MHF1–2/CENP-S-X performs distinct roles in centromere metabolism and genetic recombination

Peer reviewedPublisher PD

Toward an Instrumented Strength Microprobe – Origins of the Oliver-Pharr Method and Continued Advancements in Nanoindentation: Part 1

Sub-micron instrumented indentation testing and standardized nanoindentation testing systems have become commonplace within the materials engineering community. Though commonly utilized for mechanical characterization, general appreciation and understanding of the governing theory, formulations and best practices underpinning modern nanoindentation systems appears to remain relatively elusive to the general materials science and engineering community as well as nanoindentation practitioners using such systems for mechanical assessment. Accordingly, the present chapter details how nanoindentation methods emerged and how the Oliver-Pharr method of nanoindentation testing and analysis was constructed and refined to yield theoretically consistent and readily implementable attributes for probing small-scale mechanical properties via microscopy free indentation testing

Toward an Instrumented Strength Microprobe: Origins of the Oliver-Pharr Method and Continued Advancements in Nanoindentation—Part 2

Numerable advancements have afforded many benefits to nanoindenter system operators since the late 20th century, such as automation of measurements, enhanced load and displacement resolutions, and indentation with in-situ capabilities. Accordingly, the present chapter details how the Oliver-Pharr method of nanoindentation testing and analysis was adopted and relied upon as a framework that brought about widespread advancements in instrumented indentation testing. The present chapter introduces an emergent and theoretically consistent approach to assessing true stress–strain curves at a micromechanical scale using a flat-punch nanoindenter tip geometry and reliance upon Hollomon power-law plasticity and constitutive parameter fitting. Finally, a novel flat-punch nanoindentation testing method and approach to plasticity parameter analysis for metallic materials using nanoindentation systems can be implemented, bringing about an instrumented strength microprobe – a long sought-after tool

Inherited polyglutamine spinocerebellar ataxias in South Africa

Objective. To determine the frequency and distribution of polyglutamine spinocerebellar ataxias (SCAs) from referrals over a 24-year period to the National Health Laboratory Service (NHLS) in South Africa (SA). Methods. Paper-based clinical reports in the University of Cape Town laboratory and the NHLS electronic patient record database spanning a 24-year period were mined for information regarding the molecular diagnosis, ethnicity and CAG repeat length for individuals referred for molecular genetic testing for the polyglutamine SCAs. Results. SCA1 and 7 are the most frequent types of polyglutamine SCA in the SA patient population, followed by SCA2, 3 and 6. SCA1 is the most common type in the coloured, white and Indian populations, whereas the majority of indigenous black African patients are affected with SCA7 and 2. Of individuals tested, 22% were found to be positive for one of the polyglutamine SCAs. Conclusion. Although trends in the frequency and distribution of the polyglutamine SCAs in SA have not changed significantly since our previous study in 2003, they differ remarkably from those reported elsewhere, and reflect the unique genetic and demographic background of SA. The provision of accurate and complete patient information and family history is crucial to the diagnostic process, to enable comprehensive epidemiological studies and assist in developing therapeutic and patient management strategies

Spinocerebellar Ataxia Type 23: A Genetic Update

The spinocerebellar ataxia type 23 locus was identified in 2004 based on linkage analysis in a large, two-generation Dutch family. The age of onset ranged 43–56 years and the phenotype was characterized by a slowly progressive, isolated ataxia. Neuropathological examination revealed neuronal loss in the Purkinje cell layer, dentate nuclei, and inferior olives. Ubiquitin-positive intranuclear inclusions were found in nigral neurons, but were considered to be Marinesco bodies. The disease locus on chromosome 20p13-12.3 was found to span a region of approximately 6 Mb of genomic DNA, containing 97 known or predicted genes. To date, no other families have been described that also map to this SCA locus. Direct sequencing of the coding regions of 21 prioritized candidate genes did not reveal any disease-causing mutation. Apparently, the SCA23 gene is a disease gene with a different function than the genes that have been associated with other known SCA types. Work to elucidate the chromosomal organization of the SCA23 locus will eventually discover the responsible disease gene

Slx8 removes Pli1-dependent protein-SUMO conjugates including SUMOylated Topoisomerase I to promote genome stability

Peer reviewedPublisher PD

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE