Two-phase analysis in consensus genetic mapping.

Numerous mapping projects conducted on different species have generated an abundance of mapping data. Consequently, many multilocus maps have been constructed using diverse mapping populations and marker sets for the same organism. The quality of maps varies broadly among populations, marker sets, and software used, necessitating efforts to integrate the mapping information and generate consensus maps. The problem of consensus genetic mapping (MCGM) is by far more challenging compared with genetic mapping based on a single dataset, which by itself is also cumbersome. The additional complications introduced by consensus analysis include inter-population differences in recombination rate and exchange distribution along chromosomes; variations in dominance of the employed markers; and use of different subsets of markers in different labs. Hence, it is necessary to handle arbitrary patterns of shared sets of markers and different level of mapping data quality. In this article, we introduce a two-phase approach for solving MCGM. In phase 1, for each dataset, multilocus ordering is performed combined with iterative jackknife resampling to evaluate the stability of marker orders. In this phase, the ordering problem is reduced to the well-known traveling salesperson problem (TSP). Namely, for each dataset, we look for order that gives minimum sum of recombination distances between adjacent markers. In phase 2, the optimal consensus order of shared markers is selected from the set of allowed orders and gives the minimal sum of total lengths of nonconflicting maps of the chromosome. This criterion may be used in different modifications to take into account the variation in quality of the original data (population size, marker quality, etc.). In the foregoing formulation, consensus mapping is considered as a specific version of TSP that can be referred to as "synchronized TSP." The conflicts detected after phase 1 are resolved using either a heuristic algorithm over the entire chromosome or an exact/heuristic algorithm applied subsequently to the revealed small non-overlapping regions with conflicts separated by non-conflicting regions. The proposed approach was tested on a wide range of simulated data and real datasets from maize.

Home-based occupational therapy: then and now.

Although there are differences in the scope and practice of occupational therapists working with homebound clients in 1925 and 1991, the underlying philosophy remains the same (i.e., the treatment or intervention involves not only the patient, but also his or her environment). Occupational therapists working in an outpatient clinic or home setting should perceive their treatment as curative measures through the use of occupation. Such treatment exercises muscles as well as the mind.

Home health care and the elderly in the 1980s.

Because the cost of institutional care for long-term patients has risen, home health has become a more visible and viable alternative to the growing elderly population. This article discusses problems found in the rapid expansion of home health services and presents two alternative health care delivery systems that address these problems: the Medicaid Waiver and the Social/Health Maintenance Organization.