Interactive creative problem solving

A set creative problem‐solving tools for instructional purposes is discussed. The tools include a problem‐solving text which presents the heuristic, a set of slides in electronic form that can be used to enhance classroom presentations, and interactive computer modules that reinforce and develop the students' problem‐solving skills. © 1996 John Wiley & Sons, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110731/1/4_ftp.pd

Dissolution of powdered minerals: The effect of polydispersity

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37407/1/690350520_ftp.pd

The role of conduction/valence bands and redox potential in accelerated mineral dissolution

The dissolution kinetics of a number of manganese oxides in acidic solutions were studied. Using a slurry reactor, rate laws were determined for each of the manganese oxides in the hydrohalogen acids. Significant variations in the reaction rates (up to five orders of magnitude over the HCl base rate) were obtained with different acids. The addition of anions as neutral salts to acidic solutions is shown to produce the same rate-accelerating effect as acids containing that anion. The effect of the different acids on the oxide dissolution rates is explained using semiconductor band theory and energy diagrams.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37394/1/690321013_ftp.pd

Promoter–enhancer looping at the PPARγ2 locus during adipogenic differentiation requires the Prmt5 methyltransferase

PPARγ2 is a critical lineage-determining transcription factor that is essential for adipogenic differentiation. Here we report characterization of the three-dimensional structure of the PPARγ2 locus after the onset of adipogenic differentiation and the mechanisms by which it forms. We identified a differentiation-dependent loop between the PPARγ2 promoter and an enhancer sequence 10 kb upstream that forms at the onset of PPARγ2 expression. The arginine methyltransferase Prmt5 was required for loop formation, and overexpression of Prmt5 resulted in premature loop formation and earlier onset of PPARγ2 expression. Kinetic studies of regulatory factor interactions at the PPARγ2 promoter and enhancer revealed enhanced interaction of Prmt5 with the promoter that preceded stable association of Prmt5 with enhancer sequences. Prmt5 knockdown prevented binding of both MED1, a subunit of Mediator complex that facilitates enhancer–promoter interactions, and Brg1, the ATPase of the mammalian SWI/SNF chromatin remodeling enzyme required for PPARγ2 activation and adipogenic differentiation. The data indicate a dynamic association of Prmt5 with the regulatory sequences of the PPARγ2 gene that facilitates differentiation-dependent, three-dimensional organization of the locus. In addition, other differentiation-specific, long-range chromatin interactions showed Prmt5-dependence, indicating a more general role for Prmt5 in mediating higher-order chromatin connections in differentiating adipocytes.National Institutes of Health (NIH) [DK084278 to S.S., A.N.I., GM56244 to A.N.I., F32DK082263 to S.E.L., DK32520 to UMass Medical School Diabetes and Endocrine Research Center]. Funding for open access charge: Institutional funds

Population balance modeling of the dissolution of polydisperse solids: Rate limiting regimes

Significant errors can result in modeling dissolution processes if the polydispersity of the solid particles is ignored and the sample is treated as a collection of monodisperse spheres having the average size of the mixture. Population balance modeling provides an effective analytical means of predicting the effect of polydispersity on a wide variety of heterogeneous reaction systems including dissolution processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37395/1/690330108_ftp.pd

ATXR5 and ATXR6 are H3K27 monomethyltransferases required for chromatin structure and gene silencing.

Constitutive heterochromatin in Arabidopsis thaliana is marked by repressive chromatin modifications, including DNA methylation, histone H3 dimethylation at Lys9 (H3K9me2) and monomethylation at Lys27 (H3K27me1). The enzymes catalyzing DNA methylation and H3K9me2 have been identified; alterations in these proteins lead to reactivation of silenced heterochromatic elements. The enzymes responsible for heterochromatic H3K27me1, in contrast, remain unknown. Here we show that the divergent SET-domain proteins ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6 have H3K27 monomethyltransferase activity, and atxr5 atxr6 double mutants have reduced H3K27me1 in vivo and show partial heterochromatin decondensation. Mutations in atxr5 and atxr6 also lead to transcriptional activation of repressed heterochromatic elements. Notably, H3K9me2 and DNA methylation are unaffected in double mutants. These results indicate that ATXR5 and ATXR6 form a new class of H3K27 methyltransferases and that H3K27me1 represents a previously uncharacterized pathway required for transcriptional repression in Arabidopsis

Alendronate and Resistive Exercise Countermeasures Against Bed Rest-Induced Bone Loss: Biochemical Markers of Bone and Calcium Metabolism

