The Role of Sweet Potato Resistance in the Population Dynamics and Development of Meloidogyne Incognita.

Root-knot nematode populations endemic to Louisiana soils were identified to species and race. Meloidogyne incognita (Kofoid and White) Chitwood, (MI) accounted for 97 percent of the populations identified. Of the M. incognita species 55 percent were Race 1, 38 percent Race 3, and 7 percent Race 4. Meloidogyne javanica represented 3 percent of the populations studied. Populations were compared to the M. incognita used in the LSU sweet potato breeding program (MIS) for their virulence on the susceptible \u27Centennial\u27 and resistant \u27Jasper\u27, \u27Jewel\u27, and L4-73. The populations varied in virulence to the sweet potato cultivars with some populations being more virulent than the MIS population. Several populations appeared capable of overcoming resistance exhibited by the sweet potato cultivars. The life cycle of MIS was studied on \u27Centennial\u27, \u27Jasper\u27, \u27Jewel\u27, and W-51. Varietal resistance did not inhibit the initial rate of juvenile penetration, but did reduce the number of juveniles that reached maturity. Resistance reduced the number of juveniles that reached maturity; however, the rate of nematode development was more rapid in the resistant \u27Jewel\u27 than the other cultivars. The effect of MIS on the growth of \u27Centennial\u27 and \u27Jasper\u27 was studied in field plots artifically infested with initial population densities (Pi) ranging from 0-10,000 MIS eggs per 500 cc of soil. Population dynamics were similar on both cultivars; however, higher mid season counts were recorded from \u27Centennial\u27 than from \u27Jasper\u27. The highest Pi levels did not produce the highest mid season counts. Initial Pi levels had similar effects on the growth of \u27Centennial\u27 and \u27Jasper\u27 sweet potatoes. Pi levels were negatively correlated with marketable roots produced and root weight, but positively correlated with total cracked roots, percent cracked roots, and cracking severity ratings. \u27Jasper\u27 was able to tolerate significantly higher Pi levels with better yields and root quality than \u27Centennial\u27. The incidence of cracking of the fleshy root was apparent on both cultivars at low Pi levels

C-CBL phosphorylation status influences colorectal cancer cell survival in a Wnt-dependent manner

Hyperactive Wnt signaling is the seminal event in colorectal cancer (CRC) pathogenesis, where β-catenin serves as a key Wnt mediator enhancing CRC cell proliferation and survival. c-Cbl is a unique E3 ligase, which degrades both mutant and active (tumorigenic) β-catenin. c-Cbl phosphorylation at tyrosine 731 (Y731) regulates its binding and down regulation of β-catenin specifically in the presence of Wnt ligand (Wnt-on state). Since aberrant Wnt signaling activation is found in almost all cases of human CRC, it would be critical to understand the influence of c-Cbl phosphorylation on CRC cell survival. We hypothesized that c-Cbl phosphorylation regulates CRC cell survival in a Wnt dependent manner, a state that is mediated through mutations in β-catenin or adenomatosis polyposis coli (APC). Cbl phosphorylation was examined in a panel of Wnt-off cells with wild-type β-catenin and APC CRC cell line (RKO cell line) and Wnt-on cell lines with mutant APC (Wnt-on- DLD1, HCT15 cell line) or mutant β-catenin (HCT116) using phospho-specific antibodies to c-Cbl tyrosine residues at 700 (Y700), 731 and 774 (Y774) positions. Biological significance of specific phosphorylation sites was evaluated with phospho-inactive mutants of c-Cbl (Y700F, Y731F and Y774F) using both the MTT cell proliferation assay and the non-adherent colony formation assay. Potential meditators of c-Cbl were examined using immunoblotting. Here we show that c-Cbl was phosphorylated at all three major phosphorylation sites (Y700, Y731 and Y774) in both Wnt-off and Wnt-on CRC cell lines. However, the amount of phosphorylation was reduced in Wnt-on CRC cell lines (DLD1, HCT116 and HCT15) compared to Wnt-off (RKO) cell line. Wild-type c-Cbl significantly enhanced survival in RKO cell lines and reduced survivability in DLD1 cell lines. In contrast to the effect of wild-type c-Cbl, Y731F increased CRC cell survival and non-adherent colony forming units. Our preliminary data suggests that c-Cbl Y731 mutation regulates CRC survival through β-catenin. c-Cbl is heavily phosphorylated in CRC cell lines, where wild-type c-Cbl significantly inhibits cell survival in Wnt-on and enhances cell survival in Wnt-off CRC cell lines. Furthermore, our data indicates that Y731 influences CRC survival and colony formation only in Wnt-on cell lines. Though further validation is required, this dichotomy in the effect of c-Cbl phosphorylation on CRC survival being mediated by Wnt status can be further explored as a potentially novel therapeutic target in mutant CRC tumors, which represent more than 90% of CRC cases in humans

