As-received microstructure of a SiC/Ti-15-3 composite

A silicon carbide fiber reinforced titanium (Ti-15V-3Cr-3Sn-3Al) composite is metallographically examined. Several methods for examining composite materials are investigated and documented. Polishing techniques for this material are described. An interference layering method is developed to reveal the structure of the fiber, the reaction zone, and various phases within the matrix. Microprobe and transmission electron microscope (TEM) analyses are performed on the fiber/matrix interface. A detailed description of the fiber distribution as well as the microstructure of the fiber and matrix are presented

Assessment of Myocardial Metabolism with 11C-palmitate. Comparison with 123I-heptadecanoic acid

Carbon-11 (11C)-palmitate is chemically identical to its physiological counterpart. After intravenous injection the myocardial distribution of 11C-activity can be measured accurately by positron emission tomography. Regions of decreased 11C-palmitate uptake can be readily identified and their size quantified. Results obtained in dogs with experimental coronary thrombosis and in patients with myocardial infarction indicate that positron emission tomography with 11C-palmitate allows non-invasive assessment of the metabolic recovery of the myocardium after lysis of the occluding coronary thrombus. There is experimental evidence that the rate of clearance of 11C-palmitate activity from the myocardium is related to oxidative fatty acid metabolism. In dogs, a restriction of the oxygen supply to the myocardium results in a decrease in the rate of 11C-clearance independently of whether myocardial perfusion is concomitantly reduced or not. Similarities in myocardial uptake and clearance exist between iodine-123 (123I)-heptadecanoic acid and 11C-palmitate. However, interpretation of the kinetics of the radio-iodinated fatty acid analogue has to take into account the different intracellular fate of the iodine label compared with the fatty acid structur

Gravity model improvement using GEOS-3 (GEM 9 and 10)

The use of collocation permitted GEM 9 to be a larger field than previous derived satellite models, GEM 9 having harmonics complete to 20 x 20 with selected higher degree terms. The satellite data set has approximately 840,000 observations, of which 200,000 are laser ranges taken on 9 satellites equipped with retroreflectors. GEM 10 is complete to 22 x 22 with selected higher degree terms out to degree and order 30 amounting to a total of 592 coefficients. Comparisons with surface gravity and altimeter data indicate a substantial improvement in GEM 9 over previous satellite solutions; GEM 9 is in even closer agreement with surface data than the previously published GEM 6 solution which contained surface gravity. In particular the free air gravity anomalies calculated from GEM 9 and a surface gravity solution are in excellent agreement for the high degree terms

GEOS I tracking station positions on the SAO standard earth /C-5/

GEOS 1 tracking station positions on SAO standard earth C-5 mode

Determination of some dominant parameters of the global dynamic sea surface topography from GEOS-3 altimetry

The 1977 altimetry data bank is analyzed for the geometrical shape of the sea surface expressed as surface spherical harmonics after referral to the higher reference model defined by GEM 9. The resulting determination is expressed as quasi-stationary dynamic SST. Solutions are obtained from different sets of long arcs in the GEOS-3 altimeter data bank as well as from sub-sets related to the September 1975 and March 1976 equinoxes assembled with a view to minimizing seasonal effects. The results are compared with equivalent parameters obtained from the hydrostatic analysis of sporadic temperature, pressure and salinity measurements of the oceans and the known major steady state current systems with comparable wavelengths. The most clearly defined parameter (the zonal harmonic of degree 2) is obtained with an uncertainty of + or - 6 cm. The preferred numerical value is smaller than the oceanographic value due to the effect of the correction for the permanent earth tide. Similar precision is achieved for the zonal harmonic of degree 3. The precision obtained for the fourth degree zonal harmonic reflects more closely the accuracy expected from the level of noise in the orbital solutions

Watershed Vulnerability To Herbicide Transport in Northern Missouri and Southern Iowa Streams

