The Prevalence of Carbon-13 in Respiratory Carbon Dioxide As an Indicator of the Type of Endogenous Substrate. The change from lipid to carbohydrate during the respiratory rise in potato slices

Isotope discrimination is a common feature of biosynthesis in nature, with the result that different classes of carbon compounds frequently display different 13C/12C ratios. The 13C/12C ratio of lipid in potato tuber tissue is considerably lower than that for starch or protein. We have collected respiratory CO2 from potato discs in successive periods through 24 hr from the time of cutting—an interval in which the respiration rate rises 3–5-fold. The 13C/12C ratio of the evolved CO2 was determined for each period, and compared with the 13C/12C ratios of the major tissue metabolites. In the first hours the carbon isotope ratio of the CO2 matches that of lipid. With time, the ratio approaches that typical of starch or protein. An estimation has been made of the contribution of lipid and carbohydrate to the total respiration at each juncture. In connection with additional observations, it was deduced that the basal, or initial, respiration represents lipid metabolism —- possibly the alpha-oxidation of long chain fatty acids -— while the developed repiration represents conventional tricarboxylic acid cycle oxidation of the products of carbohydrate glycolysis. The true isotopic composition of the respiratory CO2 may be obscured by fractionation attending the refixation of CO2 during respiration, and by CO2 arising from dissolved CO2 and bicarbonate preexisting in the tuber. Means are described for coping with both pitfalls

RISK EFFICIENCY OF ALTERNATE CANOLA MANAGEMENT DECISIONS

This study evaluates profitability and risk associated with eighteen different management decisions for canola production in Alberta. Expected payoff from cultivar selection outweighs the payoff from time of seeding and from time of weed control. Expected payoff was higher from hybrid compared to inbred cultivars. Early spring seeding was more profitable than fall or mid-May seeding. A typical decision in the sample showed positive and significant upper limit risk-expected return tradeoffs. The generalized stochastic dominance analysis revealed that early spring seeding was dominant over fall and mid-May seeding across all risk averse and risk neutral farmers. Weed control at the six-leaf stage was risk efficient for a risk averter. A risk neutral farmer preferred weed control at the three to four-leaf stage or six-leaf stage, depending on cultivar.Risk and Uncertainty,

Obstetrician-assessed maternal health at pregnancy predicts offspring future health

Background: We aimed to examine the association between obstetrician assessment of maternal physical health at the time of pregnancy and offspring cardiovascular disease risk.<p></p> Methods and Principal Findings: We examined this association in a birth cohort of 11,106 individuals, with 245,000 person years of follow-up. We were concerned that any associations might be explained by residual confounding, particularly by family socioeconomic position. In order to explore this we used multivariable regression models in which we adjusted for a range of indicators of socioeconomic position and we explored the specificity of the association. Specificity of association was explored by examining associations with other health related outcomes. Maternal physical health was associated with cardiovascular disease: adjusted (socioeconomic position, complications of pregnancy, birthweight and childhood growth at mean age 5) hazard ratio comparing those described as having poor or very poor health at the time of pregnancy to those with good or very good health was 1.55 (95%CI: 1.05, 2.28) for coronary heart disease, 1.91 (95%CI: 0.99, 3.67) for stroke and 1.57 (95%CI: 1.13, 2.18) for either coronary heart disease or stroke. However, this association was not specific. There were strong associations for other outcomes that are known to be related to socioeconomic position (3.61 (95%CI: 1.04, 12.55) for lung cancer and 1.28 (95%CI:1.03, 1.58) for unintentional injury), but not for breast cancer (1.10 (95%CI:0.48, 2.53)).<p></p> Conclusions and Significance: These findings demonstrate that a simple assessment of physical health (based on the appearance of eyes, skin, hair and teeth) of mothers at the time of pregnancy is a strong indicator of the future health risk of their offspring for common conditions that are associated with poor socioeconomic position and unhealthy behaviours. They do not support a specific biological link between maternal health across her life course and future risk of cardiovascular disease in her offspring.<p></p&gt

