Seismological support for the metastable superplume model, sharp features, and phase changes within the lower mantle

Recently, a metastable thermal-chemical convection model was proposed to explain the African Superplume. Its bulk tabular shape remains relatively stable while its interior undergoes significant stirring with low-velocity conduits along its edges and down-welling near the middle. Here, we perform a mapping of chemistry and temperature into P and S velocity variations and replace a seismically derived structure with this hybrid model. Synthetic seismogram sections generated for this 2D model are then compared directly with corresponding seismic observations of P (P, PCP, and PKP) and S (S, SCS, and SKS) phases. These results explain the anticorrelation between the bulk velocity and shear velocity and the sharpness and level of SKS travel time delays. In addition, we present evidence for the existence of a D" triplication (a putative phase change) beneath the down-welling structure

Optical properties of bialkali photocathodes

The optical properties of the `bialkali' KCsSb and RbCsSb photomultiplier cathodes have been experimentally investigated in the visible range. The measurements carried out include the absolute reflectance at near-normal incidence, the polarization-dependent relative reflectance at various angles and the change in polarization upon reflection from the photocathode. These experimental inputs have been combined with a theoretical model to determine the complex refractive index of the photocathodes in the wavelength range 380 to 680 nm and their thickness. As a result of this work, we derive a model which predicts the fraction of light impinging on a photomultiplier tube that is reflected, absorbed or transmitted, as a function of wavelength and angle, and dependent on the medium to which the photomultiplier is coupled.Comment: 51 pages (double spacing), 16 figures, submitted for publication in NIM

Deep mantle structure and the postperovskite phase transition

Seismologists have known for many years that the lowermost mantle of the Earth is complex. Models based on observed seismic phases sampling this region include relatively sharp horizontal discontinuities with strong zones of anisotropy, nearly vertical contrasts in structure, and small pockets of ultralow velocity zones (ULVZs). This diversity of structures is beginning to be understood in terms of geodynamics and mineral physics, with dense partial melts causing the ULVZs and a postperovskite solid–solid phase transition producing regional layering, with the possibility of large-scale variations in chemistry. This strong heterogeneity has significant implications on heat transport out of core, the evolution of the magnetic field, and magnetic field polarity reversals

Co‐operative cross‐platform courseware development

The UKMCC (UK Mathematics Courseware Consortium) is a Consortium funded under TLTP (Training and Learning Technology Programme) to produce courseware for service mathematics teaching, using the SEFI (Société Européenne pour la Formation des Ingénieurs) syllabus. There are agreed courseware design guidelines and a simple courseware management system which allows cross‐referencing. Courseware is divided into modules, with an author as implementer for each. On any one hardware platform, a variety of authoring languages is possible. Across hardware platforms, the design guidelines ensure that conversion is possible, and will preserve look and feel. We argue here that these arrangements provide a basis for continued co‐operation between authors and future development as the technology changes

Case Not Closed: A Connecticut Family in King Leopold`s Court

Dr. Lay's article about the Democratic Republic of the Congo v. Belgium case and his student's involvement in it

Description and performance of a digital mobile satellite terminal

A major goal of the Mobile Satellite Experiment (MSAT-X) program at the Jet Propulsion Lab (JPL) is the development of an advanced digital terminal for use in land mobile satellite communication. The terminal has been developed to minimize the risk of applying advanced technologies to future commercial mobile satellite systems (MSS). Testing with existing L band satellites was performed in fixed, land mobile and aeronautical mobile environments. JPL's development and tests of its mobile terminal have demonstrated the viability of narrowband digital voice communications in a land mobile environment through geostationary satellites. This paper provides a consolidated description of the terminal architecture and the performance of its individual elements

Can a Park Statue Destabilize Northeast Asia’s Inter-State Relations?

In 1991, after fifty years of silence, the forced sexual enslavement of Korean women and girls at the hands of Japan’s Imperial Army during World War II emerged as an embarrassing blight upon Japan’s otherwise enviable profile as a political and economic miracle. The case against Japan’s alleged trafficking of women meandered through the courts of Japan and the United States. It also became an issue for United Nations Human Rights Commissioner Navi Pillay in August 2014. However, no satisfactory solution has been found. Beginning in 2005 efforts began in the United States to raise public awareness of the conditions that Korean women were subjected to at the hands of Japan. Strong resistance emerged in certain Japanese-American communities to the Korean and Korean-American accounting of events but especially from Japanese government officials who have visited the United States. Japan does not dispute that Korean women and girls served as Comfort Women; however, its disputes the methods of recruitment and the numbers of women indicated in the Korean narrative. We thus find two competing narratives, that of Japan and that of Korea, being disputed in the United States. In most places the Korean narrative has prevailed but in places such as Buena Vista, California and Queens, New York, it has not. This text argues that the “Comfort Women” controversy may undermine Korea-Japan-US relations in Northeast Asia. The President of Korea made it clear in December 2014 that relations with Japan will not improve without addressing this. This article speaks of ways to do indicating the need for an objective review of both narratives and, most likely, the articulation of an American narrative