Absolute excitation cross sections of He⁺ in 20-100 keV He⁺-He collisions using energy-loss spectrometry

Application of positive-ion energy-loss spectrometry has been extended to include experimental determination of absolute excitation cross sections of ground state helium ions. Helium ion-atom collisions were studied for impact energies ranging between 20-100 keV, in 10 keV intervals. The data were taken with an apparatus resolution between 0.6-o.8 eV FWHM. Cross sections for transitions from ground state to the second and third principal quantum levels of the ion plotted as a function of impact energy were still rapidly increasing at 100 keV. The cross sections at this energy were 1.64(± 0.28) x 10⁻¹⁸cm² for He⁺(l²s1/2) -\u3e He⁺(n = 2) and 3.46(± 0.45) x 10⁻¹⁹cm² for He⁺(l²s1/2) -\u3e He⁺(n = 3) --Abstract, Page ii

CHROMIUM, COPPER, AND ARSENIC CONCENTRATION AND SPECIATION IN SOIL ADJACENT TO CHROMATED COPPER ARSENATE (CCA) TREATED LUMBER ALONG A TOPOHYDROSEQUENCE

Arsenic (As), Chromium (Cr), and Copper (Cu) are ubiquitous in soils as a result of anthropogenic and geogenic processes. The fate of As, Cr, and Cu in the environment is largely governed by their speciation, which is influenced by soil physiochemical properties. This study investigated the influence of soil physiochemical properties and landscape position on As, Cr, and Cu concentration and speciation in soils adjacent to Chromated Copper Arsenate (CCA) treated lumber fence posts. Concentration gradients showed elevated total As and Cu adjacent to the three fence posts, which decreased with increasing distance from the posts. In addition, As and Cu had higher concentrations in the surface soil samples than the subsoil samples possibly due to enhanced weathering of the CCA treated posts at the surface. Concentrations of As, Cr, and Cu were similar among the Maury and Donerail silt loam, however, they were closer to the background concentration in the Newark silt loam, a partially hydric soil, indicating mobility of the metals. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy indicates As(V) is the predominate species which is principally coordinated with Fe and Al whereas, Cu(II) is coordinated with soil organic matter. Overall, the use of CCA treated lumber as a metal source can help determine how soil properties influence mobility and speciation of As, Cr, and Cu across the soil landscape

The systemic activity of mutualistic endophytic fungi in Solanaceae and Cucurbitaceae plants on the behaviour of the phloem-feeding insects <em>Trialeurodes vaporariorum, Aphis gossypii </em>and<em> Myzus persicae</em>

