Material standards design for minimum zone fitting of freeform optics

International audienceIn most cases, ultra-high-precision coordinate measuring machines (CMMs) are used to measure manufactured parts especially in the presence of freeform surfaces. The obtained data should be then processed to determine a quality measure of the surface. The least value of peak-to-valley (PV) is the widely used quality measure since it conforms to the ISO Geometrical and Product Specification (GPS) standards. To determine the minimum value of PV, a number of fitting methods exist but minimum zone fitting is the most suitable since it directly minimizes the PV. In the measurement process, fitting algorithms are essential elements. For this reason, their quality must be assessed as well; this could be achieved using either softgauges or material artefacts. In this paper, a design of a reference thermo-invariant material standard for minimum zone fitting is suggested and manufactured. The artefact was then measured by a number of partners participating to the FreeFORM 15SIB-01 project so as a comparison could be made in the light of gathered measurements

Phylogeography and Population Structure of Glossina fuscipes fuscipes in Uganda: Implications for Control of Tsetse

Glossina fuscipes fuscipes is the most common species of tsetse in Uganda, where it transmits human sleeping sickness and nagana, a related disease of cattle. A consortium of African countries dedicated to controlling these diseases is poised to begin area wide control of tsetse, but a critical question remains: What is the most appropriate geographical scale for these activities? To address this question, we used population genetics to determine the extent of linkage between populations of tsetse confined to discrete patches of riverine habitat. Our results suggest that Uganda was colonized by two distinct lineages of G. f. fuscipes, which now co-occur only in a narrow band across central Uganda. Evidence for interbreeding at the zone of contact and movement of genes from the south to the north suggest that this historical genetic structure may dissolve in the future. At smaller scales, we have demonstrated that exchange of genes among neighboring populations via dispersal is at equilibrium with the differentiating force of genetic drift. Our results highlight the need for investment in vector control programs that account for the linkage observed among tsetse populations. Given its genetic isolation and its location at the far edge of G. fuscipes' range, the Lake Victoria region appears to be an appropriate target for area wide control

The origin of overpressure in 'old' sedimentary basins: an example from the Cooper Basin, Australia

The definitive version is available at www.blackwell-synergy.comOverpressure in 'old' sedimentary basins that have not undergone rapid, recent sedimentation cannot be easily explained using traditional burial-driven mechanisms. The last significant burial event in the Cooper Basin, Australia, was the Late Cretaceous deposition of the Winton Formation (98.5-90 Ma). Maximum temperature in the basin was attained during the Late Cretaceous, with cooling beginning prior to 75 Ma. Hence, overpressure related to rapid burial or palaeomaximum temperatures (e.g. hydrocarbon generation) must have developed prior to 75 Ma. Retaining overpressure for 75 Ma in 'old' basins such as the Cooper Basin requires extremely low seal permeabilities. An alternative explanation is that overpressure in the Cooper Basin has been generated because of an increase in mean stress associated with an increase in horizontal compressive stress since Late Cretaceous times. Structural observations and contemporary stress data indicate that there has been an increase in mean stress of approximately 50 MPa between Late Cretaceous times to that presently measured at 3780 m. The largest measured overpressure in the Cooper Basin is 14.5 MPa at 3780 m in the Kirby 1 well. Hence, disequilibrium compaction driven by increasing mean stress can explain the magnitude of the observed overpressure in the Cooper Basin. Increases in mean stress (tectonic loading) may be a feasible mechanism for overpressure generation in other 'old' basins that have undergone a recent increase in horizontal stress (e.g. Anadarko Basin).P. Van Ruth, R. Hillis, P. Tingate and R. Swarbric

Material standards design for minimum zone fitting of freeform optics

International audienceIn most cases, ultra-high-precision coordinate measuring machines (CMMs) are used to measure manufactured parts especially in the presence of freeform surfaces. The obtained data should be then processed to determine a quality measure of the surface. The least value of peak-to-valley (PV) is the widely used quality measure since it conforms to the ISO Geometrical and Product Specification (GPS) standards. To determine the minimum value of PV, a number of fitting methods exist but minimum zone fitting is the most suitable since it directly minimizes the PV. In the measurement process, fitting algorithms are essential elements. For this reason, their quality must be assessed as well; this could be achieved using either softgauges or material artefacts. In this paper, a design of a reference thermo-invariant material standard for minimum zone fitting is suggested and manufactured. The artefact was then measured by a number of partners participating to the FreeFORM 15SIB-01 project so as a comparison could be made in the light of gathered measurements

Unusual Phenotypic Features in a Patient with a Novel Splice Mutation in the GHRHR Gene

Isolated growth hormone deficiency (IGHD) may be of genetic origin. One of the few genes involved in that condition encodes the growth hormone releasing hormone receptor (GHRHR) that, through its ligand (GHRH), plays a pivotal role in the GH synthesis and secretion by the pituitary. Our objective is to describe the phenotype of two siblings born to a consanguineous union presenting with short stature (IGHD) and Magnetic Resonance Imaging (MRI) abnormalities, and to identify the molecular basis of this condition. Our main outcome measures were clinical and endocrinological investigations, MRI of the pituitary region, study of the GHRHR gene sequence and transcripts. In both patients, the severe growth retardation (−5SD) was combined with anterior pituitary hypoplasia. In addition to these classical phenotypic features for IGHD, one of the patients had a Chiari I malformation, an arachnoid cyst, and a dysmorphic anterior pituitary. A homozygous sequence variation in the consensus donor splice site of intron 1 (IVS1 + 2T > G) of the GHRHR gene was identified in both patients. Using in vitro transcription assay, we showed that this mutation results in abnormal splicing of GHRHR transcripts. In this report, which broadens the phenotype associated with GHRHR defects, we discuss the possible role of the GHRHR in the proper development of extrapituitary structures, through a mechanism that could be direct or secondary to severe GH deficiency