing the programming of a novel microbial-based smart hybrid material which is responsive to changes in environmental humidity. Hygromorphs respond passively, without energy input, by expanding in high humidity and contracting in low humidity.Bacillus subtilisdevelops environmentally robust, hygromorphic spores which may be harnessed within a bilayer to generate a deflection response with potential for programmability. The bacterial spore-based hygromorph biocomposites (HBCs) were developed and aggregated to enable them to open and close apertures and demonstrate programmable responses to changes in environmental humidity. This study spans many fields including microbiology, materials science, design, fabrication and architectural technology, working at multiple scales from single cells to \u27bench-top\u27 prototype.Exploration of biological factors at cellular and ultracellular levels enabled optimisation of growth and sporulation conditions to biologically preprogramme optimum spore hygromorphic response and yield. Material explorations revealed physical factors influencing biomechanics, preprogramming shape and response complexity through fabrication and inert substrate interactions, to produce a palette of HBCs. Morphological aggregation was designed to harness and scale-up the HBC palette into programmable humidity responsive aperture openings. This culminated in pilot performance testing of a humidity-responsive ventilation panel fabricated with aggregatedBacillusHBCs as a bench-top prototype and suggests potential for this novel biotechnology to be further developed

    Frobenius groups of automorphisms and their fixed points

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    Suppose that a finite group GG admits a Frobenius group of automorphisms FHFH with kernel FF and complement HH such that the fixed-point subgroup of FF is trivial: CG(F)=1C_G(F)=1. In this situation various properties of GG are shown to be close to the corresponding properties of CG(H)C_G(H). By using Clifford's theorem it is proved that the order ∣G∣|G| is bounded in terms of ∣H∣|H| and ∣CG(H)∣|C_G(H)|, the rank of GG is bounded in terms of ∣H∣|H| and the rank of CG(H)C_G(H), and that GG is nilpotent if CG(H)C_G(H) is nilpotent. Lie ring methods are used for bounding the exponent and the nilpotency class of GG in the case of metacyclic FHFH. The exponent of GG is bounded in terms of ∣FH∣|FH| and the exponent of CG(H)C_G(H) by using Lazard's Lie algebra associated with the Jennings--Zassenhaus filtration and its connection with powerful subgroups. The nilpotency class of GG is bounded in terms of ∣H∣|H| and the nilpotency class of CG(H)C_G(H) by considering Lie rings with a finite cyclic grading satisfying a certain `selective nilpotency' condition. The latter technique also yields similar results bounding the nilpotency class of Lie rings and algebras with a metacyclic Frobenius group of automorphisms, with corollaries for connected Lie groups and torsion-free locally nilpotent groups with such groups of automorphisms. Examples show that such nilpotency results are no longer true for non-metacyclic Frobenius groups of automorphisms.Comment: 31 page

    Spectral estimates of bed shear stress using suspended-sediment concentrations in a wave-current boundary layer

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    High-resolution time series of suspended-sediment profiles have been obtained using an acoustic backscatter system at an inner shelf site (North Carolina) where flows are dominated by wind-driven currents and waves. We analyzed the spatial and temporal structure of near-bed turbulence in particle-transporting flows and scalar-like fluctuations of suspended-sediment concentrations. An important element of our analysis is a new inertial dissipation method for passive tracers to estimate the shear stress acting on the seabed, using the spectral properties of suspended sediment concentrations observed by acoustic backscatter sensors. In flows that provide adequate separation of the scales of turbulence production and dissipation, a sufficiently thick constant stress wall layer, and significant sediment suspension, frequency (or associated wave number) spectra of near-bed sediment concentration exhibit a -5/3 slope in the inertial subrange that spans frequencies of order 1 Hz. This observation suggests that the suspended sediment is effectively a passive tracer of turbulent fluid motions. Inversion of the relevant, Kolmogorov scaling equations yields estimates of the shear velocity that agree reasonably well with other, independent and widely used measures. High- and low-frequency limits on application of the inertial dissipation method to sediment concentration are related to the inertial response time of sediment particles and the sediment settling timescale. We propose that, in future applications, the inertial dissipation method for passive tracers can be used to estimate either the shear velocity, effective settling velocity of suspended sediment (or equivalent particle size) or dynamic bed roughness if two of these three quantities are independently known

