Horseweed (Erigeron canadensis) is a competitive winter or summer annual broadleaf weed. When uncontrolled, horseweed can reduce soybean (Glycine max) yields by 93%. Research was conducted to advance our knowledge on horseweed growth stage response to foliar-active and residual herbicides, fall applications, and the utility of differing herbicide technologies. Greenhouse results determined that herbicide efficacy was greatest when applied to early rosette horseweed providing an average control of 70% across herbicide treatments. Field trials determined that preventing new emergence with flumioxazin, added with dicamba or paraquat to kill existing plants in the fall, increased control to 99% the following spring. Field trials also determined that dicamba, applied PRE or POST, provided excellent horseweed control and was an effective soybean technology system for horseweed-infested fields. Saflufenacil controlled existing plants, but residual benefits were unclear. Further research must be done to investigate residual activity of PRE herbicides applied before horseweed emergence.

Les dépôts élaborés par projection thermique sont largement utilisés pour des applications de hautes performantes grâce à leurs propriétés mécaniques élevées (dureté et module d’Young). La détermination de ces propriétés est donc importante. Elles sont habituellement mesurées par des méthodes d’indentation en utilisant des indenteurs Vickers, Knoop et Berkovich. Mais ces méthodes de mesure nécessitent des équipements sophistiqués, une préparation rigoureuse des surfaces et la réalisation qui les rend coûteuse et difficile à mettre en oeuvre. Les travaux de cette thèse portent sur l’étude de la résistance à la perforation comme méthode alternative pour déterminer les propriétés mécaniques de dépôts céramiques élaborés par projection plasma. Pour ce faire, six poudres de compositions chimiques les plus souvent utilisées au niveau de l’industrie ont été sélectionnées pour élaborer les dépôts par projection plasma : Al2O3, TiO2, Al2O3-15wt % TiO2, Al2O3-43wt % TiO2, YSZ et Al2O3-YSZ. Les propriétés physico-chimiques et mécaniques des dépôts ont été déterminées. Les macro et micro duretés ont été déterminées par des indentations Vickers, le module d’Young a été calculé à partir des mesures de la micro dureté Knoop et la ténacité à la fracture a été déterminée à partir des résultats de micro dureté Vickers. La résistance à la perforation en mode statique a été conduite en utilisant des forets pour le perçage de verre et en traçant des courbes de charges (P) en fonction de la profondeur (h) d’enfoncement de la pointe du foret dans la surface du dépôt. Des rapports entre la charge et les aires de contact et de la section transversale de la pointe du foret (P/Ac et P/At respectivement), correspondant à la profondeur de pénétration du foret, ont été établis, permettant de définir la dureté par perforation statique (HDs). A partir des pentes ΔP/ΔAc et ΔP/ΔAt lors de la décharge des courbes P-h, le module d’élasticité par perforation statique (Es) a été déterminé. HDs et Es ont montré une bonne correspondance avec la micro dureté et le module d’Young déterminés par les méthodes classiques d’indentation et une haute reproductibilité des résultats. L’apparition de fissures et d’écaillage sur la surface des dépôts lors de l’étape de charge a mis en évidence une réduction de la pente des courbes P-h qui pourrait être utilisée pour trouver des corrélations avec la ténacité à la fracture. Sous le mode dynamique, les essais de résistance à la perforation ont été conduits en utilisant des forets pour le perçage des métaux (de type HSS) et pour la maçonnerie. Les rapports entre la charge appliquée et les aires de contact et de la section transversale (P/Ac et P/At respectivement) pour une profondeur h de la pointe du foret dans la surface des dépôts ont été utilisés pour calculer la dureté par perforation dynamique (HDD). Les résultats ont montré une bonne correspondance avec la micro dureté Vickers malgré la plus faible reproductibilité que ceux obtenus en mode statique. / Thermal sprayed ceramic coatings are highly used in application where high performance regarding to mechanical properties are required. Thus it is essential to determine the coatings’ mechanical properties (hardness, Young modulus and fracture toughness), which is made by classical indentation methods using Vickers, Knoop and Berkovich indenters. Those methods use sophisticated devices, rigorous sample preparation and demanding time processes in execution and data analysis that make them expensive and complicated in implementation. This research is focused tostudy the drilling resistance as an alternative method to measure the mechanical properties of atmospheric plasma spray ceramic coatings. For these purpose powders of six chemical compositions most widely used in industrial applications were employed as feedstock powders to manufacture coatings by atmospheric plasma spraying: Al2O3, TiO2, Al2O3-15wt % TiO2, Al2O3-43wt % TiO2, YSZ and Al2O3-YSZ. Physical, chemical and mechanical properties have been determined. Macro and micro hardnesses were determined by Vickers indentations, the Young’s modules werecalculated from Knoop micro hardness measurements and fracture toughness from Vickers micro hardness. Static drilling resistance tests were carried out with commercial drill bits used to perforate glass plotting the applied force (P). against the drill bit depth (h). Relationships between the applied force and the bit’s contact or cross sectional areas (P/Ac and P/At respectively) corresponding to the drilled depth (h) were used to set the Static Drilling Hardness (HDs).Furthermore, the slopes in the unloading stage corresponding to ΔP/ΔAc or ΔP/ΔAt were used to calculate the Static Drilling Elastic Modulus (Es). The HDs and Es results exhibit both well fit with the micro-hardness and Young modulus measurements made by classical methods and high reproducibility in the results. It was observed that cracks and spalling produced on the coatings surfaces during loading reduce the slope of the P vs h plot which could be used in future studies to correlate to the toughness of coatings. Dynamic drilling tests using bits to perforate metals (HSS) andmasonry were also carried out. The ratios between applied load and contact or cross sectional areas (P/Ac and P/At respectively) corresponding to the depth (h) of the hole drilled on each coating were used to calculate the Dynamic Drilling Hardness HDD which shows a good fit with the measured hardness on the surface of coatings realized by micro-indentation Vickers but lower reproducibility than those obtained with static drilling hardness results.

