1,311 research outputs found
The application of Riegels' rule and time-like damping to transonic flow calculations
Finite difference relaxation solutions of the nonlinear small perturbation equations have proven reliable and successful in determining the transonic flowfields about thin airfoils. However, application of the small perturbation approach to thick airfoils usually results in an accuracy less than desirable. The incorporation of Riegels' Rule and time-like damping into the small perturbation approach and their application to thick and thin airfoils in transonic flow are discussed. Studies for thick and thin airfoils are presented. It is concluded that Riegels' Rule and damping should both be included in small perturbation transonic flow calculations
Can modeling and simulation really help power system designers?
The rap session provided an informal forum for dissemination of information on the state of the art in modeling and simulation of power processing systems. Merits of time domain and frequency domain approaches were debated and the use of these techniques for the prediction of performance and the optimization of a design were discussed. Although it appears that the present state of the art is somethat primative, interest is high and continued progress and improvement should be forthcoming
Tumor site immune markers associated with risk for subsequent basal cell carcinomas.
BackgroundBasal cell carcinoma (BCC) tumors are the most common skin cancer and are highly immunogenic.ObjectiveThe goal of this study was to assess how immune-cell related gene expression in an initial BCC tumor biopsy was related to the appearance of subsequent BCC tumors.Materials and methodsLevels of mRNA for CD3Δ (a T-cell receptor marker), CD25 (the alpha chain of the interleukin (IL)-2 receptor expressed on activated T-cells and B-cells), CD68 (a marker for monocytes/macrophages), the cell surface glycoprotein intercellular adhesion molecule-1 (ICAM-1), the cytokine interferon-Îł (IFN-Îł) and the anti-inflammatory cytokine IL-10 were measured in BCC tumor biopsies from 138 patients using real-time PCR.ResultsThe median follow-up was 26.6 months, and 61% of subjects were free of new BCCs two years post-initial biopsy. Patients with low CD3Δ CD25, CD68, and ICAM-1 mRNA levels had significantly shorter times before new tumors were detected (pâ=â0.03, pâ=â0.02, pâ=â0.003, and pâ=â0.08, respectively). Furthermore, older age diminished the association of mRNA levels with the appearance of subsequent tumors.ConclusionsOur results show that levels of CD3Δ, CD25, CD68, and ICAM-1 mRNA in BCC biopsies may predict risk for new BCC tumors
Comparative mitochondrial genomics of snakes: extraordinary substitution rate dynamics and functionality of the duplicate control region
<p>Abstract</p> <p>Background</p> <p>The mitochondrial genomes of snakes are characterized by an overall evolutionary rate that appears to be one of the most accelerated among vertebrates. They also possess other unusual features, including short tRNAs and other genes, and a duplicated control region that has been stably maintained since it originated more than 70 million years ago. Here, we provide a detailed analysis of evolutionary dynamics in snake mitochondrial genomes to better understand the basis of these extreme characteristics, and to explore the relationship between mitochondrial genome molecular evolution, genome architecture, and molecular function. We sequenced complete mitochondrial genomes from Slowinski's corn snake (<it>Pantherophis slowinskii</it>) and two cottonmouths (<it>Agkistrodon piscivorus</it>) to complement previously existing mitochondrial genomes, and to provide an improved comparative view of how genome architecture affects molecular evolution at contrasting levels of divergence.</p> <p>Results</p> <p>We present a Bayesian genetic approach that suggests that the duplicated control region can function as an additional origin of heavy strand replication. The two control regions also appear to have different intra-specific versus inter-specific evolutionary dynamics that may be associated with complex modes of concerted evolution. We find that different genomic regions have experienced substantial accelerated evolution along early branches in snakes, with different genes having experienced dramatic accelerations along specific branches. Some of these accelerations appear to coincide with, or subsequent to, the shortening of various mitochondrial genes and the duplication of the control region and flanking tRNAs.</p> <p>Conclusion</p> <p>Fluctuations in the strength and pattern of selection during snake evolution have had widely varying gene-specific effects on substitution rates, and these rate accelerations may have been functionally related to unusual changes in genomic architecture. The among-lineage and among-gene variation in rate dynamics observed in snakes is the most extreme thus far observed in animal genomes, and provides an important study system for further evaluating the biochemical and physiological basis of evolutionary pressures in vertebrate mitochondria.</p
