2,050 research outputs found
Insulin clearance and the incidence of type 2 diabetes in Hispanics and African Americans: the IRAS Family Study.
ObjectiveWe aimed to identify factors that are independently associated with the metabolic clearance rate of insulin (MCRI) and to examine the association of MCRI with incident type 2 diabetes in nondiabetic Hispanics and African Americans.Research design and methodsWe investigated 1,116 participants in the Insulin Resistance Atherosclerosis Study (IRAS) Family Study with baseline examinations from 2000 to 2002 and follow-up examinations from 2005 to 2006. Insulin sensitivity (S(I)), acute insulin response (AIR), and MCRI were determined at baseline from frequently sampled intravenous glucose tolerance tests. MCRI was calculated as the ratio of the insulin dose over the incremental area under the curve of insulin. Incident diabetes was defined as fasting glucose â„126 mg/dL or antidiabetic medication use by self-report.ResultsWe observed that S(I) and HDL cholesterol were independent positive correlates of MCRI, whereas fasting insulin, fasting glucose, subcutaneous adipose tissue, visceral adipose tissue, and AIR were independent negative correlates (all P < 0.05) at baseline. After 5 years of follow-up, 71 (6.4%) participants developed type 2 diabetes. Lower MCRI was associated with a higher risk of incident diabetes after adjusting for demographics, lifestyle factors, HDL cholesterol, indexes of obesity and adiposity, and insulin secretion (odds ratio 2.01 [95% CI 1.30-3.10], P = 0.0064, per one-SD decrease in loge-transformed MCRI).ConclusionsOur data showed that lower MCRI predicts the incidence of type 2 diabetes
WHAM Observations of H-alpha Emission from High Velocity Clouds in the M, A, and C Complexes
The first observations of the recently completed Wisconsin H-Alpha Mapper
(WHAM) facility include a study of emission lines from high velocity clouds in
the M, A, and C complexes, with most of the observations on the M I cloud. We
present results including clear detections of H-alpha emission from all three
complexes with intensities ranging from 0.06 R to 0.20 R. In every observed
direction where there is significant high velocity H I gas seen in the 21 cm
line we have found associated ionized hydrogen emitting the H-alpha line. The
velocities of the H-alpha and 21 cm emission are well correlated in every case
except one, but the intensities are not correlated. There is some evidence that
the ionized gas producing the H-alpha emission envelopes the 21 cm emitting
neutral gas but the H-alpha "halo", if present, is not large. If the H-alpha
emission arises from the photoionization of the H I clouds, then the implied
Lyman continuum flux F_{LC} at the location of the clouds ranges from 1.3 to
4.2 x 10^5 photons cm^{-2} s^{-1}. If, on the other hand, the ionization is due
to a shock arising from the collision of the high-velocity gas with an ambient
medium in the halo, then the density of the pre-shocked gas can be constrained.
We have also detected the [S II] 6716 angstrom line from the M I cloud and have
evidence that the [S II] to H-alpha ratio varies with location on the cloud.Comment: 32 pages, 18 figures, to appear in ApJ (Sept. 10, 1998
Combination of methylated-DNA precipitation and methylation-sensitive restriction enzymes (COMPARE-MS) for the rapid, sensitive and quantitative detection of DNA methylation
Hypermethylation of CpG island (CGI) sequences is a nearly universal somatic genome alteration in cancer. Rapid and sensitive detection of DNA hypermethylation would aid in cancer diagnosis and risk stratification. We present a novel technique, called COMPARE-MS, that can rapidly and quantitatively detect CGI hypermethylation with high sensitivity and specificity in hundreds of samples simultaneously. To quantitate CGI hypermethylation, COMPARE-MS uses real-time PCR of DNA that was first digested by methylation-sensitive restriction enzymes and then precipitated by methyl-binding domain polypeptides immobilized on a magnetic solid matrix. We show that COMPARE-MS could detect five genome equivalents of methylated CGIs in a 1000- to 10â000-fold excess of unmethylated DNA. COMPARE-MS was used to rapidly quantitate hypermethylation at multiple CGIs in >155 prostate tissues, including benign and malignant prostate specimens, and prostate cell lines. This analysis showed that GSTP1, MDR1 and PTGS2 CGI hypermethylation as determined by COMPARE-MS could differentiate between malignant and benign prostate with sensitivities >95% and specificities approaching 100%. This novel technology could significantly improve our ability to detect CGI hypermethylation
Optical interconnect with densely integrated plasmonic modulator and germanium photodetector arrays
We demonstrate the first chip-to-chip interconnect utilizing a densely integrated plasmonic Mach-Zehnder modulator array operating at 3 x 10 Gbit/s. A multicore fiber provides a compact optical interface, while the receiver consists of germanium photodetectors
