Fringe Visibility Estimators for the Palomar Testbed Interferometer

Visibility estimators and their performance are presented for use with the Palomar Testbed Interferometer (PTI). One operational mode of PTI is single-baseline visibility measurement using pathlength modulation with synchronous readout by a NICMOS-3 infrared array. Visibility is estimated from the fringe quadratures, either incoherently, or using source phase referencing to provide a longer coherent integration time. The visibility estimators differ those used with photon-counting detectors in order to account for biases attributable to detector offsets and read noise. The performance of these estimators is affected not only by photon noise, but also by the detector read noise and errors in estimating the bias corrections, which affect the incoherent and coherent estimators differently. Corrections for visibility loss in the coherent estimators using the measured tracking jitter are also presented.Comment: PASP in press (Jan 99). 13 Pages, no figure

RATES OF RETURN TO PUBLIC AGRICULTURAL RESEARCH IN THE PRESENCE OF RESEARCH SPILLOVERS

This study uses new state data to examine the contributions of public agricultural research, extension, and infrastructure to agricultural productivity. The estimated social rates of return (which take into account spillover effects) are high and imply a need for federal or regional institutions to coordinate public agricultural research funding.Research and Development/Tech Change/Emerging Technologies,

ALTERNATIVE MEASURES OF FARM SIZE: TRENDS AND DETERMINANTS

Because of policy interest in the size distribution of farms, there is an interest in understanding the causes of changing farm sizes. This paper addresses an overlooked issue in the literature on the determinants of farm size, namely, the empirical specification of farm size. We examine 5 different size measures: acres operated, land and building value, cash receipts, cash receipts plus government payments, and a constructed measure of the rental value of farms. We graphically show the difference in trends in farm size using the various measures for the U.S. and selected states. We then discuss how the results of an analysis of the determinants of farm size depend on the farm size measure employed. The data set is a panel data set of 48 states from 1960 to 1996.Farm Management,

Learning to merge search results for efficient Distributed Information Retrieval

Merging search results from different servers is a major problem in Distributed Information Retrieval. We used Regression-SVM and Ranking-SVM which would learn a function that merges results based on information that is readily available: i.e. the ranks, titles, summaries and URLs contained in the results pages. By not downloading additional information, such as the full document, we decrease bandwidth usage. CORI and Round Robin merging were used as our baselines; surprisingly, our results show that the SVM-methods do not improve over those baselines

Onebox: Free-Text Interfaces as an Alternative to Complex Web Forms

This paper investigates the problem of translating free-text\ud queries into key-value pairs as an alternative means for searching `behind' web forms. We introduce a novel specication language for specifying free-text interfaces, and report the results of a user study where we evaluated our prototype in a travel planner scenario. Our results show that users prefer this free-text interface over the original web form and that they are about 9% faster on average at completing their search tasks

Integration, integration, integration

Last week, when Dame Louise Casey’s long-awaited review into opportunity and integration was published, it struck a chord. I’m currently volunteering for the Afghanistan and Central Asian Association, a charity set up by refugee Dr. Nooralhaq Nasimi 16 years ago. The organisation’s motto is ‘to promote British values among the refugee community’, and in the work I’ve been doing it’s become all too clear just how difficult that is going to be

Recent Changes in European Welfare State Services: A Comparison of Child Care Politics in the U.K., Sweden, Germany, and the Netherlands. CES Germany & Europe Working Papers, No. 07.6, 1997

This paper examines recent policies and politics of services, in particular child care services in European welfare states. It is argued that social (care) services are becoming an increasingly political issue in postindustrial societies and are at the very center of welfare-state restructuring. Some countries have recently developed new policy pro­ grams for child care-but there are important differences among these programs. To understand these differences as well as some common features, the paper argues that it is necessary to examine the institutional organization of child care and short-term political factors as well as the rationales articulated in political debates to support or im­ pede various policies. The paper concludes that a comprehensive system of child care provisions is still far off in most countries, despite a rhetoric of choice and postindustrial care and labor-market patterns