Liquid Hydrogen Target Experience at SLAC

Liquid hydrogen targets have played a vital role in the physics program at SLAC for the past 40 years. These targets have ranged from small "beer can" targets to the 1.5 m long E158 target that was capable of absorbing up to 800 W without any significant density changes. Successful use of these targets has required the development of thin-wall designs, liquid hydrogen pumps, remote positioning and alignment systems, safety systems, control and data acquisition systems, cryogenic cooling circuits and heat exchangers. Detailed operating procedures have been created to ensure safety and operational reliability.This paper surveys the evolution of liquid hydrogen targets at SLAC and discusses advances in several of the enabling technologies that made these targets possible

On the influence of the cosmological constant on gravitational lensing in small systems

The cosmological constant Lambda affects gravitational lensing phenomena. The contribution of Lambda to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study in the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Due to Lambda the unresolved images are slightly demagnified, the radius of the Einstein ring decreases and the time delay increases. The effect is however negligible for near lenses. In the case of null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation, references added, results unchanged, in press on PR

International Perspectives on Nonformal Education

The New England Regional Meeting of the Comparative and International Education Society was held on the campus of the University of Massachusetts, Amherst, on 3 May, 1979. The conference was co-sponsored by the Division of Community Education, Springfield College, and the Center for International Education, School of Education, University of Massachusetts. The theme of the conference was International Perspectives on Nonformal Education. The papers delivered ranged in topics from the use of traditional art forms and poetry as a medium of nonformal education to the discussion of the philosophical foundations underlying the field. Case studies of specific nonformal education projects helped to highlight the conference. A total fifteen papers were delivered, all of which are included in their original form in this document. The papers represent the views of the authors and not necessarily those of the organizers

Landesque capital as an alternative to food storage in Melanesia: Irrigated taro terraces in New Georgia, Solomon Islands

In the Pacific islands, subsistence diversity made possible continuous production of food while welldeveloped exchange networks redistributed these foodstuffs as well as items within the prestige economy. All these were aspects of the ‘storage structures’ that enabled social and nutritional value to be saved, accumulated and later mobilised. In addition, there were investments in the land, landesque capital, which secured future food surpluses and so provided an alternative to food storage, in a region where the staple foods were mostly perishable, yams excepted, and food preservation was difficult. Landesque capital included such long-term improvements to productivity as terraces, mounds, irrigation channels, drainage ditches, soil structural changes and tree planting. These investments provided an effective alternative to food storage and made possible surplus production for exchange purposes. As an example, in the New Georgia group of the western Solomon Islands irrigated terraces, termed ruta, were constructed for growing the root crop taro (Colocasia esculenta). Surplus taro from ruta enabled inland groups to participate in regional exchange networks and so obtain the shell valuables that were produced by coastal groups. In this paper, we reconstruct how this exchange system worked in New Georgia using ethno-archaeological evidence, we chart its prehistoric rise and post-colonial fall, and we outline the factors that constrained its long-term expansion.Our gratitude for support during earlier fieldwork in the New Georgia group has already been expressed in previous publications. The 2014 project was supported by the Smuts Fund and Foreign Travel Fund, University of Cambridge, and by St John’s College, Cambridge.This is the accepted manuscript. The final version is available from Maney at http://dx.doi.org/10.1179/1749631414Y.000000004