Synthesis of carbon nanosheets by inductively coupled radio-frequency plasma enhanced chemical vapor deposition

An ultrathin sheet-like carbon nanostructure, carbon nanosheet, has been effectively synthesized with CH₄ diluted in H₂ by an inductively coupled radio-frequency plasma enhanced chemical vapor deposition. Nanosheets were obtained without catalyst over a wide range of deposition conditions and on a variety of substrates, including metals, semiconductors and insulators. Scanning electron microscopy shows that the sheet-like structures stand on edge on the substrate and have corrugated surfaces. The sheets are 1 nm or less in thickness and have a defective graphite structure. Raman spectra show typical carbon features with D and G peaks at 1350 and 1580 cm⁻¹, respectively. The intensity ratio of these two peaks, I(D)/I(G), increases with methane concentration or substrate temperature, indicating that the crystallinity of the nanosheets decreases. Infrared and thermal desorption spectroscopies reveal hydrogen incorporation into the carbon nanosheets.     

Quantum Effects in Three-Dimensional H + D2 Reaction at High Energies

The H + D₂ reactive system was studied in the energy range 0.84 < E_tr < 2.70 eV employing the ordinary Quasi-Classical Trajectory Approach (QCTA), the Classical and the Quantum Reactive Infinite Order Sudden Approximations (CRIOSA and QRIOSA), and the Angle-Oriented Transition State Theory (AOTST). From a detailed analysis of the various integral cross-sections and opacity functions, it was concluded that pronounced quantum effects ( > 10%) are expected in the high-energy region (≤ 2 eV).     

Detection and analysis of quantitative trait loci affecting production and secondary traits on chromosome 7 in Israeli Holsteins

A total of 5,459 Israeli Holstein cows, daughters of 11 sires, were genotyped for 29 microsatellites spanning chromosome 7 and analyzed by the daughter design for 9 economic traits: milk, fat, and protein yield, fat and protein percentage, somatic cell score, female fertility, herd life, and milk persistency. Quantitative trait loci at chromosome-wise 0.05 significance were obtained for fat and protein yield, fat percentage, somatic cell score, and female fertility. Peak F-values were obtained at 29 cM for fat and protein yield and fat percentage, at 60 cM for somatic cell score, at 74 cM for herd life, and at 11 cM for female fertility. The 0.95 confidence intervals for quantitative trait loci locations were 20 cM for kilograms of fat, 27 cM for fertility, and 51 cM for somatic cell score. Two loci affecting fertility at opposite ends of the chromosome are apparently segregating in the population. A quantitative trait locus for fertility near the centromere was confirmed by application of the modified granddaughter design to a single family. Estimated frequency of the economically favorable allele in the Israeli Holstein cattle was less than 0.5. Significant genetic gain for fertility seems possible by marker-assisted selection.     

Medical care utilization in a regional prepaid medical system

Aggregate dollar medical care utilization is estimated by applying a fee structure to 1967–70 medical care utilization of 3,418 members of the Kaiser Foundation Health Plan of Portland, Oregon. The data indicated a very stable pattern of medical care utilization by the cohort during the period. The average yearly increase in medical care dollar utilization per person (prices constant) was only 1.5 percent. There was some tendency for resource utilizaton to become more concentrated among the highest users. Inpatient services accounted for about 40 percent of the dollar utilization with no tendency to decline or rise over the fouryear period. While age and death were the only factors significantly associated with the likelihood of being a high user in a given year ($2,500 threshold), family size, education, and sex joined these factors in being associated with medical care dollar utilization by an individual. Family size was negatively related while education and being female were related directly to dollar utilization. A limited comparison is made with experience in the U.S.This research was supported by Grant No. 5 RO1 HS-01653, awarded by the National Center of Health Services Research, HRA. Technical support was given by the Health Services Research Center, Kaiser Foundation Hospitals, Portland, Oregon.     

Computer Systems Based on Silicon Photonic Interconnects

We present a computing microsystem that uniquely leverages the bandwidth, density, and latency advantages of silicon photonic interconnect to enable highly compact supercomputer-scale systems. We describe and justify single-node and multinode systems interconnected with wavelength-routed optical links, quantify their benefits vis-a-vis electrically connected systems, analyze the constituent optical component and system requirements, and provide an overview of the critical technologies needed to fulfill this system vision. This vision calls for more than a hundredfold reduction in energy to communicate an optical bit of information. We explore the power dissipation of a photonic link, suggest a roadmap to lower the energy-per-bit of silicon photonic interconnects, and identify the challenges that will be faced by device and circuit designers towards this goal.     

