A supervised clustering approach for fMRI-based inference of brain states

We propose a method that combines signals from many brain regions observed in functional Magnetic Resonance Imaging (fMRI) to predict the subject's behavior during a scanning session. Such predictions suffer from the huge number of brain regions sampled on the voxel grid of standard fMRI data sets: the curse of dimensionality. Dimensionality reduction is thus needed, but it is often performed using a univariate feature selection procedure, that handles neither the spatial structure of the images, nor the multivariate nature of the signal. By introducing a hierarchical clustering of the brain volume that incorporates connectivity constraints, we reduce the span of the possible spatial configurations to a single tree of nested regions tailored to the signal. We then prune the tree in a supervised setting, hence the name supervised clustering, in order to extract a parcellation (division of the volume) such that parcel-based signal averages best predict the target information. Dimensionality reduction is thus achieved by feature agglomeration, and the constructed features now provide a multi-scale representation of the signal. Comparisons with reference methods on both simulated and real data show that our approach yields higher prediction accuracy than standard voxel-based approaches. Moreover, the method infers an explicit weighting of the regions involved in the regression or classification task.     

Lipids of maturing grain of corn (Zea mays L.):

The polar lipids of a standard corn inbred, H51, were analyzed as the kernels developed. The concentrations of the glycolipids and phospholipids were highest at 30–45 days after pollination and then decreased. Digalactosyl diglyceride was the dominant glycolipid in the maturing grain. Monogalactosyl diglyceride and sulfolipid were also major sugar-containing lipids, but steryl glycoside ester, steryl glycoside and cerebrosides were relatively minor components. Phosphatidyl choline accounted for over 50% of the total phosphorus of the phospholipids at all stages of kernel development. Phosphatidyl ethanolamine and phosphatidyl inositol ranked second and third. Each individual lipid had its own characteristic fatty acid pattern, but the changes in fatty acid composition during development of the corn kernels were similar for all the lipids. The percentages of palmitic acid and linolenic acid decreased while those of oleic acid increased. Contribution from the Department of Agronomy, University of Illinois, and Crops Research Division, ARS, USDA.     

Profile of nutritional risk in pregnant adolescents

A sample of 215 adolescents (16.9 +/- 0.7 y; 13-18 y) from a low socioeconomic level of Valencia, Venezuela, at their first trimester of pregnancy were studied in order to identify nutritional risk. Socioeconomic, anthropometrical, hematological and dietary characteristic were assessed. Pregestational weight, actual weight, height, arm circumference (AC), triceps skin fold (TS), fat and muscle area (FA/MA) and pregestational body mass index (PBMI) were determined. Hemoglobin (Hb) and ferritin were measured by colorimetric and ELISA methods. Two 24 hour recalls were obtained. According to age, two groups were created. Pregnant adolescents were grouped by age: Group 1, 13 to 15 years old and Group 2, 16 to 18 years old. Nutritional risk was defined as: Gynecological age lower than 4 years since menarche. PBMI < 19.8 kg/m2, height below 10th Percentile of reference, Hb below 11 g/dL and ferritin < 12 micrograms/L. Almost all the adolescents (96.3%) were in poverty. 83.3% were single, 83.3% were at elementary school before pregnancy but 84.1% were attending house chores at the time of exam. There were significant differences (p < 0.001) for gynecological age and menarche age, but not for anthropometrical, hematological and dietary variables when Group 1 was compared to group 2. 35.3% of the adolescents had a gynecological age lower than 4 years, 23.3% were below 10th percentile for height, 36.3% had a PBMI lower than 19.8 kg/m2, 26.5% were below 10th percentile for arm circumference, anemia was present in 13.7% and low levels of ferritin in 18.4% of the adolescents. Calorie intake was below recommendation in 87.3% and adequacy for vitamin A and C, calcium and zinc were below 2/3 of recommendation in 36.3%. 25.9%, 88.7% and 73.5% of the adolescents respectively. Studied adolescents had a high prevalence of risk factors for nutritional deficiencies (short age, poverty, low weight, anemia and deficient intake). Early assessment of this conditions allows to identify the risk, to establish interventions and to monitor pregnancy evolution.     

Spectral fluorometric characterization of phytoplankton community composition using the Algae Online Analyser

The utility of a multiple-fixed-wavelength spectral fluorometer, the Algae Online Analyser (AOA), as a means of quantifying phytoplankton biomass and community composition was tested using natural communities from two southeastern United States estuaries, North Inlet, South Carolina, and the Neuse River Estuary, North Carolina. Estimates of biomass (as chlorophyll a) were correlated with HPLC values and variations (usually over-estimates) were consistent with effects of light intensity and nutrient availability on fluorescence quenching. AOA estimates of taxonomic structure were consistent with those from HPLC-derived marker pigments by ChemTax, with both methods indicating domination by chromophytes and green algae in North Inlet and chromophytes and cyanobacteria in the Neuse. We recommend frequent calibration by discrete sample collection, and calibration with species representative of the region of interest. Overall, the AOA appears to be a useful tool for monitoring of phytoplankton community composition, especially as an early warning system for the detection of harmful algal blooms.     

