5,330 research outputs found
Introduction to the Apollo collections: Part 2: Lunar breccias
Basic petrographic, chemical and age data for a representative suite of lunar breccias are presented for students and potential lunar sample investigators. Emphasis is on sample description and data presentation. Samples are listed, together with a classification scheme based on matrix texture and mineralogy and the nature and abundance of glass present both in the matrix and as clasts. A calculus of the classification scheme, describes the characteristic features of each of the breccia groups. The cratering process which describes the sequence of events immediately following an impact event is discussed, especially the thermal and material transport processes affecting the two major components of lunar breccias (clastic debris and fused material)
Dydrogesterone and norethisterone regulate expression of lipoprotein lipase and hormones-sensitive lipase in human subcutaneous abdominal adipocytes
Aim: In premenopausal women, hyper-androgenicity is associated with central obesity and an increased cardiovascular risk. We investigated the effects of dydrogesterone (DYD)(a non-androgenic progestogen) and norethisterone (NET)(an androgenic progestogen) on lipoprotein lipase (LPL), hormone-sensitive lipase (HSL) and glycerol release in adipocytes isolated from subcutaneous abdominal adipose tissue. Methods: Adipose tissue was obtained from 12 non-diabetic women, mean age 51 years (range 37-78) and mean BMI 25.4kg/m2 (range 20.3-26.4). Adipocytes were treated with increasing doses of DYD and NET for 48 hours prior to protein extraction. Effects on lipogenesis and lipolysis were assessed using western blotting to determine the expression of key enzymes, LPL (56kDa) and HSL (84kDa) respectively. Measurement of glycerol release into the medium provided an assessment of lipolytic activity. Results: Expression of LPL was increased by DYD and NET (mean protein expression relative to control ± SEM); with greatest effect at 10-8M for DYD: 2.32±0.51(p0.05). Conclusions: DYD and NET significantly increased LPL expression relative to control whilst significantly reducing HSL expression. At the concentrations studied, similar effects were observed with the androgenic NET and the non-androgenic DYD despite differing effects on the lipid profile when taken
in combination with estrogen. Further work in this area may improve knowledge about the effects of different progestogens on body fat distribution and enable progestogen use to be tailored to the individual to achieve maximal benefits
Novel Josephson effects between multi-gap and single-gap superconductors
Multi-gap superconductors can exhibit qualitatively new phenomena due to
existence of multiple order parameters. Repulsive electronic interactions may
give rise to a phase difference of between the phases of the order
parameters. Collective modes due to the oscillation of the relative phases of
these order parameters are also possible. Here we show that both these
phenomena are observable in Josephson junctions between a single-gap and a
multi-gap superconductor. In particular, a non-monotonic temperature dependence
of the Josephson current through the junction reveals the existence of the
phase differences in the multi-gap superconductor. This mechanism may be
relevant for understanding several experiments on the Josephson junctions with
unconventional superconductors. We also discuss how the presence of the
collective mode resonantly enhances the DC Josephson current when the voltage
across the junction matches the mode frequency. We suggest that our results may
apply to MgB, 2H-NbSe, spin ladder and bilayer cuprates.Comment: 4 pages, 2 figure
Waste Corn as a Source of Inoculum of Aspergillus Flavus, the Cause of Aflatoxin
Aspergillus Flavus occurs worldwide in diverse habitats on a variety of plant and animal substrates. In the United States, contamination of susceptible crops particularly maize, peanuts, cottonseed, and tree nuts has become a major health concern because of the development of the carcinogen, aflatoxin. Extensive research into all aspects of the biology of A. flavus over the past twenty years still has left many unanswered but very basic questions about the ecology of this important organism
ADAMTS13 mutations identified in familial TTP patients result in loss of VWF‐cleaving protease activity
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106109/1/jth03964.pd
Introducing a comprehensive data reduction algorithm for high-precision U-Th geochronology with isotope dilution MC-ICP-MS
Multi collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is being increasingly utilized for
U-Th geochronology of carbonate deposits with comparable
precision to thermal ionization mass spectrometry (TIMS) [1,
2]. While attention has been paid to propagation of
uncertainties for U-Th-Pb analysis by TIMS and the isochron
technique [3,4], a comprehensive data processing scheme is
lacking for MC-ICP-MS. To address this need, we have
developed an algorithm in Mathematica application to allow
for step-by-step monitoring of the data reduction process. The program is flexible and affords the user easy control over input variables. Adjustments for background and spike isotope contributions, abundance sensitivity and instrumental mass bias are implemented through the code, followed by age calculation and propagation of uncertainties with Monte Carlo simulation. A rigorous standard bracketing procedure was adopted using Uranium (CRM-112A) and Th (IRMM-035) standard solutions, doped with IRMM-3636a ^(233)U/^(236)U “double-spike”, to account for deviations of isotope ratios from certificate values and improve accuracy. Following a single U/TEVA extraction chromatography step to separate U from Th, ten replicate ages from a speleothem in Cathedral Cave (CC), Utah showed excellent agreement (R^2 = 0.999) with results previously measured at the University of Minnesota by single collection ICP-MS [5]. The external reproducibility of our analytical technique was evaluated by analyzing six aliquots of an in-house standard, prepared by homogenizing a piece of the CC speleothem, which returned a mean age of 21468±120 y (2SD). A limited amount of the standard powder is available upon request for interlaboratory calibration. We have successfully dated 36 samples from caves in the Bahamas, the Dominican Republic and Iran
- …