A Map of the Ionized Component of the Intermediate Velocity Cloud Complex K
The Wisconsin H-Alpha Mapper (WHAM) Northern Sky Survey is revealing that
many intermediate-velocity (|v_LSR| <= 100 km/s) neutral clouds and complexes
have an associated ionized component. We present the first map of the H-Alpha
emission from an intermediate- or high-velocity structure: Complex K. This
large, high-latitude feature stretches from l = 10 to 70 degrees, b = +30 to
+70 degrees and peaks in velocity over v_LSR ~ -60 to -80 km/s. The neutral and
ionized gas generally trace each other quite well in the complex, but the
detailed structure is not identical. In particular, the H-Alpha emission peaks
in brightness at slightly higher Galactic longitudes than corresponding 21 cm
features. The ionized gas has a peak H-Alpha intensity of 0.5 Rayleighs,
corresponding to an emission measure of 1.1 cm^-6 pc. Structures in the complex
are traced by WHAM down to about 0.1 Rayleighs (0.2 cm^-6 pc). Typical line
widths of the H-Alpha emission are ~ 30 km/s, limiting temperatures in the
ionized gas to < 20,000 K. If radiation is the primary ionizing mechanism, the
Lyman continuum flux required to sustain the most strongly emitting ionized
regions is 1.2 x 10^6 photons cm^-2 s^-1. There appears to be no local, stellar
source capable of maintaining the ionization of the gas; however, the required
ionizing flux is consistent with current models of the escape of Lyman
continuum radiation from OB stars in the disk and of ionizing radiation
produced by cooling supernova remnants.Comment: 12 pages, 3 figures, Figure 1 is full color and a higher quality
version will be available on our web site. Published in Astrophysical Journal
(Letters). Visit http://www.astro.wisc.edu/wham/ for more informatio
Optical interconnect solution with plasmonic modulator and Ge photodetector array
We report on an optical chip-to-chip interconnect solution, thereby demonstrating plasmonics as a solution for ultra-dense, high-speed short-reach communications. The interconnect comprises a densely integrated plasmonic Mach-Zehnder modulator array that is packaged with standard driving electronics. On the receiver side, a germanium photodetector array is integrated with trans-impedance amplifiers. A multicore fiber provides a compact optical interface to the array. We demonstrate 4 Ă 20 Gb/s on-off keying signaling with direct detection.ISSN:1041-1135ISSN:1941-017
Geocoronal Hydrogen Observations Spanning Three Solar Minima
The 11-year solar cycle is a dominant source of natural variability in the upper atmosphere, and its effect on atomic hydrogen distributions and emissions must be understood to investigate possible signs of longer-term climatic trends in this region. We present midlatitude geocoronal hydrogen Balmer α observations from solar cycle 23 (1997â2006) and three solar minimum periods, 1985, 1997, and 2006. The 1997 through 2006 observations were taken with the Wisconsin H-αMapper Fabry-Perot (WHAM), a ground-based CCD-annular summing instrument that began observations at the Kitt Peak Observatory in Arizona in 1997. The 1985 observations were made with a similarly designed âpre-WHAMâ Fabry-Perot Interferometer utilizing photomultiplier detection and located in Wisconsin. WHAM has consistently observed higher column emission intensities during solar maximum periods than during solar minimum conditions, with the ratio dependent upon the viewing geometry. The observations from three solar minimum periods agree to within 18% uncertainties over most of the shadow altitude range. An analysis of recent Fabry-Perot observations of upper atmospheric hydrogen during solar cycle 23 and during three solar minima (1985, 1997, 2006) established a reference data set of highly precise, consistently calibrated, thermospheric plus exospheric hydrogen column emission observations from northern midlatitudes that can be used to compare with future observations
Detection of a Large Arc of Ionized Hydrogen Far Above the Cas OB6 Association: A Superbubble Blowout into the Galactic Halo?
The Wisconsin H-Alpha Mapper (WHAM) Northern Sky Survey has revealed a loop
of H II reaching 1300 pc from the Galactic midplane above the Cas OB6
association in the Perseus sprial arm. This enormous feature surrounds and
extends far above the "W4 Chimney" identified by Normandeau et al. and appears
to be associated with the star formation activity near the W3/W4/W5 H II region
complex. The existence of this ionized structure suggests that past episodes of
massive star formation have cleared the H I from an enormous volume above the
Perseus arm, allowing Lyman continuum photons from O stars near the Galactic
midplane to reach into the halo.Comment: 12 pages, 2 figures, accepted for publication in ApJ (Letters
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