No description available.

Corynebacterium striatum (CS) is an underappreciated human pathogen that has been associated with serious infections in both immunocompetent and immunocompromised hosts. CS infections tend to be more frequent in males and major infection sites have included blood stream, lung, and central nervous system. Most are nosocomially acquired and there is a significant association with medical devices ranging from intravascular catheters to central nervous system drainage devices. Empiric therapy with vancomycin is advisable as susceptibility to other agents is variable. Treatment may also include removal of foreign material such as an intravascular catheter. The present review describes the wide spectrum of infections associated with CS and we add a unique case of CS pancreatic abscess where treatment included linezolid.

The fundamental unit of behavior, defined by the discriminated operant, can be reduced to the three-term contingency, which includes an antecedent stimulus, a response, and a reinforcing consequence. Behavioral momentum theory suggests that resistance to disruption (i.e., resistance to change) of operant behavior is governed by the relation between the antecedent stimulus context and the rate of reinforcement within that context (i.e., Pavlovian stimulus-reinforcer relation). Further, behavior momentum theory suggests that resistance to change is independent of the contingency between the response and the reinforcer (i.e., operant response-reinforcer relation). Thus, although additional response-independent food decreases response rates by greatly degrading the response-reinforcer relation, resistance to change is increased because the stimulus-reinforcer relation is enhanced. Inconsistent with behavioral momentum theory, unsignaled delays decrease response rates and resistance to change by slightly degrading the response-reinforcer relation while maintaining equal stimulus-reinforcer relations. Therefore, it is unclear exactly how degrading response-reinforcer relations with response-independent food and delayed reinforcers affects resistance to change because the stimulus-reinforcer relations have generally differed across components and studies. Thus, the present experiment examined whether differentially degrading response-reinforcer relations affects resistance to change while maintaining equal stimulus-reinforcer relations. In the present experiment, a three-component multiple schedule with equal rates of immediate response-dependent reinforcement (15 per hr) was used with pigeons keypecking for food. Equal rates of response-independent food (60 per hr) and 3-s unsignaled delayed reinforcers (60 per hr) were added to two different components in baseline. Thus, the stimulus-reinforcer relations were equal in the two components with added reinforcers and were greater than in the component without added reinforcers . Any differences in resistance to change across the components with added reinforcers should reflect only differences in the response-reinforcer relations because the stimulus-reinforcer relations were equal. Consistent with behavioral-momentum theory, however, resistance to presession feeding, response-independent food presented during intercomponent intervals , and extinction was greater in the components with added reinforcers. There were no differences in resistance to change between the two components with added reinforcers. These results replicate the finding that adding response-independent food increases resistance to change and extends this finding to the effects of added delayed reinforcement.

