Brain mass estimation by head circumference and body mass methods in neonatal glycaemic modelling and control

Introduction

Hyperglycaemia is a common complication of stress and prematurity in extremely low-birth-weight infants. Model-based insulin therapy protocols have the ability to safely improve glycaemic control for this group. Estimating non-insulin-mediated brain glucose uptake by the central nervous system in these models is typically done using population-based body weight models, which may not be ideal.

Method

A head circumference-based model that separately treats small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) infants is compared to a body weight model in a retrospective analysis of 48 patients with a median birth weight of 750 g and median gestational age of 25 weeks. Estimated brain mass, model-based insulin sensitivity (S_I) profiles, and projected glycaemic control outcomes are investigated. SGA infants (5) are also analyzed as a separate cohort.

Results

Across the entire cohort, estimated brain mass deviated by a median 10% between models, with a per-patient median difference in S_I of 3.5%. For the SGA group, brain mass deviation was 42%, and per-patient S_I deviation 13.7%. In virtual trials, 87–93% of recommended insulin rates were equal or slightly reduced (Δ < 0.16 mU/h) under the head circumference method, while glycaemic control outcomes showed little change.

Conclusion

The results suggest that body weight methods are not as accurate as head circumference methods. Head circumference-based estimates may offer improved modelling accuracy and a small reduction in insulin administration, particularly for SGA infants.     

The role of sustainable agriculture and renewable-resource management in reducing greenhouse-gas emissions and increasing sinks in China and India

This paper contains an analysis of the technical options in agriculture for reducing greenhouse-gas emissions and increasing sinks, arising from three distinct mechanisms: (i) increasing carbon sinks in soil organic matter and above-ground biomass; (ii) avoiding carbon emissions from farms by reducing direct and indirect energy use; and (iii) increasing renewable-energy production from biomass that either substitutes for consumption of fossil fuels or replaces inefficient burning of fuelwood or crop residues, and so avoids carbon emissions, together with use of biogas digesters and improved cookstoves. We then review best-practice sustainable agriculture and renewable-resource-management projects and initiatives in China and India, and analyse the annual net sinks being created by these projects, and the potential market value of the carbon sequestered. We conclude with a summary of the policy and institutional conditions and reforms required for adoption of best sustainability practice in the agricultural sector to achieve the desired reductions in emissions and increases in sinks. A review of 40 sustainable agriculture and renewable-resource-management projects in China and India under the three mechanisms estimated a carbon mitigation potential of 64.8 MtC yr(-1) from 5.5 Mha. The potential income for carbon mitigation is $324 million at $5 per tonne of carbon. The potential exists to increase this by orders of magnitude, and so contribute significantly to greenhouse-gas abatement. Most agricultural mitigation options also provide several ancillary benefits. However, there are many technical, financial, policy, legal and institutional barriers to overcome.     

Affect and the overjustification effect.

Studied the role of affect as a mediator of the overjustification effect and proposed that negative affect has a critical detrimental influence on intrinsic motivation, either as a reaction derived from self-perception and evaluation processes or as a factor that acts independently of these cognitive activities. Two studies, with 180 undergraduates, used the typical overjustification paradigm to test these hypotheses. In Exp I, the overjustification effect was successfully replicated for both behavioral and self-report measures of intrinsic motivation. It is important that the negative affect paralleled these results and was greatest in those conditions in which intrinsic motivation was predicted and found to be low (e.g., expected reward). In Exp II, affect was directly manipulated, independently of the cognitive manipulations. Results show that the induced positive affect erased the decrease in intrinsic motivation that was observed in Exp I. It is suggested that what determines the decrease in intrinsic interest in any activity is, in part, the amount of negative affect that becomes associated with the activity. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of interfacial reaction kinetics of I(aq) with Ag2O(s) on Ag substrate: Determining mass transport and surface reaction rates

The reaction kinetics of AgI formation by reaction of Ag₂O films with aqueous iodide were followed by monitoring the open-circuit potential (E_OC). Previous studies have shown that complete conversion of Ag₂O to AgI is indicated by an abrupt transition in the E_OC from a value close to the equilibrium potential for the Ag|Ag₂O|H₂O system to one close to that for Ag|AgI|I⁻, allowing an easy determination of the total reaction time, τ_f. The solid–solution interfacial kinetic parameters can then be determined by measuring τ_f as a function of the initial amount of Ag₂O and the I⁻ concentration. In this study, the application of the technique was extended to examine the effect of I⁻(aq) transport to an Ag₂O surface by measuring τ_f as a function of electrode rotation rate. By studying the chemical conversion as a function of electrode rotation rate we are able to separate mass transport effects from the reaction kinetics. The interfacial reaction follows kinetics typical of a sequential binary-reaction system consisting of mass transport to, followed by reaction at, the surface. The mass transport rate was proportional to the square root of the electrode rotation rate, consistent with the well-established diffusion-boundary layer model for a rotating disc. Varying the rotation rate allows a quantitative extrapolation of the data to the infinite rotation rate to determine the chemical reaction rate at the surface.     

