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BackgroundRecent genome-wide association studies of colorectal cancer (CRC) have identified common single-nucleotide polymorphisms (SNPs) mapping to 10 independent loci that confer modest increased risk. These studies have been conducted in European populations and it is unclear whether these observations generalise to populations with different ethnicities and rates of CRC.MethodsAn association study was performed on 892 CRC cases and 890 controls recruited from the Hong Kong Chinese population, genotyping 32 SNPs, which were either associated with CRC in previous studies or are in close proximity to previously reported risk SNPs.ResultsTwelve of the SNPs showed evidence of an association. The strongest associations were provided by rs10795668 on 10p14, rs4779584 on 15q14 and rs12953717 on 18q21.2. There was significant linear association between CRC risk and the number of independent risk variants possessed by an individual (P=2.29 × 10(-5)).ConclusionThese results indicate that some previously reported SNP associations also impact on CRC risk in the Chinese population. Possible reasons for failure of replication for some loci include inadequate study power, differences in allele frequency, linkage disequilibrium structure or effect size between populations. Our results suggest that many associations for CRC are likely to generalise across populations.

This note introduces an interesting random walk on a straight path with cards of random numbers. The method of recurrent relations is used to obtain the convergent probability of the random walk with different initial positions.

We report the epitaxial integration of defect-induced room temperature ferromagnetic insulators, Cr2O3 and MgO, with topological insulators Bi2Se3 on c-sapphire substrate by pulsed laser deposition. The structural, magnetic, and magnetotransport properties of ~15 nm Bi2Se3 thin films are investigated on each template. The lattice misfits of Cr2O3/Bi2Se3 and MgO/Bi2Se3 are ~16% and ~39%, respectively, where the critical thickness for pseudomorphic growth is less than one monolayer. The insulating behavior is more pronounced due to the additional scattering of the surface states of the Bi2Se3 layer by interfacing with MgO and Cr2O3. The weak antilocalization effect from the surface states is clearly suppressed, accounting for the presence of magnetic bottom layers. This work demonstrates an effective way to study the emergence of a ferromagnetic phase in topological insulators by the magnetic proximity effect in Bi2Se3, a step toward unveiling their exotic properties. [ABSTRACT FROM AUTHOR]

We report a systematic study of the structural, physical, and chemical properties of epitaxial thin films of emerging dilute magnetic semiconductor (DMS) Sr3SnO (SSO) integrated with Si (100) prepared by various post-growth annealing treatments. The transport properties of these films are primarily governed by oxygen vacancies and the results are explained with the variable-range hopping model. The increased oxygen vacancy concentration generated by post-growth vacuum annealing results in a shorter hopping distance and reduced hopping energy and Coulomb gap, leading to lower resistivity; oxygen annealing shows the opposite effects. The work function ranges from 4.54 to 4.02eV and shows a negative linear relationship with oxygen vacancy concentration, accompanied by a 0.42 eV shift in the surface Fermi level. The transport and ultraviolet photoelectron spectroscopy probes agree quantitatively on measurement of the resistivity and surface electronic structure. The results provide a direct and consistent explanation that the property changes in the bulk and at the surface are primarily attributed to oxygen vacancies, which are believed to be the carriers in the SSO thin films. The ability to manipulate the work function and oxygen vacancy concentration in epitaxial DMS SSO thin films offers great potential for the development of spintronic devices. [ABSTRACT FROM AUTHOR]