The prevalence of insecticide resistance in vector species around the world is a continuous threat for any success at mitigating the spread of vector-borne diseases. With a limited arsenal of new insecticides, it is crucial for public health programs to understand the geographic range and the genetic mechanisms of resistance to best approach controlling insect vectors. Insecticide resistance is being increasingly observed in phlebotomine sand fly (Diptera: Psychodidae) populations in both the Old World and New World. Sand flies transmit the protozoans that cause leishmaniasis, a disfiguring disease that kills tens of thousands of people each year. The goal of this dissertation was to have both an applied and basic research focus towards understanding resistance in phlebotomines. I began by comparing in vivo and in vitro methods for blood-feeding two species of sand flies, Phlebotomus papatasi and Lutzomyia longipalpis, in the laboratory, both of which are important leishmaniasis vectors. I investigated the susceptibility of both species to ten different insecticides by calculating lethal concentrations that caused varying levels of mortality. Based on these results, I determined diagnostic doses and diagnostic times for both species to the same ten insecticides using an accepted, but novel, assay for sand flies. Finally, I tested for known mechanisms of insecticide resistance in four artificially resistant-selected colonies of sand flies, as well as tested for novel resistance mechanisms. Through applied research, I developed methods for efficient sand fly rearing and for determination of population resistance to insecticides, tools that have worldwide applicability. Through basic research, I determined that laboratory populations of sand flies have sufficient standing genetic variation needed to survive sublethal doses of insecticides; however, I was unable to develop artificially-selected colonies resistant to these insecticides. My research has generated information to provide new insights into the evolution of insecticide resistance in natural sand fly populations. My results support that resistance development may be possible, but evolutionary challenging, an encouraging finding that may be exploited by vector biologists and public health officials to prevent or slow the development of resistance in sand flies to insecticides

In engineering practice it is important to know which factors affect the thermal and electrical resistance of metal contacts. This thesis is to investigate some of these factors such as surface roughness and contact pressure. Thermal electrical contact resistance ratios for metal contacts were calculated from the experimental data. The technical literature was searched, and several papers were found in which either thermal or electrical contact resistance was studied separately. However, none of the papers recorded data for both thermal and electrical resistances for the same samples. The information found in these papers has been used as a background for understanding the nature of thermal and electrical contact resistance. Both of these contact resistances are primarily a function of the load on the contact and the condition of the surfaces. At low pressures only a small fraction of the total gross area of the contacts is in metal-to-metal contact. Increasing the load, flattens the “hills” and reduces both the thermal and electrical contact resistance. This phenomenon is called “spreading resistance” since the flow of heat or electrical current must spread out after they pass through the restricted areas that are actually in contact. Another type of thermal and electrical resistance, which is called “interface resistance", is caused by a film of foreign material such as an oxide, etc. on the surfaces of the contacting “hills”. If the space between the “hills” of a contact is filled with air, there is a heat flow by convection currents. The literature indicates this quantity of heat flow is approximately one thousandth of the total heat flow through metal contacts. Since the only electrical current conduction mechanism acting between areas not in actual metallic contact is that due to thermionic emission, the electrical resistance for these areas will be extremely high at room temperature for which thermionic emission is negligible. The experimental apparatus to measure both the thermal and electrical contact resistances consists mainly of a bellows-actuated press which is operated remotely under a vacuum bell. The press pressure loads the sample metal wafers. A thin film heat meter is used to indicate the quantity of heat flowing through the metal contacts. The temperature drop caused by the contacts is measured with thermocouples. The temperature difference and the quantity of heat flowing is used to calculate the thermal contact resistance. A strain gage on the bellows-press stem measures the loading on the contact surfaces. Electrical probes are used to measure the electrica1 resistance across the contact surfaces. The thermocouples and electrical resistance probes are permanently installed in the outer two smooth copper wafers. This makes it possible to quickly change to other sets of sample wafers of other metals and finishes. In order to use this permanent arrangement, it is necessary to finish two mating surfaces of the particular set of metal wafers to be tested, similar to the permanent smooth copper wafers so that these two extra mating contact resistances can be found and thus be subtracted from the overall contact resistance. The data indicates that the thermal-electrical contact resistance ratio can be changed by changing the load on the contacts. The heat meter had performed very well, and this new method of measuring heat flow will undoubtedly become a standard method of measuring heat flux.

Indiana University-Purdue University Indianapolis (IUPUI) / Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs), including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to LL-37, mediated by the sensitive to antimicrobial peptide (Sap) transporter, is required for H. ducreyi virulence in humans. Cationic APs are attracted to the negatively charged bacterial cell surface. In other gram-negative bacteria, modification of lipopolysaccharide or lipooligosaccharide (LOS) by the addition of positively charged moieties, such as phosphoethanolamine (PEA), confers AP resistance by means of electrostatic repulsion. H. ducreyi LOS has PEA modifications at two sites, and we identified three genes (lptA, ptdA, and ptdB) in H. ducreyi with homology to a family of bacterial PEA transferases. We generated non-polar, unmarked mutants with deletions in one, two, or all three putative PEA transferase genes. Mutants with deletions in two PEA transferase genes were significantly more susceptible to β-defensins, and the triple mutant was significantly more susceptible to both α- and β-defensins, but not LL-37; complementation of all three genes restored parental levels of AP resistance. Deletion of all three PEA transferase genes also resulted in a significant increase in the negativity of the mutant cell surface, suggesting these three genes contribute to the addition of positively charged moieties on the cell surface. Mass spectrometric analysis revealed that LptA was required for PEA modification of lipid A; PtdtA and PtdB did not affect PEA modification of LOS. In human inoculation experiments, the triple mutant was as virulent as its parent strain. While this is the first identified mechanism of resistance to α-defensins in H. ducreyi, our in vivo data suggest that resistance to cathelicidin may be more important than defensin resistance to H. ducreyi pathogenesis.