Weightlessness-induced bone loss must be counteracted to ensure crew health during extendedduration space missions. Studies were conducted to assess two bone loss countermeasures in a ground-based model: horizontal bed rest. Following a 3-wk ambulatory adaptation period, male and female subjects (aged 21-56 y) completed a 17-wk bed rest protocol. Subjects were assigned to one of three treatments: alendronate (ALEN; 10 mg/d, n=6), resistive exercise (RE; 1.5 h/d, 6 d/wk, n=8), or control (CN; no countermeasure, n=8). Dietary intake was adjusted to maintain body weight. Endocrine and biochemical indices were measured in blood and urine using standard laboratory methods. All data reported are expressed as percent change from individual pre-bedrest data. Serum calcium changed little during bed rest, and tended to decrease (4-8%) in ALEN subjects. In RE subjects, bone alkaline phosphatase and osteocalcin were increased >65 and >30%, respectively, during bed rest, while these were unchanged or decreased in ALEN and CN subjects. Urinary calcium was increased 50% in CN subjects, but was unchanged or decreased in both ALEN and RE groups. Urinary n-telopeptide excretion was increased 40-50% in CN and RE subjects, but decreased 20% in ALEN subjects. Pyridinium crosslink and deoxypyridinoline excretion were increased 20-50% during bed rest. These data suggest that RE countermeasures are effective at increasing markers of bone formation in an analog of weightlessness, while ALEN reduces markers of bone resorption. Counteracting the bone loss of space flight may require both pharmacologic and exercise countermeasures

Using naturalistic driving data to assess variations in fuel efficiency among individual drivers

Fuel consumption rates were studied from a naturalistic driving data set employing a fleet of identical passenger vehicles with gasoline engines and automatic transmissions. One hundred and seventeen drivers traveled a total of over 342,000 kilometers (213,000 miles), unsupervised, using one of the experiment’s instrumented test vehicles as their own. Continuous monitoring of hundreds of data signals, including fuel flow rate, provides a unique data set of driving behavior with a common vehicle. The results are presented for both the overall fuel consumption as well as fuel consumption for speedkeeping and accelerating-from-rest events. A substantial variation in the overall fuel consumption rate was observed. The differences between the mean consumption rate and the fuel consumption rates for the 10th and 90th percentile drivers were 13 and 16 percent, respectively, of the mean value. The corresponding differences between the 10th and 90th percentiles and the mean for both speed-keeping events and accelerating-from-rest events were up to 10 percent. While some of the obtained variation in fuel economy is likely due to uncontrolled or unmeasured factors, such as passenger and fuel weight, and wind, the data imply that the behavior of real-world drivers adds significant variation to fuel consumption rates. The present findings suggest the possibility of substantial potential gains in real-world efficiencies through modification of driver behavior itself (e.g., through training), or for electronic modulation technology between the driver’s foot and the throttle to modify a relatively wasteful driver into a more efficient one.The University of Michigan Sustainable Worldwide Transportationhttp://deepblue.lib.umich.edu/bitstream/2027.42/78449/1/102705.pd

The PPARgamma locus makes long-range chromatin interactions with selected tissue-specific gene loci during adipocyte differentiation in a protein kinase A dependent manner

Differentiation signaling results in reprogramming of cellular gene expression that leads to morphological changes and functional specialization of a precursor cell. This global change in gene expression involves temporal regulation of differentiation-specific genes that are located throughout the genome, raising the idea that genome structure may also be re-organized during cell differentiation to facilitate regulated gene expression. Using in vitro adipocyte differentiation as a model, we explored whether gene organization within the nucleus is altered upon exposure of precursor cells to signaling molecules that induce adipogenesis. The peroxisome proliferator-activated receptor gamma (PPARgamma) nuclear hormone receptor is a master determinant of adipogenesis and is required for adipose differentiation. We utilized the chromosome conformation capture (3C) assay to determine whether the position of the PPARgamma locus relative to other adipogenic genes is changed during differentiation. We report that the PPARgamma2 promoter is transiently positioned in proximity to the promoters of genes encoding adipokines and lipid droplet associated proteins at 6 hours post-differentiation, a time that precedes expression of any of these genes. In contrast, the PPARgamma2 promoter was not in proximity to the EF1alpha promoter, which drives expression of a constitutively active, housekeeping gene that encodes a translation elongation factor, nor was the PPARgamma2 promoter in proximity to the promoter driving the expression of the C/EBPalpha regulatory protein. The formation of the long-range, intergenic interactions involving the PPARgamma2 promoter required the regulatory factor C/EBPbeta, elevated cyclic AMP (cAMP) levels, and protein kinase A (PKA) signaling. We conclude that genome organization is dynamically remodeled in response to adipogenic signaling, and we speculate that these transient inter-genic interactions may be formed for the purposes of selecting some of the transcriptionally silent tissue-specific loci for subsequent transcriptional activation