The biocontrol activity of mutualistic endophytic fungi inoculated into the rhizosphere on the root-knot nematode Meloidogyne incognita and the phloem-feeding insects: Trialeurodes vaporariorum (Westwood) the green house whitefly (GHWF), Aphis gossypii (Glover) the melon aphid, and Myzus persicae (Sulzer) the green peach aphid were investigated on host plants in two plant families. Fusarium oxysporum strain 162 (Fo162) was successfully re-isolated from the roots of squash, melon and pepper, 27.8, 27.4 and 28.8 percent respectively, following endophyte pre-inoculation at sowing. The results showed for the first time that Fo162 was able to effectively colonize these three new host plants. Early root penetration of M. incognita was reduced 83, 70 and 73 percent in the three plants, respectively. In the absence of Fo162, the level of nematode galling was significantly higher in all crops compared to the rate of galling on endophyte inoculated plants. Organic matter amendments did not affect the biological control activity of Fo162. Strain Fo162 as well as five other endophytic isolates with known biological control activity toward plant-parasitic nematodes, were investigated for their potential to induce systemic effects against the GHWF on tomato. The endophytic isolates of Trichoderma atroviride MT-20 and S-2 as well as Fo162 added to the soil at sowing significantly reduced the number of GHWF on the leaves of tomato over the controls in a choice-test as measured over a 10 day period after insect release. The highest level of biocontrol activity was obtained with Fo162. The endophytic fungi did not alter chlorophyll content of the tomato leaves, which was thought to have influenced host selection behaviour. The choice-test also demonstrated that Fo162 negatively affected GHWF behaviour on tomato, squash, and melon at the time of host selection and oviposition. 79 and 74 percent of the adults and eggs detected on the tomato leaves were found on untreated plants, whereas on squash and melon plants the presence of Fo162 reduced host preference of the GHWF equally 80 percent. Significant negative effects of Fo162 on T. vaporariorum reproduction in tomato, A. gossypii in melon and squash as well as on M. persicae in pepper were also detected. Tomato plants treated with Fo162 had a reduced number of 2nd and 3rd nymphal stages and total eggs that were able to complete their life cycle. In squash there was a significant negative effect on the reproductive rate of the melon aphid and in Fo162 treated plants as compared to the control plants. Pepper plants inoculated with Fo162 also had a negative effect on the reproduction of the green peach aphid. Final populations only reached 15% on treated plants of that attained on the untreated plants. RP-HPLC analysis demonstrated that tomato, squash, melon and pepper plants colonized by Fo162 had altered concentrations of metabolite accumulation both in the presence and in the absence of the phloem-feeding insects. Metabolite accumulation in the presence of the phloem-feeding insect populations increased and was negatively correlated with different developmental stages of T. vaporariorum. The results of the present studies demonstrated that the mutualistic fungal endophytes are able to induce systematic resistance in host plants when applied to the soil at sowing. Endophytic root colonization enhanced systemically plant defence mechanisms simultaneously against the root-knot nematode M. incognita in the roots and toward phloem-feeding insects in the leaves.Systemische Aktivität von mutualistisch endophytischen Pilzen in Solanaceaen und Cucurbitaceaen Pflanzen auf das Verhalten der Phloem-ernährenden Insekten Trialeurodes vaporariorum, Aphis gossypii und Myzus persicae Die biologische Kontrollaktivität von mutualistischen endophytischen Pilzen, inokuliert in die Rhizosphäre, gegen den Wurzelgallennematoden Meloidogyne incognita und die Phloem-ernährenden Insekten, Weiße Fliege (GHWG) Trialeurodes vaporariorum (Westwood), die Blattlaus Aphis gossypii (Glover) und die grüne Pfirsich Blattlaus Myzus persicae (Sulzer) wurde an Pflanzen aus zwei Familien untersucht.Fusarium oxysporum Stamm 162 (Fo162) wurde erfolgreich von Gurke, Melone und Paprika re-isoliert, mit Kolonisationsraten von jeweils 27,8%, 27,41% und 28,84%. Diese Ergebnisse zeigten zum ersten mal, dass Fo162 effektiv die Wurzeln von diesen Kulturpflanzen kolonisieren konnte. Die frühe Wurzeleindringung von M. incognita wurde im Vergleich zur Kontrollvariante jeweils in jeder Kulturpflanze um 83%, 70% und 73% reduziert. In Abwesenheit von Fo162 war die Gallenbildung durch die Nematoden signifikant höher als in inokulierten Pflanzen. Die Stärke der biologischen Kontrolle wurde nicht durch organische Bestandteile im Boden beeinflusst. Stamm Fo162 und fünf weitere endophytische Isolate mit bekannter biologischer Kontrollaktivität gegen pflanzenparasitäre Nematoden wurden auf die die Bildung einer systemischen Resistenz gegen GHWG an Tomaten getestet. Die endophytischen Isolate von Trichoderma atroviride MT-20 und S-2 als auch Fo162 inokuliert während der Saat, reduzierten die Anzahl von GHWG an den Pflanzen zehn Tage nach Freilassung signifikant. Das höchste Level der Kontrollaktivität wurde mit Fo162 erziehlt. Ein Einfluss der Endophythen auf den Chlorophyll Gehalt von Blättern der Tomate konnte nicht nachgewiesen werden. Fo162 hatte einen negativen Einfluss auf Auswahl und Eiablage der weißen Fliege an Tomate, Gurke und Melone. 79 und 74 Prozent der Adulten und Eier an Tomatenpflanzen wurden auf unbehandelten Pflanzen gefunden, wobei an Gurke und Melone die Präsenz von Fo162 die Wirtspräferenz um 80% senkte. Signifikante negative Effekte von Fo162 auf die Vermehrung der GHWG an Tomate, A. gossypii an Melone und Gurke, als auch von M. persicae an Paprika wurden nachgewiesen. An Tomatenpflanzen behandelt mit Fo162, wurde die Anzahl des zweiten und dritten Larvenstadiums und die Anzahl der Eier, welche den Lebenszyklus beendeten, reduziert. Die Kolonistation der Melonenblattlaus auf Fo162 inokulierten Gurkenpflanzen zeigte einen negativen Effekt im Vergleich zu den Kontrollpflanzen. An Paprika reduzierte Fo162 die Vermehrungsrate der grünen Pfirsischblattlaus um 85% im Vergleich zu den unbehandelten Pflanzen. RP-HPLC Analysen der mit Fo162 behandelten Tomaten, Gurken und Paprika Pflanzen ergaben eine Veränderung der Metabolitenproduktion in den Blättern sowohl wenn die Insekten präsent waren als auch ohne Präsenz der Insekten. Wenn die verschiedenen Insektenpopulationen vorhanden waren, war die Metabolitbildung ebenfalls erhöht und negativ korreliert mit T. vaporariorum Entwicklungsstadien. Die Ergebnisse der vorliegenden Studie demonstrierten, dass die mutualistischen Endophyten in der Lage waren eine induzierte Resitenz hervorzurufen wenn sie während der Saat inokuliert wurden. Wurzelbesiedlung durch Endophyten erhöhte die systemischen Pflanzen-Abwehrmechanismen, gleichzeitig gegen die Wurzelgallennematode M. incognita in den Wurzeln, als auch gegen Phloem saugende Insekten an den Blättern