The Co-occurrence of child and intimate partner maltreatment in the family: characteristics of the violent perpetrators
This study considers the characteristics associated with mothers and fathers who maltreat their child and each other in comparison to parents who only maltreat their child. One hundred and sixty-two parents who had allegations of child maltreatment made against them were considered. The sample consisted of 43 fathers (Paternal FamilyâPF) and 23 mothers (Maternal FamilyâMF) who perpetrated both partner and child maltreatment, together with 23 fathers (Paternal ChildâPC) and 26 mothers (Maternal ChildâMC) who perpetrated child maltreatment only. In addition, 2 fathers (Paternal VictimâPV) and 23 mothers (Maternal VictimâMV) were victims of intimate partner maltreatment and perpetrators of child maltreatment and 7 fathers (Paternal Non-abusive CarerâPNC) and 15 mothers (Maternal Non-abusive CarerâMNC) did not maltreat the child but lived with an individual who did. Within their family unit, 40.7% of parents perpetrated both intimate partner and child maltreatment. However, fathers were significantly more likely to maltreat both their partner and child than mothers and mothers were significantly more likely to be victims of intimate partner violence than fathers. PF fathers conducted the highest amount of physical and/or sexual child maltreatment while MC and MV mothers perpetrated the highest amount of child neglect. Few significant differences between mothers were found. PF fathers had significantly more factors associated with development of a criminogenic lifestyle than PC fathers. Marked sex differences were demonstrated with PF fathers demonstrating significantly more antisocial characteristics, less mental health problems and fewer feelings of isolation than MF mothers. MC mothers had significantly more childhood abuse, mental health problems, parenting risk factors and were significantly more likely to be biologically related to the child than PC fathers. This study suggests that violent families should be assessed and treated in a holistic manner, considering the effects of partner violence upon all family members, rather than exclusively intervening with the violent man
Functional Properties of Human Auditory Cortical Fields
While auditory cortex in non-human primates has been subdivided into multiple functionally specialized auditory cortical fields (ACFs), the boundaries and functional specialization of human ACFs have not been defined. In the current study, we evaluated whether a widely accepted primate model of auditory cortex could explain regional tuning properties of fMRI activations on the cortical surface to attended and non-attended tones of different frequency, location, and intensity. The limits of auditory cortex were defined by voxels that showed significant activations to non-attended sounds. Three centrally located fields with mirror-symmetric tonotopic organization were identified and assigned to the three core fields of the primate model while surrounding activations were assigned to belt fields following procedures similar to those used in macaque fMRI studies. The functional properties of core, medial belt, and lateral belt field groups were then analyzed. Field groups were distinguished by tonotopic organization, frequency selectivity, intensity sensitivity, contralaterality, binaural enhancement, attentional modulation, and hemispheric asymmetry. In general, core fields showed greater sensitivity to sound properties than did belt fields, while belt fields showed greater attentional modulation than core fields. Significant distinctions in intensity sensitivity and contralaterality were seen between adjacent core fields A1 and R, while multiple differences in tuning properties were evident at boundaries between adjacent core and belt fields. The reliable differences in functional properties between fields and field groups suggest that the basic primate pattern of auditory cortex organization is preserved in humans. A comparison of the sizes of functionally defined ACFs in humans and macaques reveals a significant relative expansion in human lateral belt fields implicated in the processing of speech
Survey of Photochemical and Rate Data for Twentyâeight Reactions of Interest in Atmospheric Chemistry
Photochemical and rate data have been evaluated for 28 gas phase reactions of interest for the chemistry of the stratosphere. The results are presented on data sheets, one per reaction. For each reaction, the available data are summarized. Where possible there is given a preferred value for the rate constant or, for the photochemical reactions, preferred values for primary quantum yields and optical absorption coefficients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87745/2/267_1.pd
Synthesis of CdS and CdSe nanocrystallites using a novel single-molecule precursors approach
The synthesis of CdS and CdSe nanocrystallites using the thermolysis of several dithioor
diselenocarbamato complexes of cadmium in trioctylphosphine oxide (TOPO) is reported.
