OBJECTIVES To examine the frequency of surrogate decisions for in-hospital do-not-resuscitate (DNR) orders and the timing of DNR order entry for surrogate decisions. DESIGN Retrospective cohort study. SETTING Large, urban, public hospital. PARTICIPANTS Hospitalized adults aged 65 and older over a 3-year period (1/1/2004-12/31/2006) with a DNR order during their hospital stay. MEASUREMEN...

Before we apply nonlinear techniques, e.g. those inspired by chaos theory, to dynamical phenomena occurring in nature, it is necessary to first ask if the use of such advanced techniques is justified by the data. While many processes in nature seem very unlikely a priori to be linear, the possible nonlinear nature might not be evident in specific aspects of their dynamics. The method of surroga...

Surrogate-based optimization (Queipo et al. 2005, Simpson et al. 2008) represents a class of optimization methodologies that make use of surrogate modeling techniques to quickly find the local or global optima. It provides us a novel optimization framework in which the conventional optimization algorithms, e.g. gradient-based or evolutionary algorithms are used for sub-optimization(s). Surrogat...

A surrogate endpoint is defined as a biomarker intended to substitute for a clinical endpoint, such as an incidence, or mortality. The evidence supporting the linkage of a biomarker to accurately substitute for a clinical endpoint may be derived from epidemiologic studies, clinical trials, in vitro analysis, animal models, and simulated biologic systems. Analytical epidemiological studies of th...

A holy grail of conservation is to find simple but reliable measures of environmental change to guide management. For example, particular species or particular habitat attributes are often used as proxies for the abundance or diversity of a subset of other taxa. However, the efficacy of such kinds of species-based surrogates and habitat-based surrogates is rarely assessed, nor are different kin...

progression [2]. In addition, the time gain is very large in cancers for which the response rate is used as a surrogate end point such as hematological malignancy [3]. Second, we are not discussing a surrogate end point for less serious disease like cardiovascular disease [4], but are discussing a surrogate end point supporting clinical trials of innovative new drugs of high unmet medical need ...

This work presents Lagrangean/surrogate relaxation to the problem of maximum pro®t assignment of n tasks to m agents (n > m), such that each task is assigned to only one agent subject to capacity constraints on the agents. The Lagrangean/surrogate relaxation combines usual Lagrangean and surrogate relaxations relaxing ®rst a set of constraints in the surrogate way. Then, the Lagrangean relaxati...

Surrogate endpoints offer the hope of smaller or shorter cancer trials. It is, however, important to realize they come at the cost of an unverifiable extrapolation that could lead to misleading conclusions. With cancer prevention, the focus is on hypothesis testing in small surrogate endpoint trials before deciding whether to proceed to a large prevention trial. However, it is not generally app...