Star occultation measurements as an aid to navigation in cis-lunar space

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1962.Includes bibliographical references (leaf 85).by Roy Vincent Keenan, John Donald Regenhardt.M.S

Measuring and modeling the (limited) consistency of free choice attitude questions

On average, respondents who give a positive answer to a binary free choice attitude question are NOT more likely, if surveyed again, to respond positively than to response negatively. However, stronger brands obtain more repeated positive answers. Our model shows why these two effects have to happen, even though all brands in a category benefit from the same reliability.survey reliability; attitude measurement; stochastic models; beta-binomial model; brand image; market research

Replication confers β cell immaturity.

Pancreatic β cells are highly specialized to regulate systemic glucose levels by secreting insulin. In adults, increase in β-cell mass is limited due to brakes on cell replication. In contrast, proliferation is robust in neonatal β cells that are functionally immature as defined by a lower set point for glucose-stimulated insulin secretion. Here we show that β-cell proliferation and immaturity are linked by tuning expression of physiologically relevant, non-oncogenic levels of c-Myc. Adult β cells induced to replicate adopt gene expression and metabolic profiles resembling those of immature neonatal β that proliferate readily. We directly demonstrate that priming insulin-producing cells to enter the cell cycle promotes a functionally immature phenotype. We suggest that there exists a balance between mature functionality and the ability to expand, as the phenotypic state of the β cell reverts to a less functional one in response to proliferative cues

Experiences of JCU MBBS graduates in remote northern Australian towns: preliminary findings

Over 65% of all James Cook University (JCU) medical graduates practise outside of major cities (compared to 20% of all Australian clinicians), including 5% who choose to practice in remote northern Australian towns such as Mount Isa, Darwin, and Palm and Thursday Islands. Many remote towns have high proportional Aboriginal and Torres Strait Islander populations. Little is known about the challenges and pressures for Australian doctors practising in remote locations; including community expectations around advocacy and leadership roles for graduates from Aboriginal or Torres Strait Islander cultures