The impact of susceptibility gradients on cartesian and spiral EPI for BOLD fMRI

High sensitivity to magnetic susceptibility changes and accurate localization of functional activations are key requisites for pulse sequences used for BOLD fMRI. This paper seeks to develop a framework for analysing the performance of various k-space sampling techniques in this respect, with special emphasis on spiral EPI (spiral) and cartesian EPI (EPI) and their performance under influence of induced field gradients (SFGs) and stochastic noise. A numerical method for calculating synthetic MR images is developed and used to simulate BOLD fMRI experiments using EPI and spirals. The data is then examined for activation using a pixel-wise t test. Nine subjects are scanned with both techniques while performing a motor task. SPM99 is used for analysing the experimental data. The simulated spirals provide generally higher t scores at low SFGs but lose more strength than EPI at higher SFGs, where EPI activation is offset from the true position. In the primary motor area spirals provide significantly higher t scores (P < 0.0002). In-plane variation of EPI is higher in phase-encoding direction than in frequency-encoding direction (P < 0.003). In the low SFG areas spirals provide stronger activation than EPI and less spatial variability. Thus, spirals are recommended for fMRI in motor area and language areas.     

Enhanced incorporation of n−3 fatty acids from fish compared with fish oils

This work was undertaken to study the impact of the source of n−3 FA on their incorporation in serum, on blood lipid composition, and on cellular activation. A clinical trial comprising 71 volunteers, divided into five groups, was performed. Three groups were given 400 g smoked salmon (n=14), cooked salmon (n=15), or cooked cod (n=13) per week for 8 wk. A fourth group was given 15 mL/d of cod liver oil (CLO) (n=15), and a fifth group served as control (n=14) without supplementation. The serum content of EPA and DHA before and after intervention revealed a higher rise in EPA and DHA in the cooked salmon group (129% rise in EPA and 45% rise in DHA) as compared with CLO (106 and 25%, respectively) despite an intake of EPA and DHA in the CLO group of 3.0 g/d compared with 1.2 g/d in the cooked salmon group. No significant changes were observed in blood lipids, fibrinogen, fibrinolysis, or lipopolysaccharide (LPS)-induced tissue factor (TF) activity, tumor necrosis factor-α (TNFα), interleukin-8 (IL-8), leukotriene B₄ (LTB₄), and thromboxane B₂ (TxB₂) in whole blood. EPA and DHA were negatively correlated with LPS-induced TNFα, IL-8, LTB₄, TxB₂, and TF in whole blood. In conclusion, fish consumption is more effective in increasing serum EPA and DHA than supplementing the diet with fish oil. Since the n−3 FA are predominantly in TAG in fish as well as CLO, it is suggested that the larger uptake from fish than CLO is due to differences in physiochemical structure of the lipids.     

Effects of fasting prior to slaughter on pH development and energy metabolism post-mortem in M. longissimus dorsi of pigs

The aim of this study was to investigate the effect of pre-slaughter fasting time, sex and feeding regime on the development of energy metabolism and pH in M. longissimus dorsi (LD) post-mortem in pigs. Two hundred and seventy pigs of the commercial Norwegian crossbreed Noroc (LYLD) were used involving two sexes (gilts and castrates), two feeding regimes (restricted and ad libitum) and four different fasting treatments: (F4) 4 h fasting, (F175) 17.5 h fasting on the farm, (FO175) 17.5 h fasting overnight at the abattoir, and (FO265) 26.5 h fasting overnight at the abattoir. Additionally the pigs experienced two different abattoir lairage times as fasting treatment F4 and F175 had a lairage time of 1.5 h, while fasting treatment FO175 and FO265 had a lairage time of 23.0 h. A short fasting time of 4 h led to a delayed degradation of glycogen, slow decline in pH and a lower ultimate pH_{45 h} post-mortem (pHu) in the LD compared with a fasting time of 26.5 h which resulted in a rapid breakdown of glycogen and pH decline early post-mortem and a high pHu. Proglycogen was degraded in favour of macroglycogen under anaerobic conditions post-mortem. Feeding the animals in the morning before delivery if slaughtered the same day, results in low pH reduction rate and a low pHu compared with pigs fasted overnight either on farm or at the abattoir. Aiming a higher pHu in LD it should be recommended not to feed the pigs in the morning at the day of slaughter.     

