985 research outputs found

    Functional Sequential Treatment Allocation

    Full text link
    Consider a setting in which a policy maker assigns subjects to treatments, observing each outcome before the next subject arrives. Initially, it is unknown which treatment is best, but the sequential nature of the problem permits learning about the effectiveness of the treatments. While the multi-armed-bandit literature has shed much light on the situation when the policy maker compares the effectiveness of the treatments through their mean, much less is known about other targets. This is restrictive, because a cautious decision maker may prefer to target a robust location measure such as a quantile or a trimmed mean. Furthermore, socio-economic decision making often requires targeting purpose specific characteristics of the outcome distribution, such as its inherent degree of inequality, welfare or poverty. In the present paper we introduce and study sequential learning algorithms when the distributional characteristic of interest is a general functional of the outcome distribution. Minimax expected regret optimality results are obtained within the subclass of explore-then-commit policies, and for the unrestricted class of all policies

    Australian and US Experiences with Transfer of Rangeland Improvement Technologies: A Comparative Analysis

    Get PDF
    American and Australian range economists work in tandem with range ecologists and management specialists to develop and analyze strategies for technology transfer. Historically, this process has developed around a model aimed at communication with a narrow target group (ranchers) with easily-defined and homogeneous goals (continuously improving income). In accord with this traditional model of technology transfer, the focus of range economists’ inquiries was once to assess the cost-effectiveness of grazing improvement technologies (Conner, 1985). It is a relatively recent phenomenon that both American and Australian range technology transfer agents are encountering an increasingly broad social and ecological agenda. Ranchers recognize and respond to a variety of goals and motivations. This has implications for their decisions considering whether and when to adopt certain grazing improvement technologies. The analysis of technology transfer now involves taking a systems approach, considering a larger arena of stakeholders and their expectations concerning the sustainable use of rangelands, and, accordingly, accounting for increasingly complex and diverse ecological and social issues (Brown and MacLeod, 1996). Range economists in Texas and Australia face similar challenges and have pursued concentric paths in analyzing and participating in technology transfer. Three topics are developed: a portrayal of the parallelism in demographics and trends associated with range technology transfer in Texas and Australia, a discussion of the empirical and methodological issues raised in recent and current projects underway in Texas and Australia, and a brief synthesis identifying possible complementarities in these research agendas

    Killing-Yano tensors and some applications

    Full text link
    The role of Killing and Killing-Yano tensors for studying the geodesic motion of the particle and the superparticle in a curved background is reviewed. Additionally the Papadopoulos list [74] for Killing-Yano tensors in G structures is reproduced by studying the torsion types these structures admit. The Papadopoulos list deals with groups G appearing in the Berger classification, and we enlarge the list by considering additional G structures which are not of the Berger type. Possible applications of these results in the study of supersymmetric particle actions and in the AdS/CFT correspondence are outlined.Comment: 36 pages, no figure

    Paleoproductivity, ventilation, and organic carbon burial in the Santa Barbara Basin (ODP Site 893, off California) since the last glacial

    Get PDF
    Biogenic burial rates and coccolith assemblage data were generated for the past 16 ka at ODP Site 893 in the Santa Barbara Basin, off California, to determine if dysoxic events in the basin were related to changes in marine productivity. Coccolith abundance data show that changes in surface water conditions did indeed change in concert with oxygen levels at the sea floor. However, organic carbon burial rates varied independently, indicating that oxygenation of the water column is related mainly to intermediate water ventilation. A strong correlation of organic carbon burial rates with lithogenic, and to a lesser extent with carbonate and opal accumulation rates confirms recent conclusions that the export of organic carbon from the sea surface is largely controlled by the presence of ballast minerals

    Synthesis of bis(indolyl)methanes using silica gel as an efficient and recyclable surface

    Get PDF
    AbstractHere we describe a simple, clean, and efficient solvent-free protocol for the synthesis of bis(indolyl)methanes promoted by silica gel. The products were obtained in good to excellent yields through the reaction of indoles with cyclohexanone and a range of aldehydes. The silica gel was easily recovered and utilized for further reactions without loss of activity

    Impact of age norms and stereotypes on managers' hiring decisions of retirees

    Get PDF
    Purpose -Our study investigates the role of managers in the re-employment of early retirees and asks what the effect is of managers’ age norms and stereotypes on managers’ employment decisions. Design/methodology/approach- A combination of a factorial study and a survey was conducted. First, information on the age norms and stereotypes was collected. Secondly, profiles of hypothetical retired job applicants were presented to the employers, who were asked to make a specific hiring decision. The information collected during both studies was combined in the analysis and multilevel models were estimated. Findings -The results indicate that higher age norms result in a higher propensity to hire an early retiree. Stereotypes, by contrast, do not influence managers’ decisions. Early retirees’ chances for re-employment are also related to their own circumstances (physical appearance and relevant experience) and organisational forces, as they are hired when organisations face labour force shortages. Research limitation / implications – with the use of vignettes study we deal with hypothetical hiring situation. Originality value- Although the effect of age norms and age stereotypes has been often suggested, not much empirical evidence was presented to support this notion. Our study estimates the effect of age norms and stereotypes on hiring decision. key words: bridge employment; early retirees; age norms; age stereotypes; multilevel models.
    • …
    corecore