Gamma linolenic acid attenuates cardiovascular responses to stress in borderline hypertensive rats

The purpose of the present study was to investigate the effects of gamma linolenic acid (GLA) on cardiovascular responses to psychosocial stress (isolation) and to pressor hormones in the genetically borderline hypertensive rat (SHR×WKY). Adult male SHR×WKY were divided into two groups following five weeks of group housing. One group (GLA) received eight weeks constant flow osmotic pumps releasing 0.04 mg GLA in olive oil/kg-hr, while the second group received dummy pumps (DUM). One week following pump implantation, each group was divided into two subgroups and exposed to a four-week experimental period of either continued group housing (no stress) or isolation (stress). A two-week recovery period of group housing followed the experimental period. Blood pressure and heart rate were determined weekly by the tail cuff technique. At the end of the recovery period, animals in the no stress condition were anesthetized and received an arterial cannula for NOR and ANG infusion and direct BP recording. Then the responses to an ED₅₀ of NOR and ANG were determined. All animals were then killed for determination of heart weight and adrenal weight. All groups had mean control period systolic BP values ranging from 143–146 mm Hg. In the no stress condition, neither GLA nor DUM altered BP over the course of the study. However, BP increased in the DUM group durign all four weeks of the isolation period vs the control period (p<0.01), whereas BP increased only in week 1 in the GLA group (p<0.05). Heart rate increased during stress in the DUM group (p<0.05), but not in the GLA group. Vascular reactivity to NOR was unaffected by GLA administration. In contrast, GLA increased the duration of the pressor response to ANG (p<0.01), but tended to decrease the magnitude of the pressor response (p<0.09) vs DUM. GLA had no effect on heart weight/body weight ratio. Adrenal weight/body weight ratio was lower in the DUM/no stress group than all other treatment groups. These data indicate that GLA administration attenuates the cardiovascular responses to chronic stress in animals with a genetic predisposition to hypertension, in the absence of an effect on resting BP. They also demonstrate a limitation of GLA effect, in mature animals, to epigenetic pressor factors. Furthermore, GLA action may involve an alteration of the cardiovascular responses to ANG, but not NOR. These findings suggest that GLA may be useful in preventing the neurogenic triggering of hypertension by chronic stress in genetically stress-sensitive animals.     

Smokers' beliefs about the relative safety of other tobacco products: findings from the ITC collaboration.

Most tobacco control efforts in western countries focus on the factory-made, mass-produced (FM) cigarette, whereas other tobacco products receive relatively little attention. Noncombusted tobacco products (i.e., referred to as smokeless tobacco), particularly Swedish-style snus, carry lower disease risks, compared with combusted tobacco products such as cigarettes. In this context, it is important to know what tobacco users believe about the relative harmfulness of various types of tobacco products. Data for this study came from random-digit-dialed telephone surveys of current smokers aged 18 or older in Australia, Canada, the United Kingdom, and the United States. Three waves of data, totaling 13,322 individuals, were assessed. Items assessed use of and beliefs about the relative harms of cigars, pipes, smokeless tobacco, and FM and roll-your-own cigarettes, as well as sociodemographics and smoking behaviors. Cigars (2.8%-12.7%) were the other tobacco products most commonly used by current cigarette smokers, followed by pipes (0.3%-2.1%) and smokeless tobacco (0.0%-2.3%). A significant minority of smokers (12%-21%) used roll-your-own cigarettes at least some of the time. About one-quarter of smokers believed that pipes, cigars, or roll-your-own cigarettes were safer than FM cigarettes, whereas only about 13% responded correctly that smokeless tobacco was less hazardous than cigarettes. Multivariate analyses showed that use of other tobacco products was most strongly related to beliefs about the reduced harm of these other products. Use of other tobacco products was low but may be growing among smokers in the four countries studied. Smokers are confused about the relative harms of tobacco products. Health education efforts are needed to correct smoker misperceptions.