In response to reported schizophrenia linkage findings on chromosomes 3, 6 and 8, fourteen research groups genotyped 14 microsatellite markers in an unbiased, collaborative (New) sample of 403–567 ...informative pedigrees per marker, and in the Original sample which produced each finding (the Johns Hopkins University sample of 46–52 informative pedigrees for chromosomes 3 and 8, and the Medical College of Virginia sample of 156–191 informative pedigrees for chromosome 6). Primary planned analyses (New sample) were two‐point heterogeneity lod score (lod2) tests (dominant and recessive affected‐only models), and multipoint affected sibling pair (ASP) analysis, with a narrow diagnostic model (DSM‐IIIR schizophrenia and schizoaffective disorders). Regions with positive results were also analyzed in the Original and Combined samples. There was no evidence for linkage on chromosome 3. For chromosome 6, ASP maximum lod scores (MLS) were 2.19 (New sample, nominal p = .001) and 2.68 (Combined sample, p=.0004). For chromosome 8, maximum lod2 scores (tests of linkage with heterogeneity) were 2.22 (New sample, p=.0014) and 3.06 (Combined sample, p = .00018). Results are interpreted as inconclusive but suggestive of linkage in the latter two regions. We discuss possible reasons for failing to achieve a conclusive result in this large sample. Design issues and limitations of this type of collaborative study are discussed, and it is concluded that multicenter follow‐up linkage studies of complex disorders can help to direct research efforts toward promising regions.
Astrophys.J.525:554-582,1999 We have simulated the formation of an X-ray cluster in a cold dark matter
universe using 12 different codes. The codes span the range of numerical
techniques and ...implementations currently in use, including SPH and grid methods
with fixed, deformable or multilevel meshes. The goal of this comparison is to
assess the reliability of cosmological gas dynamical simulations of clusters in
the simplest astrophysically relevant case, that in which the gas is assumed to
be non-radiative. We compare images of the cluster at different epochs, global
properties such as mass, temperature and X-ray luminosity, and radial profiles
of various dynamical and thermodynamical quantities. On the whole, the
agreement among the various simulations is gratifying although a number of
discrepancies exist. Agreement is best for properties of the dark matter and
worst for the total X-ray luminosity. Even in this case, simulations that
adequately resolve the core radius of the gas distribution predict total X-ray
luminosities that agree to within a factor of two. Other quantities are
reproduced to much higher accuracy. For example, the temperature and gas mass
fraction within the virial radius agree to about 10%, and the ratio of specific
kinetic to thermal energies of the gas agree to about 5%. Various factors
contribute to the spread in calculated cluster properties, including
differences in the internal timing of the simulations. Based on the overall
consistency of results, we discuss a number of general properties of the
cluster we have modelled.
We have simulated the formation of an X-ray cluster in a cold dark matter universe using 12 different codes. The codes span the range of numerical techniques and implementations currently in use, ...including SPH and grid methods with fixed, deformable or multilevel meshes. The goal of this comparison is to assess the reliability of cosmological gas dynamical simulations of clusters in the simplest astrophysically relevant case, that in which the gas is assumed to be non-radiative. We compare images of the cluster at different epochs, global properties such as mass, temperature and X-ray luminosity, and radial profiles of various dynamical and thermodynamical quantities. On the whole, the agreement among the various simulations is gratifying although a number of discrepancies exist. Agreement is best for properties of the dark matter and worst for the total X-ray luminosity. Even in this case, simulations that adequately resolve the core radius of the gas distribution predict total X-ray luminosities that agree to within a factor of two. Other quantities are reproduced to much higher accuracy. For example, the temperature and gas mass fraction within the virial radius agree to about 10%, and the ratio of specific kinetic to thermal energies of the gas agree to about 5%. Various factors contribute to the spread in calculated cluster properties, including differences in the internal timing of the simulations. Based on the overall consistency of results, we discuss a number of general properties of the cluster we have modelled.