Dynamic Forms. Part 1: Functions

The formalism of dynamic forms is developed as a means for organizing and systematizing the design control systems. The formalism allows the designer to easily compute derivatives to various orders of large composite functions that occur in flight-control design. Such functions involve many function-of-a-function calls that may be nested to many levels. The component functions may be multiaxis, nonlinear, and they may include rotation transformations. A dynamic form is defined as a variable together with its time derivatives up to some fixed but arbitrary order. The variable may be a scalar, a vector, a matrix, a direction cosine matrix, Euler angles, or Euler parameters. Algorithms for standard elementary functions and operations of scalar dynamic forms are developed first. Then vector and matrix operations and transformations between parameterization of rotations are developed in the next level in the hierarchy. Commonly occurring algorithms in control-system design, including inversion of pure feedback systems, are developed in the third level. A large-angle, three-axis attitude servo and other examples are included to illustrate the effectiveness of the developed formalism. All algorithms were implemented in FORTRAN code. Practical experience shows that the proposed formalism may significantly improve the productivity of the design and coding process

Dynamic Forms

The paper describes a method for guiding a dynamic system through a given set of points. The paradigm is a fully automatic aircraft subject to air traffic control (ATC). The ATC provides a sequence of waypoints through which the aircraft trajectory must pass. The waypoints typically specify time, position, and velocity. The guidance problem is to synthesize a system state trajectory that satisfies both the ATC and aircraft constraints. Complications arise because the controlled process is multidimensional, multiaxis, nonlinear, highly coupled, and the state space is not flat. In addition, there is a multitude of operating modes, which may number in the hundreds. Each such mode defines a distinct state space model of the process by specifying the state space coordinatization, the partition of the controls into active controls and configuration controls, and the output map. Furthermore, mode transitions are required to be smooth. The proposed guidance algorithm is based on the inversion of the pure feedback approximation, followed by correction for the effects of zero dynamics. The paper describes the structure and major modules of the algorithm, and the performance is illustrated by several example aircraft maneuvers

RXTE monitoring observations of Markarian 3

We present Rossi X-ray Timing Explorer, monitoring observations of the Seyfert 2 galaxy Markarian 3 spanning a 200 day period during which time the source flux varied by a factor $\sim 2$ in the 4-20 keV bandpass. In broad agreement with earlier Ginga results, the average spectrum can be represented in terms of a simple spectral model consisting of a very hard power-law continuum ($\Gamma \approx 1.1$) modified below $\sim 6$ keV by a high absorbing column ($N_H\sim 6\times 10^{23}$ \cunits) together with a high equivalent width Fe-K emission feature at 6.4 keV. The abnormally flat spectral index is probably the signature of a strong reflection component and we consider two models incorporating such emission. In the first the reflected signal suffers the same absorption as the intrinsic continuum, whereas in the second the reflection is treated as an unabsorbed spectral component. In the former case, we require a very strong reflection signal ($R ~< 3$) in order to match the data; in addition variability of both the intrinsic power-law and the reflection component is required. The unabsorbed reflection model requires a somewhat higher line-of-sight column density to the nuclear source ($\sim 10^{24}$ \cunits), but in this case the reflected signal remains constant whilst the level of the intrinsic continuum varies. The latter description is consistent with the reflection originating from the illuminated far inner wall of a molecular torus, the nearside of which screens our direct view of the central continuum source.Comment: 7 pages, submitted to the MNRA

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Electrodeposition from supercritical fluids

Recent studies have shown that it is possible to electrodeposit a range of materials, such as Cu, Ag and Ge, from various supercritical fluids, including hydrofluorocarbons and mixtures of CO2 with suitable co-solvents. In this perspective we discuss the relatively new field of electrodeposition from supercritical fluids. The perspective focuses on some of the underlying physical chemistry and covers both practical and scientific aspects of electrodeposition from supercritical fluids. We also discuss possible applications for supercritical fluid electrodeposition and suggest some key developments that are required to take the field to the next stage