Herbicide contamination of streams has been well documented, but little is currently known about the specific factors affecting watershed vulnerability to herbicide transport. The primary objectives of this study were (1) to document herbicide occurrence and transport from watersheds in the northern Missouri/ southern Iowa region; (2) to quantify watershed vulnerability to herbicide transport and relate vulnerability to soil properties; and (3) to compute the contribution of this region to the herbicide load of the Missouri and Mississippi Rivers. Grab samples were collected under baseflow and runoff conditions at 21 hydrologic monitoring stations between April 15 and July 15 from 1996 to 1999. Samples were analyzed for commonly used soil-applied herbicides (atrazine, cyanazine, acetochlor, alachlor, metolachlor, and metribuzin) and four triazine metabolites (deisopropylatrazine, deethylatrazine, hydroxyatrazine, and cyanazine amide). Estimates of herbicide load and relative losses were computed for each watershed. Median parent herbicide losses, as a percentage of applied, ranged from 0.33 to 3.9%; loss rates that were considerably higher than other areas of the United States. Watershed vulnerability to herbicide transport, measured as herbicide load per treated area, showed that the runoff potential of soils was a critical factor affecting herbicide transport. Herbicide transport from these watersheds contributed a disproportionately high amount of the herbicide load to both the Missouri and Mississippi Rivers. Based on these results, this region of the Corn Belt is highly vulnerable to transport of herbicides from fields to streams, and it should be targeted for implementation of management practices designed to reduce herbicide losses in surface runoff

Changes in Glenohumeral Kinematics after a Competitive Season in Collegiate Baseball Pitchers

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Collateral Damage: American Science and the War on Terrorism

In the wake of the terrorist attacks of 2001, the United States government undertook a rushed effort to increase security. In addition to new legislation such as the Patriot Act and the Homeland Security Act of 2002, the government dramatically ramped up enforcement of laws that have long been on the books, and revised its policies to deal with new terrorist threats. While the need for increased security is undeniable, the costs of security measures need to be weighed as well, in terms of collateral damage they produce to the U.S. science and engineering (S&E) enterprise. That was the message of a panel discussion held at the June 2004 IEEE-SSIT International Symposium on Technology and Society (ISTAS\u2704) in Worcester, MA [1]. We focus here on two main problems: the increasing difficulties faced by students and scientists from abroad in obtaining visas to visit and study in the United States, and the barriers that are being erected to communication and collaboration between U.S. investigators and international scholars

Absence of fermionic quasi-particles in the superfluid state of the attractive Fermi gas

We calculate the effect of order parameter fluctuations on the fermionic single-particle excitations in the superfluid state of neutral fermions interacting with short range attractive forces. We show that in dimensions D \leq 3 the singular effective interaction between the fermions mediated by the gapless Bogoliubov-Anderson mode prohibits the existence of well-defined quasi-particles. We explicitly calculate the single-particle spectral function in the BEC regime in D=3 and show that in this case the quasi-particle residue and the density of states are logarithmically suppressed.Comment: 4 RevTex pages, 3 figures; title changed, new Figure 1, added references. We argue that in the entire regime of the BCS-BEC crossover the quasi-particle picture breaks down in D <=3 for neutral fermions (but NOT for charged fermions

Retinoic acids increase expression of GLUT4 in dedifferentiated and hypertrophied cardiac myocytes

Sufficient expression of the insulin-sensitive glucose transporter GLUT4 may be crucial for the survival of cardiac myocytes in situations of stress. Expression of GLUT4 in cardiac myocytes correlates with cell differentiation and is reduced in the hypertrophied and failing myocardium. Adult rat cardiomyocytes (ARC) in primary culture undergo dedifferentiation and reduction of GLUT4 expression. Depending on the culture condition partial redifferentiation and/or hypertrophy follows. All-trans (at) and 9-cis retinoic acids (RA) are morphogenetic agents important for cell differentiation. Both atRA and 9-cisRA restored GLUT4 expression in dedifferentiated ARC, while only 9-cisRA could increase GLUT4 expression in hypertrophic ARC. The effects of RA were associated with improved differentiation of the cardiac myocytes, as assessed from the expression of atrial natriuretic factor and the morphology of the contractile apparatus. In neonatal rat cardiomyocytes, 9-cisRA, but not atRA, stimulated transcription from the glut4 promoter. In conclusion, treatment with RA can restore the down-regulated expression of GLUT4 in cardiomyocytes in association with a partial improvement of the differentiated phenotyp