Resource-conserving agriculture increases yields in developing countries

Despite great recent progress, hunger and poverty remain widespread and agriculturally driven environmental damage is widely prevalent. The idea of agricultural sustainability centers on the need to develop technologies and practices that do not have adverse effects on environmental goods and services, and that lead to improvements in food productivity. Here we show the extent to which 286 recent interventions in 57 poor countries covering 37 M ha (3% of the cultivated area in developing countries) have increased productivity on 12.6 M farms while improving the supply of critical environmental services. The average crop yield increase was 79% (geometric mean 64%). All crops showed water use efficiency gains, with the highest improvement in rainfed crops. Potential carbon sequestered amounted to an average of 0.35 t C ha(-1) y(-1). If a quarter of the total area under these farming systems adopted sustainability enhancing practices, we estimate global sequestration could be 0.1 Gt C y(-1). Of projects with pesticide data, 77% resulted in a decline in pesticide use by 71% while yields grew by 42%. Although it is uncertain whether these approaches can meet future food needs, there are grounds for cautious optimism, particularly as poor farm households benefit more from their adoption.     

Environmental costs of freshwater eutrophication in England and Wales

Eutrophication has many known consequences, but there are few data on the environmental and health costs. We developed a new framework of cost categories that assess both social and ecological damage costs and policy response costs. These findings indicate the severe effects of nutrient enrichment and eutrophication on many sectors of the economy. We estimate the damage costs of freshwater eutrophication in England and Wales to be $105-160 million yr(-1) (pound 75.0-114.3 m). The policy response costs are a measure of how much is being spent to address this damage, and these amount to $77 million yr(-1) pound 54.8 m). The damage costs are dominated by seven items each with costs of $15 million yr(-1) or more: reduced value of waterfront dwellings, drinking water treatment costs for nitrogen removal, reduced recreational and amenity value of water bodies, drinking water treatment costs for removal of algal toxins and decomposition products, reduced value of nonpolluted atmosphere, negative ecological effects on biota, and net economic losses from the tourist industry. In common with other environmental problems, it would represent net value (or cost reduction) if damage was prevented at source. A variety of effective economic, regulatory, and administrative policy instruments are available for internalizing these costs.     

Trends in stature in the South Australian Aboriginal Murraylands

Energy minimization calculations were used to generate secondary structures of partial and full-length myotonic dystrophy messenger RNAs (DMPK mRNAs) carrying variable numbers of CUG triplet repeats (n = 0 to 500). The results suggest that (1) unitary hairpins are the most stable structures formed; (2) long-axis distances of unfolded hairpins are directly proportional to CUG repeat numbers; and (3) hairpins composed of CUG repeats might form interstem clusters that are stabilized by hydrogen or ionic bonds. A model is proposed whereby DMPK mRNAs are sterically impeded from transport through nuclear pores, by giant hairpins or hairpin clusters formed by CUG repeats above a limit size (n > or = 44).     

BT Transform — an IP-enabled business platform

This paper describes how the concept of an IP-enabled infrastructure has been developed to deliver the next generation of ICT-based services. It will explore how the basic capability has been extended out into the customer’s premises and used to build more comprehensive solutions. In particular, it will look at the service layer as the pivot for component integration and as the key for providing an holistic family of capabilities. This is underpinned by an operational support systems infrastructure, aligned to emerging industry standards and which places more control in the end customer’s hands. Finally we will show how this capability, which is already rolled out to a number of large clients, fits closely with BT’s next generation network architecture strategy.     

Clustering of periodic multichannel timeseries data with application to plasma fluctuations

A periodic datamining algorithm has been developed and used to extract distinct plasma fluctuations in multichannel oscillatory timeseries data. The technique uses the Expectation Maximisation algorithm to solve for the maximum likelihood estimates and cluster assignments of a mixture of multivariate independent von Mises distributions (EM-VMM). The performance of the algorithm shows significant benefits when compared to a periodic k-means algorithm and clustering using non-periodic techniques on several artificial datasets and real experimental data. Additionally, a new technique for identifying interesting features in multichannel oscillatory timeseries data is described (STFT-clustering). STFT-clustering identifies the coincidence of spectral features over most channels of a multi-channel array using the averaged short time Fourier transform of the signals. These features are filtered using clustering to remove noise. This method is particularly good at identifying weaker features and complements existing methods of feature extraction. Results from applying the STFT-clustering and EM-VMM algorithm to the extraction and clustering of plasma wave modes in the time series data from a helical magnetic probe array on the H-1NF heliac are presented.     

Tight glycemic control in critical care--the leading role of insulin sensitivity and patient variability: a review and model-based analysis

Tight glycemic control (TGC) has emerged as a major research focus in critical care due to its potential to simultaneously reduce both mortality and costs. However, repeating initial successful TGC trials that reduced mortality and other outcomes has proven difficult with more failures than successes. Hence, there has been growing debate over the necessity of TGC, its goals, the risk of severe hypoglycemia, and target cohorts.This paper provides a review of TGC via new analyses of data from several clinical trials, including SPRINT, Glucontrol and a recent NICU study. It thus provides both a review of the problem and major background factors driving it, as well as a novel model-based analysis designed to examine these dynamics from a new perspective. Using these clinical results and analysis, the goal is to develop new insights that shed greater light on the leading factors that make TGC difficult and inconsistent, as well as the requirements they thus impose on the design and implementation of TGC protocols.A model-based analysis of insulin sensitivity using data from three different critical care units, comprising over 75,000 h of clinical data, is used to analyse variability in metabolic dynamics using a clinically validated model-based insulin sensitivity metric (S_I). Variation in S_I provides a new interpretation and explanation for the variable results seen (across cohorts and studies) in applying TGC. In particular, significant intra- and inter-patient variability in insulin resistance (1/S_I) is seen be a major confounder that makes TGC difficult over diverse cohorts, yielding variable results over many published studies and protocols. Further factors that exacerbate this variability in glycemic outcome are found to include measurement frequency and whether a protocol is blind to carbohydrate administration.