Small-scale star formation at low metallicity

Massive star formation in a low metallicity environment is investigated by studying the morphology of small HII regions in the Small Magellanic Cloud. A classification scheme based upon the symmetry of form in the light of H-alpha is proposed to make possible an examination of the properties of blister candidates with respect to nebulas embedded in a more uniform medium. A new diagnostic of size is developed to derive quantitative information about the ionized gas and ionizing stars. The asymmetrical surface-brightness distribution of many HII regions demonstrates that massive stars often form at the edge of dense neutral clouds. However, the existence of many symmetrical nebulas with similar sizes, luminosities, and surface brightnesses shows that massive star formation often occurs within these clouds. Nevertheless, the statistics of the two different forms indicate that the rate of massive star formation declines less steeply with radius across host clouds than in the Milky Way, suggesting that external triggering may play a larger role in initiating star formation

Mozart’s Jewish Librettist: A Brief History of a Poorly Kept Secret

Lorenzo da Ponte, the librettist of Mozart’s three greatest Italian operas, was born a Jew, a fact rumored about during his lifetime but not definitively established until 1900. The treatment (or not) of Da Ponte’s Jewish origins as documented from his time to the present constitutes a history of concealment, rumor, discovery, denigration, and exploitation. Its nadir was reached during the Nazi period, its zenith most recently, as the poet, hitherto a secondary player in the Mozart biographies, has emerged as the colorful protagonist in substantial biographies of his own

Landscape Architecture History: A Critical Review of its Curriculum and Teaching Methodology

The purpose of this thesis is to develop criteria for establishing an effective course in teaching history of landscape architecture. Believing that professors, students and practicing landscape architects all have justifiable concerns and comments as to the way history of landscape architecture should be taught, questionnaires were sent to each of these groups across the country. Based on the responses to the questionnaires, coupled with information gleaned from a review of literature and the author\u27s personal teaching experiences, the course criteria is established. The research showed that it is important that the instructor be able to select historic periods and projects which he can effectively express in designer \u27 s terms. Thus, rather than outlining a detailed course curriculum, the thesis presents guide-lines for selecting course material, as well as suggestions for effective teaching methods

Theology of Brotherly Love

Is it possible to have an adverse experience with Christianity and emerge being empowered by a new understanding of the gospel? Howard Thurman seems to answer that question in the affirmative. Thurman analyzes comments from Mahatma Gandhi and a barrister from India about Christianity under the light of the gospel. This encounter was important. It was the Genesis of Thurman\u27s theology of brotherly love. This paper is an historical analysis of Howard Thurman\u27s struggle to resolve the conflict between the perception that Christianity is a white man\u27s religion and the gospel of Jesus and the disinherited. The writer will discuss Thurman\u27s belief in Christian community and the true Christian message. Additionally, this research examines how Thurman combined his recognition of Jesus being the subject of religious worship, with his view that mysticism was an agent that leads to social change. Finally, we will explore Thurman\u27s emerging theology of brotherly love. We will see that the linchpin behind Thurman\u27s theology is Jesus, the potent and affirming Messiah. Jesus and his examples of how to love the disinherited demonstrate that the love of Christ is the element that will bring about healing, wholeness and unity to Christians and to the world

Theology of Brotherly Love

Is it possible to have an adverse experience with Christianity and emerge being empowered by a new understanding of the gospel? Howard Thurman seems to answer that question in the affirmative. Thurman analyzes comments from Mahatma Gandhi and a barrister from India about Christianity under the light of the gospel. This encounter was important. It was the Genesis of Thurman\u27s theology of brotherly love. This paper is an historical analysis of Howard Thurman\u27s struggle to resolve the conflict between the perception that Christianity is a white man\u27s religion and the gospel of Jesus and the disinherited. The writer will discuss Thurman\u27s belief in Christian community and the true Christian message. Additionally, this research examines how Thurman combined his recognition of Jesus being the subject of religious worship, with his view that mysticism was an agent that leads to social change. Finally, we will explore Thurman\u27s emerging theology of brotherly love. We will see that the linchpin behind Thurman\u27s theology is Jesus, the potent and affirming Messiah. Jesus and his examples of how to love the disinherited demonstrate that the love of Christ is the element that will bring about healing, wholeness and unity to Christians and to the world

Mutations in the TolC periplasmic domain affect substrate specificity of the AcrAB-TolC pump

TolC and the other members of the outer membrane factor (OMF) family are outer membrane proteins forming trimeric channels that serve as a conduit for most actively effluxed substrates in Gram-negative bacteria by providing a key component in a multitude of tripartite efflux-pumps. Current models of tripartite pump assembly ascribe substrate selection to the inner-membrane transporter and periplasmic-adapter protein (PAP) assembly, suggesting that TolC is a passive, non-selective channel. While the membrane-embedded portion of the protein adopts a porin-like fold, the periplasmic domain of TolC presents a unique “alpha-barrel” architecture. This alpha-barrel consists of pseudo-continuous α-helices forming curved coiled-coils, whose tips form α-helical hairpins, relaxation of which results in a transition of TolC from a closed to an open-aperture state allowing effective efflux of substrates through its channel. Here, we analysed the effects of site-directed mutations targeting the alpha-barrel of TolC, of the principal tripartite efflux-pump Escherichia coli AcrAB-TolC, on the activity and specificity of efflux. Live-cell functional assays with these TolC mutants revealed that positions both at the periplasmic tip of, and partway up the TolC coiled-coil alpha-barrel domain are involved in determining the functionality of the complex. We report that mutations affecting the electrostatic properties of the channel, particularly the D371V mutation, significantly impact growth even in the absence of antibiotics, causing hyper-susceptibility to all tested efflux-substrates. These results suggest that inhibition of TolC functionality is less well-tolerated than deletion of tolC, and such inhibition may have an antibacterial effect. Significantly and unexpectedly, we identified antibiotic-specific phenotypes associated with novel TolC mutations, suggesting that substrate specificity may not be determined solely by the transporter protein or the PAP, but may reside at least partially with the TolC-channel. Furthermore, some of the effects of mutations are difficult to reconcile with the currently prevalent tip-to-tip model of PAP-TolC interaction due to their location higher-up on the TolC alpha-barrel relative to the proposed PAP-docking sites. Taken together our results suggest a possible new role for TolC in vetting of efflux substrates, alongside its established role in tripartite complex assembly

Friction and Surface Damage of Several Corrosion-resistant Materials

Friction and surface damage of several materials that are resistant to corrosion due to liquid metals was studied in air. The values of kinetic friction coefficient at low sliding velocities and photomicrographs of surface damage were obtained. Appreciable surface damage was evident for all materials tested. The friction coefficients for the combinations of steel, stainless steel, and monel sliding against steel, stainless steel, nickel, Iconel, and Nichrome ranged from 0.55 for the monel-Inconel combination to 0.97 for the stainless-steel-nickel combination; for steel, stainless steel, monel, and tungsten carbide against zirconium, the friction coefficient was approximately 0.47. Lower coefficients of friction (0.20 to 0.60) and negligible surface failure at light loads were obtained with tungsten carbide when used in combination with various plate materials