Application of advanced computational codes in the design of an experiment for a supersonic throughflow fan rotor

Increased emphasis on sustained supersonic or hypersonic cruise has revived interest in the supersonic throughflow fan as a possible component in advanced propulsion systems. Use of a fan that can operate with a supersonic inlet axial Mach number is attractive from the standpoint of reducing the inlet losses incurred in diffusing the flow from a supersonic flight Mach number to a subsonic one at the fan face. The design of the experiment using advanced computational codes to calculate the components required is described. The rotor was designed using existing turbomachinery design and analysis codes modified to handle fully supersonic axial flow through the rotor. A two-dimensional axisymmetric throughflow design code plus a blade element code were used to generate fan rotor velocity diagrams and blade shapes. A quasi-three-dimensional, thin shear layer Navier-Stokes code was used to assess the performance of the fan rotor blade shapes. The final design was stacked and checked for three-dimensional effects using a three-dimensional Euler code interactively coupled with a two-dimensional boundary layer code. The nozzle design in the expansion region was analyzed with a three-dimensional parabolized viscous code which corroborated the results from the Euler code. A translating supersonic diffuser was designed using these same codes

Zygotic Expression of the caudal Homolog pal-1 Is Required for Posterior Patterning in Caenorhabditis elegans Embryogenesis

AbstractPrevious work has shown that the Caenorhabditis elegans gene pal-1, a homolog of Drosophila caudal, is required maternally for blastomere specification in the early embryo and postembryonically for tail development in males. We show here that embryonic (zygotic) transcription of pal-1 is also required for posterior patterning during later embryogenesis. Embryos homozygous for strong loss-of-function mutations arrest as nonviable L1 larvae with gross posterior defects. PAL-1 protein produced from zygotic transcripts is expressed dynamically during gastrulation and morphogenesis in specific cells of all major lineages except the germ line. Most expressing cells are undergoing cell movements or forming midline structures or both. Mutant embryos exhibit defects involving most of the expressing cells. Aberrant early cell positions are observed in posterior hypodermis, both in the C-lineage cells that express pal-1 and in the neighboring hypodermal seam cell precursors, which do not, as well as in posterior muscle derived from the C and D lineages. Defects in late gastrulation, ventral hypodermal enclosure, and formation of the rectum result from failures of cell movements of ABp and MS descendants. Limited mosaic analysis supports the view that most of the required pal-1 functions are cell autonomous

The Effects of Different Types of Internal Controls on Self-Control

One reason companies implement internal controls is to reduce the likelihood of unethical behavior. Yet, ego depletion theory suggests that some controls may cause reductions in employees’ self-control, which could undermine the ability of controls to reduce unethical behavior. We examine whether various types of controls impact self-control and ethical judgments. Our results show that contrary to the ego depletion hypothesis, we find no significant relation between self-control and internal controls. Furthermore, we find that controls have no effect on ethical judgments or ethical ideology. Thus, our results suggest that internal controls do not differentially impact self-control and ethical decision-making

Gene expression and pathway analysis of ovarian cancer cells selected for resistance to cisplatin, paclitaxel, or doxorubicin

<p>Abstract</p> <p>Background</p> <p>Resistance to current chemotherapeutic agents is a major cause of therapy failure in ovarian cancer patients, but the exact mechanisms leading to the development of drug resistance remain unclear.</p> <p>Methods</p> <p>To better understand mechanisms of drug resistance, and possibly identify novel targets for therapy, we generated a series of drug resistant ovarian cancer cell lines through repeated exposure to three chemotherapeutic drugs (cisplatin, doxorubicin, or paclitaxel), and identified changes in gene expression patterns using Illumina whole-genome expression microarrays. Validation of selected genes was performed by RT-PCR and immunoblotting. Pathway enrichment analysis using the KEGG, GO, and Reactome databases was performed to identify pathways that may be important in each drug resistance phenotype.</p> <p>Results</p> <p>A total of 845 genes (p < 0.01) were found altered in at least one drug resistance phenotype when compared to the parental, drug sensitive cell line. Focusing on each resistance phenotype individually, we identified 460, 366, and 337 genes significantly altered in cells resistant to cisplatin, doxorubicin, and paclitaxel, respectively. Of the 845 genes found altered, only 62 genes were simultaneously altered in all three resistance phenotypes. Using pathway analysis, we found many pathways enriched for each resistance phenotype, but some dominant pathways emerged. The dominant pathways included signaling from the cell surface and cell movement for cisplatin resistance, proteasome regulation and steroid biosynthesis for doxorubicin resistance, and control of translation and oxidative stress for paclitaxel resistance.</p> <p>Conclusions</p> <p>Ovarian cancer cells develop drug resistance through different pathways depending on the drug used in the generation of chemoresistance. A better understanding of these mechanisms may lead to the development of novel strategies to circumvent the problem of drug resistance.</p

Superstrengthening Bi_2Te_3 through Nanotwinning

Bismuth telluride (Bi_2Te_3) based thermoelectric (TE) materials have been commercialized successfully as solid-state power generators, but their low mechanical strength suggests that these materials may not be reliable for long-term use in TE devices. Here we use density functional theory to show that the ideal shear strength of Bi_2Te_3 can be significantly enhanced up to 215% by imposing nanoscale twins. We reveal that the origin of the low strength in single crystalline Bi_2Te_3 is the weak van der Waals interaction between the Te1 coupling two Te1─Bi─Te2─Bi─Te1 five-layer quint substructures. However, we demonstrate here a surprising result that forming twin boundaries between the Te1 atoms of adjacent quints greatly strengthens the interaction between them, leading to a tripling of the ideal shear strength in nanotwinned Bi_2Te_3 (0.6 GPa) compared to that in the single crystalline material (0.19 GPa). This grain boundary engineering strategy opens a new pathway for designing robust Bi_2Te_3 TE semiconductors for high-performance TE devices