Hybrid threshold optimization between global image and local regions in image segmentation for melasma severity assessment

Melasma image segmentation plays a fundamental role for computerized melasma severity assessment. A method of hybrid threshold optimization between a given image and its local regions is proposed and used for melasma image segmentation. An analytic optimal hybrid threshold solution is obtained by minimizing the deviation between the given image and its segmented outcome. This optimal hybrid threshold comprises both local and global information around image pixels and is used to develop an optimal hybrid thresholding segmentation method. The developed method is firstly evaluated based on synthetic images and subsequently used for melasma segmentation and severity assessment. Statistical evaluations of experimental results based on real-world melasma images show that the proposed method outperforms other state-of-the-art thresholding segmentation methods for melasma severity assessment.     

Phase change phenomena in silicon microchannels

Understanding the boiling process and two-phase flow behavior in microchannels is the key to developing microchannel heat sinks for high-power microprocessors. We conducted experiments in micromachined silicon channels with a range of 27-171 μm hydraulic diameters and varying surface roughnesses. Bubble nucleation, flow patterns, wall temperature, as well as transient pressure fluctuations were recorded and analyzed. We observed both typical nucleate boiling and eruption boiling with large amounts of wall superheat in these channels, and recorded up to 138 kPa transient pressure fluctuations due to bubble nucleation. We found the boiling mechanism is strongly dependent on the wall surface roughness, and we explained the boiling mechanism in sub-150 μm diameter channels with Hsu’s model.     

Evaporation Cooling Using a Bionic Micro Porous Evaporation System

The temperature increase due to incident solar radiation has an adverse impact on the electrical output of photovoltaic (PV) modules. A theoretical model of the fabricated and tested bionic evaporation backside cooling was established and verified by experimental investigation. A microfluidic structure featuring micropores consists of two polymer layers attached on the backside of a PV cell model. The thermal performance of roof-mounted PV modules with rear panel air ventilation was mathematically described and extended by the cooling capabilities of the developed bionic evaporation foil. The results of experimental investigations performed in a roof equivalent test environment consisting of a wind tunnel within a climate chamber are in good accordance to the established model. Experimentally, temperature reductions at low incident solar power of less than 575 W causing an efficiency gain for up to 4.8% have been demonstrated while the model implicates an efficiency increase of 10% for real roof systems at an incident solar radiation of 1000 W.     

Effect pigments for textile coating: a review of the broad range of advantageous functionalization

The presented review will introduce the use of effect pigments as a powerful tool for the functionalization of textiles. This review starts with a short introduction on the basics of effect pigments and their properties. Subsequently, some principles of effect pigment application onto textiles and the interaction of pigment to binder systems are reported. Different possible functionalizations realized on textiles are presented. Four main types of application are discussed: optical properties, electrical properties, barrier coatings, and antimicrobial applications. Also a view of some prospective anisotropic materials is given. Altogether it is shown that the application of effect pigments can be a powerful tool to realize functional textiles for a broad range of applications in different fields.     

Comparison between the design of experiments and simulation in the three-phase distillation in a sieve tray column for glycerine dehydration

Design of experiments (DOE) is a value scientific approach used to understand the processes in a better way and to determine how the inputs affect the response(s). In this work, this method has been applied to study the behavior of the three-phase distillation in a sieve tray column, through the effects of the process and geometrical variables. The experimental values were compared with predicted values obtained by simulation using the equilibrium and nonequilibrium models. Three-phase distillation has been used for glycerine dehydration using toluene as entrainer, in order to avoid the glycerol degradation by distillation at atmospheric pressure. The best conditions found were: vapor flow rate of toluene = 23.5 kg/h, feed flow rate = 2.2 kg/h and feed concentration = 50 wt% glycerol, using the layout L₄ with fractional hole area = 0.04 and weir height = 70 mm. The nonequilibrium model based on Eckert and Vanek's approach (2001) and Chen–Chuang's correlation (1993) have been used to estimate the binary coefficients of mass transport. The predicted values obtained by the experimental model and by the nonequilibrium model have represented the behavior of the dehydration in the sieve tray column studied. Both models underpinned the experimental results obtained for this column.     

Engineered Bacterial Flavin-Dependent Monooxygenases for the Regiospecific Hydroxylation of Polycyclic Phenols

4-Hydroxyphenylacetate 3-hydroxylase (4HPA3H), a flavin-dependent monooxygenase from E. coli that catalyzes the hydroxylation of monophenols to catechols, was modified by rational redesign to convert also more bulky substrates, especially phenolic natural products like phenylpropanoids, flavones or coumarins. Selected amino acid positions in the binding pocket of 4HPA3H were exchanged with residues from the homologous protein from Pseudomonas aeruginosa, yielding variants with improved conversion of spacious substrates such as the flavonoid naringenin or the alkaloid mimetic 2-hydroxycarbazole. Reactions were followed by an adapted Fe(III)-catechol chromogenic assay selective for the products. Especially substitution of the residue Y301 facilitated modulation of substrate specificity: introduction of nonaromatic but hydrophobic (iso)leucine resulted in the preference of the substrate ferulic acid (having a guaiacyl (guajacyl) moiety, part of the vanilloid motif) over unsubstituted monophenols. The in vivo (whole-cell biocatalysts) and in vitro (three-enzyme cascade) transformations of substrates by 4HPA3H and its optimized variants was strictly regiospecific and proceeded without generation of byproducts.