Energy and biological evolution—II. The mathematical structure of equilibrium states

We examine certain mathematical structures presented in Part I. The most important of these are the energy structures determined by the couple (ω×E, ψ) the space of causality defined by ψ^-1(0) and the notion of collapsibility, i.e., the descent of a species from a higher to a lower equilibrium configuration as a result of energy loss. This work was supported by an Associateship of The International Centre for Theoretical Physics, P.O. Box 586, Miramare, 34100 Trieste, Italy.     

Validity of U.S. Nutritional Surveillance: National Health and Nutrition Examination Survey Caloric Energy Intake Data, 1971–2010

Importance

Methodological limitations compromise the validity of U.S. nutritional surveillance data and the empirical foundation for formulating dietary guidelines and public health policies.

Objectives

Evaluate the validity of the National Health and Nutrition Examination Survey (NHANES) caloric intake data throughout its history, and examine trends in the validity of caloric intake estimates as the NHANES dietary measurement protocols evolved.

Design

Validity of data from 28,993 men and 34,369 women, aged 20 to 74 years from NHANES I (1971–1974) through NHANES 2009–2010 was assessed by: calculating physiologically credible energy intake values as the ratio of reported energy intake (rEI) to estimated basal metabolic rate (BMR), and subtracting estimated total energy expenditure (TEE) from NHANES rEI to create ‘disparity values’.

Main Outcome Measures

1) Physiologically credible values expressed as the ratio rEI/BMR and 2) disparity values (rEI–TEE).

Results

The historical rEI/BMR values for men and women were 1.31 and 1.19, (95% CI: 1.30–1.32 and 1.18–1.20), respectively. The historical disparity values for men and women were −281 and −365 kilocalorie-per-day, (95% CI: −299, −264 and −378, −351), respectively. These results are indicative of significant under-reporting. The greatest mean disparity values were −716 kcal/day and −856 kcal/day for obese (i.e., ≥30 kg/m2) men and women, respectively.

Conclusions

Across the 39-year history of the NHANES, EI data on the majority of respondents (67.3% of women and 58.7% of men) were not physiologically plausible. Improvements in measurement protocols after NHANES II led to small decreases in underreporting, artifactual increases in rEI, but only trivial increases in validity in subsequent surveys. The confluence of these results and other methodological limitations suggest that the ability to estimate population trends in caloric intake and generate empirically supported public policy relevant to diet-health relationships from U.S. nutritional surveillance is extremely limited.     

Energy vs. essential fatty acids: what do scallop larvae (Argopecten purpuratus) need most?

Larvae of the Chilean–Peruvian scallop Argopecten purpuratus were fed a Dunaliella tertiolecta diet (Dun-diet) supplemented with lipid emulsions, rich in 20:5n-3 (EmEPA), 22:6n-3 (EmDHA) or in saturated fatty acids (EmCOCO). A mixed algal diet of Isochrysis galbana (T-iso) and Chaetoceros neogracile served as a positive control (St-diet). Lipid supplementation to the Dun-diet improved the larval growth and increased the percentage of eyed larvae significantly, compared to the non-supplemented Dun-diet because of the extra energy supplied and not because of its fatty acid composition. No significant differences were observed between supplementation with EmEPA, EmDHA or EmCOCO. A mixture of 20% EmEPA+20% EmDHA (40% EmHUFA) was more efficient in raising the total lipid content in larvae than 40% EmCOCO. Both emulsions increased the triacylglycerol content in larvae compared to the non-supplemented Dun-diet. The best result, however, was obtained with the St-diet, probably because of a more suitable 18:2n-6/18:3n-3 ratio and a higher level of arachidonic acid. A positive relationship between the 18:2n-6/18:3n-3 ratio and the larval performance was found. No significant difference was observed in post-settlement larval size or percentage of metamorphosed larvae between the St-diet and the St-diet supplemented with 20% EmHUFA or 20% EmCOCO. The metamorphosed larvae had a constant DHA/EPA ratio of 3.7, independent from the diet, which suggested a metabolic control of the two fatty acids and a species-dependency of the ratio.     

The Obesity Epidemic: A Consequence of Reduced Energy Expenditure and the Uncoupling of Energy Intake?