Soybean is one of the most important grain legumes grown in US and worldwide, and is a major component of human and animal protein diets. Despite improvements in management practices, and the introduction of improved soybean cultivars, soil borne pathogens continue to cause tremendous yield loss in soybean production each year. Among soil borne pathogens; Soybean Cyst Nematode (SCN) or Heterodera glycines together with Sudden Death Syndrome (SDS) induced by Fusarium virguliforme are responsible for the most damages in soybean fields. The most effective way to control these two pathogens is to develop resistant cultivars. Resistance to any population (HgType) of H. glycines, requires a functional allele at rhg1/Rfs2 locus. The rhg1/Rfs2 gene encodes a receptor-like kinase (RLK) protein. By analysing near isogenic lines (NIL) segregating for rhg1/Rfs2, rhg1-like loci were found at other locations most conservedly on LG B1. While the nature of rhg1 allele was thought to be recessive, heterozygous NIL segregating at the rhg1 locus showed that the resistant allele was dominant. Rhg1 was also inferred to be multigeneic due to absence of recombination between the RLK and other 2 genes. Functional and structural analyses were conducted on the leucine rich repeat (LRR) from RLK protein encoded by GmRLK18-1 within the Rhg1/Rfs2 locus. The LRR of GmRLK18-1 showed a high binding affinity to CLE-like peptides found in both nematode secretions and plant developmental control. Crosslinking assays and native gel analysis of GmRLK18-1-LRR validated its model as a crystal homo-dimer. Larger proteins were also shown to bind the LRR domain, in far-Western analyses both methionine synthase and cyclophilin bound strongly to the LRR domain. Homology and ab-initio modeling of the LRR domain of the GmRLK18-1 was predicted as both a monomer and a homodimer containing intrinsically unstructured regions. Amino acid substitutions found among GmRLK18-1 allotypes A87V, Q115K and H274N were predicted to play crucial roles in protein function and stability. The receptor like kinase (RLK) GmRLK18-1 within the Rhg1/Rfs2 locus underlies a pleiotropic resistance to both SCN and SDS. The resistance allele was shown to be dominant in both heterozygous NILs at Rhg1/Rfs2 and transgenics (hetero- or hemi-zygous). The RLK was found to provide a partial resistance to SCN and importantly a nearly complete resistance to both root and leaf symptoms of SDS. In the presence of Rhg4, the RLK-transgenic plants developed nearly full resistance to SCN. Therefore the RLK was proven to underlie a major portion of the Rhg1/Rfs2 locus.

Transgenic corn and cotton expressing crystalline (Cry) insecticidal proteins from Bacillus thuringiensis (Bt) were commercially introduced in 1996. This technology has greatly improved the control of several key lepidopteran insect pests tobacco budworm, Heliothis virescens (Farbricius), pink bollworm, Pectinophora gossypiella (Saunders), southwestern corn borer, Diatraea grandiosella (Dyar), and European corn borer, Ostrinia nubilalis (Hübner). The corn earworm, Helicoverpa zea, has been more difficult to control using Bt crops and supplemental insecticide applications are often needed to prevent economic losses. A major threat to the longevity of transgenic technology is the evolution of resistance, especially when an insect pest infests both Bt corn and cotton in the same growing season. Similar Cry proteins are currently expressed in both corn and cotton commercial production systems. At least one generation per year develops on Bt corn before infesting cotton. Given that H. zea infests both crop hosts at some point every year, the objectives of this study were to evaluate the contribution and influence of Genuity VT3 PRO corn (expressing Cry1A.105 and Cry2Ab) on H. zea density, fitness, and selection on BollGard II cotton (expressing Cry1Ac and Cry2Ab). Non-Bt and VT3 PRO corn fields were sampled for larval density and any observed larvae were collected. Non-Bt field corn supported 61% more larvae compared to VT3 PRO fields. Larvae infesting non-Bt corn developed faster than those infesting VT3 PRO corn. Larvae collected from VT3 PRO corn had significantly higher pupal weight two out of the three years of this study. Pupae from VT3 PRO corn also had longer pupal duration two out of three years compared to pupae of larvae collected from non-Bt corn. Offspring from larvae reared on VT3 PRO corn had a higher LC50 compared to offspring from larvae reared on non-Bt corn. H. zea susceptibility to Bt is highly variable but the results presented here indicate that dual-gene corn hybrids such as VT3 PRO can select for H. zea populations with a higher propensity for causing damage in Bt cotton.