Accelerating multi-echo water-fat MRI with a joint locally low-rank and spatial sparsity-promoting reconstruction

Objectives

Our aim was to demonstrate the benefits of using locally low-rank (LLR) regularization for the compressed sensing reconstruction of highly-accelerated quantitative water-fat MRI, and to validate fat fraction (FF) and \({R_2^*}\) relaxation against reference parallel imaging in the abdomen.

Materials and methods

Reconstructions using spatial sparsity regularization (SSR) were compared to reconstructions with LLR and the combination of both (LLR+SSR) for up to seven fold accelerated 3-D bipolar multi-echo GRE imaging. For ten volunteers, the agreement with the reference was assessed in FF and \({R_2^*}\) maps.

Results

LLR regularization showed superior noise and artifact suppression compared to reconstructions using SSR. Remaining residual artifacts were further reduced in combination with SSR. Correlation with the reference was excellent for FF with \(R^2\) = 0.99 (all methods) and good for \({R_2^*}\) with \(R^2\) = [0.93, 0.96, 0.95] for SSR, LLR and LLR+SSR. The linear regression gave slope and bias (%) of (0.99, 0.50), (1.01, 0.19) and (1.01, 0.10), and the hepatic FF/\({R_2^*}\) standard deviation was 3.5%/12.1 s\(^{-1}\), 1.9%/6.4 s\(^{-1}\) and 1.8%/6.3 s\(^{-1}\) for SSR, LLR and LLR+SSR, indicating the least bias and highest SNR for LLR+SSR.

Conclusion

A novel reconstruction using both spatial and spectral regularization allows obtaining accurate FF and \({R_2^*}\) maps for prospectively highly accelerated acquisitions.

     

Natural variability in lake pH on seasonal, interannual and decadal time scales: implications for assessment of human impact

Reference values define the natural state with respect to environmental stressors and are commonly used for assessments of ecological impacts and to set restoration targets. These reference values are often treated as constants, whereas in reality they can be highly variable. Here, we study the significance of this variability for assessments of human impact on the environment, by using almost two decades of observations from 95 acid-sensitive Swedish lakes. Our approach was to first estimate the preindustrial, steady-state reference level of acid neutralization capacity (ANC) for each lake with the hydrogeochemical model MAGIC. Then the variability in pH around this "baseline" was reconstructed from the contemporary, "natural" variability in the ANC, total organic carbon (TOC) and Al-concentrations, and partial CO2 pressure. The variability in reference pH was then examined for the period 1990-2004, on seasonal (single measurements), interannual (1-year median), and decadal (5-year median) scales. On the seasonal scale, the variability in reference pH ranged between 0.40 and 1.7. The range on the interannual time scale was up to 1.3 units and for the decadal scale up to 0.76 units. Since an anthropogenic pH decline of more than 0.4 units is deemed significant according to the Swedish Environmental Quality Criteria, this natural variability clearly needs to be accounted for when assessing acidification.     

Managing Surface Water Contamination in Nagoya, Japan: An Integrated Water Basin Management Decision Framework

The water quality of rivers in Japan has received greater attention in recent years due to a number of factors, including human-induced land subsidence and an increase in water demand. Surface waters are adversely affected by high frequency, low level risks (such as the continuous release of hazardous substances) and less frequent, high impact risks (such as the release of chemicals due to natural disasters or industrial accidents). This paper puts forth an integrated Water Basin Management (WBM) decision framework to study the latter: these relatively infrequent, but often catastrophic hazards, are less well-studied than the more familiar high frequency, low level risks. The six main components of this WBM decision framework involve (a) determining possible threats to surface waters; (b) identifying surface waters most at risk to contamination; (c) identifying weaknesses (gaps) in current monitoring systems; (d) using accident analysis to determine proactive WBM; (e) analyzing the temporal-spatial impact of policies on water basins, (f) designing new policies and approaches for integrated WBM. Japan's recently published Pollutant Release and Transfer Register (PRTR) is used to develop a WBM decision framework for managing surface water contamination in Nagoya, Japan. Participatory surface water management is emphasized in order to achieve a holistic and sustainable WBM decision making process.     

