A critical examination of discrete lattice and dispersed barrier hardening

Critical assessment of discrete lattice and dispersed barrier hardening theories of thermally activated deformation of metal

Magnetic properties and spin waves of bilayer magnets in a uniform field

The two-layer square lattice quantum antiferromagnet with spins 1/2 shows a zero-field magnetic order-disorder transition at a critical ratio of the inter-plane to intra-plane couplings. Adding a uniform magnetic field tunes the system to canted antiferromagnetism and eventually to a fully polarized state; similar behavior occurs for ferromagnetic intra-plane coupling. Based on a bond operator spin representation, we propose an approximate ground state wavefunction which covers all phases by means of a unitary transformation. The excitations can be efficiently described as independent bosons; in the antiferromagnetic phase these reduce to the well-known spin waves, whereas they describe gapped spin-1 excitations in the singlet phase. We compute the spectra of these excitations as well as the magnetizations throughout the whole phase diagram.Comment: 12 pages, 9 figs; added references; final version as publishe

Evaluation of a closed-circuit television display in landing operations with a helicopter

Evaluating closed circuit television display in helicopter landing operation

Evaluation of a contact-analog display in landing approaches with a helicopter

Evaluation of contact analog display in landing approaches with helicopter

Discovery of large scale shock fronts correlated with the radio halo and radio relic in the A2163 galaxy cluster

Imprints of galaxy cluster formation processes are visible in the intracluster medium and can arise in shock fronts, which are detectable via discontinuities in e.g. the gas temperature and density profiles. In this study, we investigate the X-ray properties of the intracluster gas and the radio morphology of the extraordinary cluster A2163. This cluster shows an irregular morphology in various wavelengths and has one of the most luminous and extended known radio halos. Additionally, it is one of the hottest clusters known. We analyze two Suzaku observations of A2163, one in the north-east (NE) and one in the south-west (SW) direction, and use archival XMM-Newton data to remove point sources in the field of view. To compare our findings in the X-ray regime with the radio emission, we obtain radio images of the cluster from an archival VLA observation at 20cm. We identify three shock fronts in A2163 in our spectral X-ray study. A clear shock front lies in the NE direction at a distance of 1.4Mpc from the center, with a Mach number of $M=1.7_{-0.2}^{+0.3}$, estimated from the temperature discontinuity. This shock coincides with the position of a known radio relic. We identify two additional shocks in the SW direction, one with $M=1.5_{-0.3}^{+0.5}$ at a distance of 0.7Mpc, which is likely related to a cool core remnant, and a strong shock with $M=3.2_{-0.7}^{+0.6}$ at a distance of 1.3Mpc, which also closely matches the radio contours. The complex structure of A2163 as well as the different Mach numbers and shock velocities suggest a merging scenario with two unequal merging constituents, where two shock fronts emerged in an early stage of the merger and traveled outwards while an additional shock front developed in front of the merging cluster cores.Comment: 9 pages, 7 figures, accepted by A&

Serving Two Masters: Moravian Brethren in Germany and North Carolina, 1727-1801

The eighteenth century was a time of significant change in the perception of marriage and family relations, the emphasis of reason over revelation, and the spread of political consciousness. The Unity of the Brethren, known in America as Moravians, experienced the resulting tensions firsthand as they organized their protective religious settlements in Germany. A group of the Brethren who later settled in Salem, North Carolina, experienced the stresses of cultural and generational conflict when its younger members came to think of themselves as Americans. The Moravians who first immigrated to America actively maintained their connections to those who remained in Europe and gave them the authority for deciding religious, social, and governmental issues. But, as the children born in Salem became acclimated to more freedoms, particularly in the wake of the American Revolution, a series of disputes intensified the problems of transatlantic governance. While the group\u27s leadership usually associated Enlightenment principles with rebellion and religious skepticism, the younger Brethren were drawn to its message of individual autonomy and creative expression. Elisabeth Sommer traces the impact of this generational and cultural change among Moravians on both sides of the Atlantic and examines the resulting debate over the definition of freedom and faith. An important contribution to an expanding literature whose base in archival work on both sides of the Atlantic reveals the Moravian struggles to be faithful to their deepest commitments. —A.G. Roeber, Pennsylvania State University The international Moravian story is charming and powerful. . . . We are indebted to Sommer for arduous and skillful work in passing on their story to us. —American Historical Review Provides a more profound understanding of what the Moravians believed, why they came, and the process by which they increasingly accommodated to the American world. —Appalachian Quarterly A detailed and thought-provoking narrative of declension and the formation of new political identities. —Georgia Historical Quarterly Creative and well-researched. . . . Will interest a variety of scholars. —H-Net Reviews A good book that tells us much about the development of American sensibilities in an immigrant religious group and does so with a helpful transatlantic perspective. —Journal of American History Contributes significantly to our understanding of the evolution of Moravian communities and of the forces that influenced their future direction. —Journal of Southern History Gives additional depth to our comparative understanding of the social as well as the religious experience of people on two sides of the Atlantic in the eighteenth century. —Journal of the Early Republic Should prove beneficial not only to those primarily interested in Moravian studies but also to those whose field includes wider social history concerns. —North Carolina Historical Review A valuable contribution not only to the field of early American religious history, but also to the sociology of religion and Moravian and Pietist studies. —Religious Studies Review Represents the best trends in transatlantic history. . . . Invites us to search for other religious cables binding early America to a wider world. —William and Mary Quarterlyhttps://uknowledge.uky.edu/upk_history_of_religion/1004/thumbnail.jp

Geochemical and spectral characterization of naturally altered rock surfaces

The possibility of using the visible-near infrared region for compositional analysis of remotely sensed rock surfaces is studied. This would allow mapping rock type both on the Earth's surface and on other planetary surfaces. Reflectance spectroscopy, economic geology, optical depth determination, and X-ray diffraction mineralogy are discussed

Light, stratification and zooplankton as controlling factors for the spring development of phytoplankton in Lake Constance

The patterns of phytoplankton growth and decline during the spring bloom and the following clear-water phase in Lake Constance have been studied on the basis of cell counts with short-term sampling intervals and related to light climate, stratification and zooplankton pressure