Analyses of Two End-User Software Vulnerability Exposure Metrics

The risk due to software vulnerabilities will not be completely resolved in the near future. Instead, putting reliable vulnerability measures into the hands of end-users so that informed decisions can be made regarding the relative security exposure incurred by choosing one software package over another is of importance. To that end, we propose two new security metrics, average active vulnerabilities (AAV) and vulnerability free days (VFD). These metrics capture both the speed with which new vulnerabilities are reported to vendors and the rate at which software vendors fix them. We then examine how the metrics are computed using currently available datasets and demonstrate their estimation in a simulation experiment using four different browsers as a case study. Finally, we discuss how the metrics may be used by the various stakeholders of software and to software usage decisions

A Music Concert with Kimberly Wright and Mark H. Lawrence: A Guest Artist Performance

This is the program for the guest artist performance of Kimberly Wright, on the horn, and Mark H. Lawrence, on the trombone. The guest artists were accompanied by Dr. Russell Hodges on piano. The concert was held on April 8, 1994, in the Recital Hall of the Mabee Fine Arts Center

The Sarbanes-Oxley Act: Legal Implications and Research Opportunities

Congress passed the Sarbanes-Oxley Act to restore investor confidence, which had been deflated by massive business and audit failures, epitomized by the demise of the Enron Corporation and Arthur Andersen LLP. The Act altered the roles and responsibilities of auditors, corporate officers, audit committee members, as well as other participants in the financial reporting process. We evaluate the potential legal implications of some of the Act’s major provisions and anticipate participants’ likely responses. Our evaluation suggests that these provisions will significantly change behavior, increase compliance costs and alter the legal landscape. We also identify promising avenues for future research in light of the new landscape

Hot Dust Clouds with Pure Graphite Composition around Type-I Active Galactic Nuclei

We fitted the optical to mid-infrared (MIR) spectral energy distributions (SEDs) of ~15000 type-I, 0.75<z<2, active galactic nuclei (AGNs) in an attempt to constrain the properties of the physical component responsible for the rest-frame near-infrared (NIR) emission. We combine optical spectra from the Sloan Digital Sky Survey (SDSS) and MIR photometry from the preliminary data release of the Wide Infrared Survey Explorer (WISE). The sample spans a large range of AGN properties: luminosity, black hole mass, and accretion rate. Our model has two components: a UV-optical continuum source and very hot, pure-graphite dust clouds. We present the luminosity of the hot-dust component and its covering factor, for all sources, and compare it with the intrinsic AGN properties. We find that the hot-dust component is essential to explain the (rest) NIR emission in almost all AGNs in our sample, and that it is consistent with clouds containing pure-graphite grains and located between the dust-free broad line region (BLR) and the "standard" torus. The covering factor of this component has a relatively narrow distribution around a peak value of ~0.13, and it correlates with the AGN bolometric luminosity. We suggest that there is no significant correlation with either black hole mass or normalized accretion rate. The fraction of hot-dust-poor AGNs in our sample is ~15-20%, consistent with previous studies. We do not find a dependence of this fraction on redshift or source luminosity.Comment: Accepted for publication in ApJ

Study of the Amplitude of Pressure and Thrust Oscillations in a Lab-Scale Hybrid Rocket

Hybrid rockets are being studied as a potential replacement for the solid rocket boosters on the NASA space shuttle. One physical characteristic of hybrid rockets that must be understood and overcome is potentially severe pressure oscillations during combustion. Pressure oscillations inside the rocket combustion chamber lead to oscillations in the thrust of the rocket. These oscillations are damaging to potential human passengers and cargo and must be minimized. Current theories surmise that the oscillations are caused by combustion chamber geometry, oxygen feed line parameters, and/or fuel combustion characteristics. This study focuses on the role of the fuel characteristics in pressure and thrust oscillations. The standard hybrid rocket fuel is hydroxyl-terminated polybutadiene (HTPB). A fuel additive, guanidinium azo-tetrazolate (GAT), has been shown to increase thrust and impulse of the rocket when added as 15% by mass to the fuel. This study compares the amplitude of the pressure and thrust oscillations of the rocket when burning HTPB fuels and when burning GAT-added fuels. Data from several firings at oxygen flow rates from 0.018 kg/sec to 0.054 kg/sec are analyzed. Results show the GAT-added fuel combustion shows no significant increase or decrease in the amplitude of the pressure and thrust oscillations