The nanodispersed materials obtained show quantum size effects in their optical spectra
and exhibit near band-edge luminescence. The influence of experimental parameters on
the properties of the nanocrystallites is discussed. HRTEM images of these materials show
well-defined, crystalline nanosized particles. Standard size fractionation procedures can
be performed in order to narrow the size dispersion of the samples. The TOPO-capped CdS
and CdSe nanocrystallites and simple organic bridging ligands, such as 2,2Âą-bipyrimidine,
are used as the starting materials for the preparation of novel nanocomposites. The optical
properties shown by these new nanocomposites are compared with those of the starting
nanodispersed materials
Modelling the production, profit, and greenhouse gas emissions of Irish sheep flocks divergent in genetic merit
peer-reviewedCONTEXTSheep production industries face the challenge of increasing farm production and profit while reducing environmental impacts. OBJECTIVESGenetic selection using multi-trait breeding indices can be used to improve flock productivity, profitability, and greenhouse gas (GHG) emissions intensities (kg CO2-eq /kg of product), however validation of the improved performance of animals ranked higher on breeding indices at a flock level is required. METHODSPhenotypic data from 387,580 production records of animals born between 2018 and 2020 of known genetic merit in commercial flocks were inputted to an established bio-economic model. Two contrasting flocks were compared, a flock of ewes ranked High (top 20%) on the Irish replacement Index bred with rams ranked High on the replacement and terminal indices, and a flock of ewes ranked Low (bottom 20%) on the Irish replacement Index bred with rams ranked Low on the replacement and terminal indices. The two flocks were then simulated using life cycle assessment to estimate the GHG emissions profile for both systems. RESULTS AND CONCLUSIONFlock weaning rates were 1.70 and 1.53 lambs weaned per ewe presented for breeding for the High and Low genetic merit flocks, respectively. The flock of High genetic merit ewes sold 0.17 more lambs per ewe, equating to 3.29 kg more lamb carcass per ewe, than the flock of Low genetic merit ewes; lambs from the High genetic merit flock were also sold at an earlier age. The greater production of the High genetic merit flocks resulted in an additional âŹ18/ewe net profit than the Low genetic merit flock. Although total flock GHG emissions were higher for the High genetic merit flock, GHG emissions intensities were lower at 21.7 and 23.3 kg CO2-eq /kg lamb carcass sold for the High and Low genetic merit flocks, respectively. The lower emissions intensity of the High genetic merit flock was due to the dilution effect of higher lamb production and lambs being drafted for slaughter ealier. SIGNIFICANCEThe results suggest Irish sheep producers can make substantial profit gains through selection according to the national breeding indices while also reducing their environmental impact, and farmers should consider genetic merit when purchasing their rams, particularly sires of replacement ewe lambs
Estimation of ultrasonic attenuation and mean backscatterer size via digital signal processing
The backscattered rf signals from the lungs of fetal sheep during their last trimester of development were digitized and processed in an attempt to correlate ultrasonic parameters with measured functional parameters related to lung maturation. The broad-band, post-TGC, rf signal of a commercial B-mode ultrasonic scanner was digitized at a sampling rate of 25 MHz. Sorting excluded data from regions of rib shadowing and other nonlung structures from analysis. The sorted data were used to estimate the slope of the ultrasonic attenuation coefficient with respect to frequency via linear regression on the average difference of the logarithm of power spectra from separated data segments. The power spectra were also corrected for attenuation, averaged and used to compute the power cepstrum of the backscattered signal which can be related to mean backscatterer radius. Results are presented for eight fetal sheep.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24941/1/0000368.pd
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