Use of reliability technology in the process industry

Reliability analysis has been established as a useful tool for risk analysis and the design of safety systems. During the past ten years use of advanced methods for optimal maintenance and process control based on reliability technology has been introduced. Lack of data has been a problem, but even more important has been the reluctance of personnel involved with regard to implementation of these methods. One reason for this is the complexity of the models and methods presented. In the future more emphasis should be put on the solving of problems as experienced by the industry. The following are proposed to encourage the use of reliability technology:

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  close cooperation with industry;

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  focus on specific problems as experienced by the industry rather than system modelling;

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  development of simple methods to be applied by the people who own the problem.

     

Reactive power and voltage control based on general quantum genetic algorithms

This paper presents an improved evolutionary algorithm based on quantum computing for optimal steady-state performance of power systems. However, the proposed general quantum genetic algorithm (GQ-GA) can be applied in various combinatorial optimization problems. In this study the GQ-GA determines the optimal settings of control variables, such as generator voltages, transformer taps and shunt VAR compensation devices for optimal reactive power and voltage control of IEEE 30-bus and 118-bus systems. The results of GQ-GA are compared with those given by the state-of-the-art evolutionary computational techniques such as enhanced GA, multi-objective evolutionary algorithm and particle swarm optimization algorithms, as well as the classical primal-dual interior-point optimal power flow algorithm. The comparison demonstrates the ability of the GQ-GA in reaching more optimal solutions.     

Using mobile code to build a smart kitchen

Software infrastructures for handheld and ubiquitous computing systems help developers tackle many implementation problems. Sun Microsystems recently introduced an infrastructure called Jini. We report on our experiences of using Jini to build a smart kitchen. We found that the central Jini concept of code mobility proved very beneficial offering a simple mechanism for device interoperability and encouraging developers to better structure the software.     

Handling nonconforming individuals in search-based model-driven engineering: nine generic strategies for feature location in the modeling space of the meta-object facility

Software and Systems Modeling - Lately, the model-driven engineering community has been paying more attention to the techniques offered by the search-based software engineering community. However,...     

Multilevel least squares approximation of scattered data over binary triangulations

An adaptive method for approximating huge scattered data sets is presented. The approximation scheme generates multilevel triangulations obtained using a subdivision scheme known as longest edge bisection. Nested function spaces are defined over the multilevel triangulations. The approximation problem is solved by successive refinement of the triangulation while iterative methods are used for solving a system of linear equations at intermediate levels of the multi-level scheme. Regularization terms are coupled with a standard least squares formulation to guarantee uniqueness and control smoothness of the solution. Communicated by: G. Wittum     

Modelling and quality assessment of spots in digital images — With application to DNA microarrays

Based on a recently developed spot segmentation method, we here present a new approach to modelling of individual spots in digital images, e.g. images of DNA microarrays. From the model parameter estimates and residuals we have developed an expedient approach to automatic quality assessment and identification of corrupted spots. The suggested approach to quality control is shown to give a statistically significant decrease of the variance in gene expression log-ratio estimates for three different DNA microarray datasets.     

Diffusion potentials as source of error in electrochemical measurements in concrete

Condition assessment or controlling systems for cathodic protection of reinforced concrete structures are usually based on potential measurements. In case of permanent monitoring systems, reference electrodes are embedded in the concrete, whereas for occasional investigations external reference electrodes are normally used and placed on the concrete surface. However, ionic concentration gradients between the inner solution of the reference electrode and the concrete pore solution give rise to liquid junction potentials. In addition, internal gradients in pH or chloride content, as well as permselective properties of the cement paste lead to membrane potentials. Although these phenomena are usually not considered to be significant, they might be underestimated in many cases and lead to misinterpretation of measurement results. This is especially important with regard to applications of potentiometric sensors such as chloride or pH sensors, where accurate potential readings are fundamental. This article presents the theoretical background and summarises available literature with regard to diffusion potentials in concrete. Liquid junction potentials between various solutions have been measured experimentally. Practical consequences and possible attempts to minimise measurement errors are discussed.