Obesity prevalence has increased, and increased energy intake or decreased physical activity are the two most obvious contributing factors. The percentage of Americans engaging in exercise has been stable over the past few decades, but decreases in occupation‐related energy expenditure are sufficient to partially explain increased obesity prevalence. Further, the contribution of energy intake and energy expenditure to the obesity epidemic is complicated because they are not independent—they are influenced by each other. For example, Mayer found that low activity levels were marked by higher body weight and higher “unregulated” energy intake levels. Conversely, higher activity levels were marked by lower body weight and energy intake that matched energy expenditure. Consistent with Mayer, we propose that because most Americans have low levels of occupation‐related activity, they do not benefit from the regulation of energy intake achieved at higher activity levels, resulting in weight gain due to energy intake exceeding energy expenditure.     

Uncoupling Protein—A Useful Energy Dissepator

The structure/function relationship in the uncoupling proteins (UCP) is reviewed, stressingUCP from brown adipose tissue (UCP1) since, so far, nearly no biochemistry is known forthe UCP variants UCP2, UCP3, and UCP4. The transport for H⁺ and Cl^– and its dependenceon fatty acids in reconstituted vesicles is described. The inhibition and binding of nucleotidesto UCP1, in particular, the pH dependence and two-stage binding are analyzed. A model forthe role of fatty acid in H⁺ transport is shown. The role of specific residues in UCP1 isanalyzed by directed mutagenesis in a yeast expression system. The different regulation bythe cellular energy potential of UCP1 versus UCP3 is discussed.     

Marginal Land-based Biomass Energy Production in China

Fast economic development in China has resulted in a significant increase in energy demand. Coal accounts for 70% of China's primary energy consumption and its combustion has caused many environmental and health problems. Energy security and environmental protection requirements are the main drivers for renewable energy development in China. Small farmland and food security make bioenergy derived from corn or sugarcane unacceptable to China: the focus should be on generating bioenergy from lignocellulosic feedstock sources. As China cannot afford biomass energy production from its croplands, marginal lands may play an important role in biomass energy production. Although on a small scale, marginal land has already been used for various purposes. It is estimated that some 45 million hm2 of marginal land could be brought into high potential biomass energy production. For the success of such an initiative, it will likely be necessary to develop multipurpose plants. A case study, carried out on marginal land in Ningnan County, Sichuan Province with per capita cropland of 0.07 ha, indicated that some 380 000 tons of dry biomass could be produced each year from annual pruning of mulberry trees. This study supports the feasibility of producing large quantities of biomass from marginal land sources.     

SINGLE MATERIAL SOLAR CELLS: Single Material Solar Cells: the Next Frontier for Organic Photovoltaics? (Adv. Energy Mater. 2/2011)

An overview of various approaches for the realization of single‐material organic solar cells (SMOCs) is presented. Fullerene‐conjugated systems dyads, di‐block copolymers, and self‐organized donor‐acceptor molecules all represent different possible approaches towards SMOCs. Although each of them presents specific advantages and poses specific problems of design and synthesis, these different routes have witnessed significant progress in the past few years and SMOCs with efficiencies in the range of 1.50% have been realized. These performances are already higher than those of bi‐component bulk heterojunction solar cells some ten years ago, demonstrating that SMOCs can represent a credible approach towards efficient and simple organic solar cells. Possible directions for future research are discussed with the aim of stimulating further research on this exciting topic.     

Effect of the Vibrational/Rotational Energy Partitioning on the Energy Transfer in Atom–Triatomic Molecule Collisions

The effect of the initial partitioning of the molecular energy between vibrational and rotational modes of a triatomic molecule on the collisional energy transfer is studied for a model atom–triatomic molecule system. We considered the collisions of thermal bath Ar atoms with SO2 molecules, and used the trajectory calculations for determining the energy transfer for three different samplings of initial conditions of the molecule. The first sampling method generated the microcanonical distribution over all states, entering into the vibrational and rotational manifolds, while two others produced distributions with relatively lower values of the rotational energies. It is shown that both the average energy transfer per collision and the mechanism of the energy exchange are significantly affected by the vibrational/rotational energy partitioning before the collisions. Relative decrease in the rotational energy results in the decrease of the averaged energy transfer and progressively emphasizes the role of active rotation as the gateway for translation-vibration energy exchange.