Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study

The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10−8) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10−8). The top IBC association for SBP was rs2012318 (P= 6.4 × 10−6) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10−6) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexit

Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study.

The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10(-8)) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10(-8)). The top IBC association for SBP was rs2012318 (P= 6.4 × 10(-6)) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10(-6)) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexity

Hypervelocity impact on brittle materials of semi-infinite thickness: Fracture morphology related to projectile diameter

Hypervelocity impact on brittle materials produces features not observed on ductile targets. Low fracture toughness and high yield strength produce a range of fracture morphologies including cracking, spallation and shatter. For sub-mm diameter projectiles, impact features are characterised by petaloid spallation separated by radial cracks. The conchoidal or spallation diameter is a parameter in current cratering equations. An alternative method for interpreting hypervelocity impacts on glass targets of semi-infinite thickness is tested against impact data produced using the Light Gas Gun (LGG) facility at the University of Rent at Canterbury (UKC), U.K. Spherical projectiles of glass and other materials with diameters 30-300 mu m were fired at similar to 5 km s(-1) at a glass target of semi-infinite thickness. The data is used to test a power law relationship between projectile diameter and crack length. The results of this work are compared with published cratering/spallation equations for brittle materials. (C) 1997 COSPAR

Laboratory Investigations of the Temperature Dependence of Hypervelocity Impact Cratering in Ice

Laboratory investigations by hypervelocity impact cratering in water ices are usually carried out at temperatures of approximate 250-265 K. However, icy surfaces in the Solar System are typically at lower temperatures. Accordingly a study of the temperature dependence of cratering in water ice has been carried out using a two-stage light gas gun firing mm-sized projectile at 5 - 6 km s(-1). The temperature of the water ice targets has been varied in the range 152-253 K. The variation in depth, diameter and volume of the resulting craters is presented as a function of temperature. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved

Scaling of hypervelocity impact craters in ice with impact angle

Hypervelocity oblique impacts using spherical 1 mm diameter aluminum projectiles at velocities of (5.2 +/- 0.2) km s(-1) were incident at angles ranging from normal (0degrees to the vertical) to grazing incidence (80) onto thick polycrystalline H2O ice targets at 253 K. Data were obtained to distinguish changes in crater size and shape. The resultant craters had a deep central pit surrounded by a shallower terrace. Results on crater size showed that volume and crater depth had varying levels of dependence on obliquity for the full angular range, and terrace depth had a dependence only at angles > 45degrees. Length and width measurements held a strong dependence on obliquity only at angles > 50degrees from the normal. These results for ice show that it is hard to determine angle of impact from crater morphology. Although crater depth and volume do change with angle, it would be hard to separate this effect from the influence of an impact of a projectile of different speed, density, etc., which might also affect crater depth or crater depth/diameter ratios. Only at extreme angles > 70degrees do real differences in shape emerge for ice

Velocity scaling of impact craters in water ice over the range 1 to 7.3 km s(-1)

The impact cratering behavior of polycrystalline ice at a temperature of 259 3 K has been investigated by 16 impacts with 1-mm aluminum 2017 alloy spheres (density 2790 kg m(-3)) over the velocity range 1 to 7.3 km s(-1) using a two-stage light-gas gun. Crater cross-sectional profiles and diameter, depth, and volume data are presented. It is found that there is no significant difference in power-law energy exponents for scaling of crater diameter and volume between these data and previous low-velocity (<1 km s(-1)) ice impact data. Dimensionless pi group scaling was also found to scale the data in a way which can be readily combined with earlier lower velocity, data and data at a lower ice temperature. (C) 2002 Elsevier Science (USA)

Laboratory Investigations of Hypervelocity Impact Cratering in Ice

Hypervelocity impact experiments on water ice targets have been performed using a two stage light gas gun. The resulting craters were measured to obtain the crater depth and diameter. From the data set for 23 impact craters, damage equations have been obtained which give the crater depth (diameter) in terms of the dependence on impact velocity, projectile diameter and projectile density. The resulting damage equations are compared to those for another brittle material, glass. Scaling of the excavated crater volume with energy is shown to obey a simple power law over 10 orders of magnitude in energy (10(-7) to 10(3) J)

Exobiology: Laboratory tests of the impact related aspects of Panspermia

The idea that life began elsewhere and then naturally migrated to the Earth is known as Panspermia. One such possibility is that life is carried on objects (meteorites, comets and dust) that arrive at the Earth. The life (bacteria) is then presumed to survive the sudden deceleration and impact, and then subsequently develop here on Earth. This step, the survivability of bacteria during the deceleration typical of an object arriving at Earth from space, is studied in this paper. To this end a two-stage light gas gun was used to fire projectiles coated with bacteria into a variety of targets at impact speeds of 3.8 to 4.9 km s(-1). Targets used were rock, glass, metal and aerogel (density 100 kg m(-3)). Various techniques were used to search for bacteria that had transferred to the target material during the impact. These included taking cultures from the target crater and ejecta, and use of fluorescent dyes to mark sites of live bacteria. So far only one sample has shown a signal for bacteria surviving an impact. This was for bacteria cultured from the ejecta spalled from a rock surface during an impact. However, this result needs to be repeated before any firm claims can be made for bacteria surviving a hypervelocity impact event

Using solar cells as microparticle detectors in low earth orbit

On retrieval from Low Earth Orbit (LEG), the solar arrays from the European Retrievable Carrier(EuReCa) and one solar array wing of the Hubble Space Telescope (HST) were inspected for micrometeoroid and space debris impact damage. 703 and 814 impact sites respectively were analysed in detail. Interpretation of particle parameters from this large data set can yield a useful measurement of the micrometeoroid and debris flux in LEG. Due to similar orbital parameters, this then provides a flux measurement complimentary to those measured by the Timeband Capture Cell Experiment (TiCCE) of the EuReCa spacecraft and detectors and exposed surfaces on the Long Duration Exposure Facility (LDEF). To allow comparison of data from the space retrieved solar cells to previous data, solar cell material, glass and aluminium targets were impacted for inter-calibration using the University of Kent's Light Gas Gun (LGG). An average of 20 impact sites on each target material per shot were measured. It was decided to consider only non-perforations of the 150 micron thick CMX cover glass, common to both EuReCa and HST solar cells. Trends in crater morphology of the laboratory impacts are discussed and compared to those from space impacts. The effects of impact angle and crater scaling with particle size are investigated and a conversion from appropriate solar cell crater parameters to the ballistic limit in aluminium is presented

Micropartcle Impact Flux on the Timeband Capture Cell Experiment of the Eureca Spacecraft

Measurements of hypervelocity impact fluxes (in both thick and thin targets) detected by the University of Kent at Canterbury's Timeband Capture Cell Experiment (TiCCE) (flown on ESA's Eureca spacecraft) are presented. The foil perforations are used to derive the ballistic limit values, or the maximum thickness of Al perforated, for the impacting particles. This data is then combined with the thick target data to derive a unified ballistic limit flux. A significant enhancement in the observed large particle flux compared with LDEF is found, possibly due to the pointing history of Eureca compared to the Earth's orbital direction. Comparisons are also made to predictions from ESABASE modelling. Preliminary results of a study of perforation morphology are also presented, providing insight into particle shape, density and directionality