Mass spectrometric evidence for a zinc-porphyrin complex as the red pigment in dry-cured Iberian and Parma ham

Extracts containing red pigment complexes from the two types of dry-cured hams, Italian Parma and Spanish Iberian ham, were obtained using water and acetone as extraction solvents followed by a crude purification with C18 column filtration. The purified extracts were then analyzed spectroscopically by recording absorption and fluorescence spectra (λ(ex)=420nm), which both indicate the presence of chemically identical red chromophores with properties similar to a complex of transition metals and protoporphyrin IX. Electrospray ionization mass spectrometry (ESI-MS) in the positive ion mode confirms the presence of identical chemical compounds. ESI-MS in the negative ion mode detects a cluster of seven isotopologue ions (that of m/z 623.2 as the most intense) with a pattern matching that of a Zn protoporphyrin IX complex. Based on mass spectral data it is concluded that a Zn-porphyrin complex constitutes a major chromophore in dry-cured Iberian ham as well as in Parma ham.     

Reliability of thermal interface materials: A review

Thermal interface materials (TIMs) are used extensively to improve thermal conduction across two mating parts. They are particularly crucial in electronics thermal management since excessive junction-to-ambient thermal resistances can cause elevated temperatures which can negatively influence device performance and reliability. Of particular interest to electronic package designers is the thermal resistance of the TIM layer at the end of its design life. Estimations of this allow the package to be designed to perform adequately over its entire useful life. To this end, TIM reliability studies have been performed using accelerated stress tests. This paper reviews the body of work which has been performed on TIM reliability. It focuses on the various test methodologies with commentary on the results which have been obtained for the different TIM materials. Based on the information available in the open literature, a test procedure is proposed for TIM selection based on beginning and end of life performance.     

Effects of Fusarium infection on the amino acid composition of winter wheat grain

Winter wheat (susceptible cultivar Ritmo) was grown in 2006 near Kiel and in 2007 near Heide in northern Germany. Plants were inoculated at anthesis using a Fusarium graminearum macroconidial suspension. The percentage of Fusarium-damaged kernels (FDK) ranged from 0 ± 2% to 28 ± 2%. The contents of the Fusarium mycotoxin deoxynivalenol (DON) and wheat amino acids were determined in the grain. Levels of the amino acids alanine, lysine, and tyrosine increased with the percentage of FDK or DON contents whereas glutamic acid contents decreased. Aspartic acid and threonine were not related to the percentage of FDK or DON contents. Effects of Fusarium infection on other amino acids were significant only at the sampling site with the higher degree of Fusarium-damage. Interestingly, those amino acids that increased consistently and significantly with the degree of Fusarium-damage are derived from phosphoenolpyruvate or pyruvate, suggesting that pathogen-induced changes in the glycolytic input for amino acid biosynthesis play a significant role for the amino acid composition of Fusarium-damaged winter wheat grain. On average, amino acid contents decreased by 0.13% compared to the amino acid content of sound kernels upon an increase of 1% of FDK.     

Development and test of small-scale batch-fired straw boilers in Denmark

In Denmark, government subsidies for the testing and installation of biomass-fired boilers were available for the period from 1995 until 2002. Each boiler type had to pass an official approval test to achieve subsidy. The combustion abilities of the boiler were optimized prior to the test. The main aim of this subsidy was to encourage the development of energy-efficient and environmentally friendly boilers. The scheme was therefore organized in such a way that the greatest subsidies were awarded for boilers with high efficiency and low emissions. This goal has in effect been achieved for batch-fired straw boilers, where the typical efficiency has been increased from about 75% in 1995 to about 87% in 2002. Similarly, the carbon monoxide emissions have been reduced from 5000 ppm (reference value 10% O₂) in 1995 to less than 1000 ppm in 2002. These improvements are mainly due to better insulation inside the combustion chamber, more efficient techniques for supplying air to the combustion process, improved cooling of the flue gas, and optimization of the electronic control unit for the air supply.     

Multi-access Management in Heterogeneous Networks

Communication networks and mobile devices integrate an increasing number of access technologies. At the same time, new business roles emerge, which lead to new cooperation schemes between access providers providing different types of access connectivity. As a result, a variety of access technologies will be available for users at the same time. In this article we present an architecture and a framework capable of integrating different access systems into a multi-access system and selecting the best suited access for users. A utility-based approach is proposed for the evaluation of different access allocation choices, which is based on user and network policies, the performance of access bearers, and the availability of access resources. We present a general multi-access management framework, which integrates the different multi-access related functions: access detection, access evaluation and access selection, which can then lead to an access handover.

脉冲骚扰测量的新型CISPR加权方式——CRMS检波器和APD测量功能

为了更好地分析现代数字无线通讯中的脉冲骚扰,在CISPR 16-1-1中新发布了两种加权方式：均方根值-平均值（CRMS）检波器和幅度概率分布（APD）测量方式.介绍了新的检波器和测量方式的目的、定义和特性评估,以及在标准中的应用.