    Renewable energy production will exacerbate mining threats to biodiversity

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    Renewable energy production is necessary to halt climate change and reverse associated biodiversity losses. However, generating the required technologies and infrastructure will drive an increase in the production of many metals, creating new mining threats for biodiversity. Here, we map mining areas and assess their spatial coincidence with biodiversity conservation sites and priorities. Mining potentially influences 50 million km2 of Earth’s land surface, with 8% coinciding with Protected Areas, 7% with Key Biodiversity Areas, and 16% with Remaining Wilderness. Most mining areas (82%) target materials needed for renewable energy production, and areas that overlap with Protected Areas and Remaining Wilderness contain a greater density of mines (our indicator of threat severity) compared to the overlapping mining areas that target other materials. Mining threats to biodiversity will increase as more mines target materials for renewable energy production and, without strategic planning, these new threats to biodiversity may surpass those averted by climate change mitigation

    Identification des champignons pathogenes du sous-bois de Milicia spp et evaluation du comportement germinatif des graines de 39 arbres semenciers

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    L’iroko (Milicia spp.) est une espĂšce vĂ©gĂ©tale Ă  haute valeur commerciale. Cependant, elle est soumise Ă  diverses contraintes biotiques et abiotiques responsables de sa faible rĂ©gĂ©nĂ©ration naturelle. Le but de cette Ă©tude est d’identifier d’une part la mycoflore pathogĂšne du sous-bois de Milicia spp. et d’autre part, les graines Ă  bon pouvoir germinatif en vue d’amĂ©liorer les peuplements actuels. La technique de piĂ©geage des champignons utilisĂ©e dans les forĂȘts classĂ©es de Kani et de ComoĂ© 1 a montrĂ© la prĂ©sence de champignons qui appartiennent aux genres Fusarium, Phoma et Colletotrichum. Ils infectent les stades graines, 2 cotylĂ©dons et 2 feuilles de Milicia spp. Les essais germinatifs Ă  partir des graines de CĂŽte d’Ivoire et du Ghana rĂ©vĂšlent que les graines des arbres semenciers CI OK-44 et GH AB-29 se prĂȘtent bien au reboisement aussi bien en forĂȘts sĂšches que humides. Celles de GH AB-28 peuvent ĂȘtre utilisĂ©es en forĂȘt sĂšche et les graines de GH OD-1 en forĂȘt humide.Mots clĂ©s : Milicia spp., rĂ©gĂ©nĂ©ration, champignons pathogĂšnes, germination, CĂŽte d’Ivoir

    Surficial Redistribution of Fallout 131iodine in a Small Temperate Catchment

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    Isotopes of iodine play significant environmental roles, including a limiting micronutrient (127I), an acute radiotoxin (131I), and a geochemical tracer (129I). But the cycling of iodine through terrestrial ecosystems is poorly understood, due to its complex environmental chemistry and low natural abundance. To better understand iodine transport and fate in a terrestrial ecosystem, we traced fallout 131iodine throughout a small temperate catchment following contamination by the 11 March 2011 failure of the Fukushima Daiichi nuclear power facility. We find that radioiodine fallout is actively and efficiently scavenged by the soil system, where it is continuously focused to surface soils over a period of weeks following deposition. Mobilization of historic (pre-Fukushima) 137cesium observed concurrently in these soils suggests that the focusing of iodine to surface soils may be biologically mediated. Atmospherically deposited iodine is subsequently redistributed from the soil system via fluvial processes in a manner analogous to that of the particle-reactive tracer 7beryllium, a consequence of the radionuclides’ shared sorption affinity for fine, particulate organic matter. These processes of surficial redistribution create iodine hotspots in the terrestrial environment where fine, particulate organic matter accumulates, and in this manner regulate the delivery of iodine nutrients and toxins alike from small catchments to larger river systems, lakes and estuaries

    The Ideal Intersection Property for Groupoid Graded Rings

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    We show that if a groupoid graded ring has a certain nonzero ideal property, then the commutant of the center of the principal component of the ring has the ideal intersection property, that is it intersects nontrivially every nonzero ideal of the ring. Furthermore, we show that for skew groupoid algebras with commutative principal component, the principal component is maximal commutative if and only if it has the ideal intersection property

    TellEat: sharing experiences on the move

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    In a context where, due to the proliferation of mobile devices, virtual social environments on the Web are taking up a very concrete role in the way people experience their surroundings, the Future Internet seems to be headed toward a mixture of Social Web, Semantic Web and Augmented Reality. As a part of a larger project that aims at building a social network of both people and things, we designed and developed TellEat, an iPhone-based application that allows users in mobility to share facts concerning people or objects that participate in the social network, and to discover pertinent events that have been told by others. In this paper we discuss both the client application, with the interaction model and interface metaphors that have been designed to make the experience as playful as possible for users, and the server-side services that provide the necessary knowledge and reasoning mechanisms. We also present the results of preliminary tests with users
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