Study of Civil Markets for Heavy-Lift Airships

The civil markets for heavy lift airships (HLAs) were defined by first identifying areas of most likely application. The operational suitability of HLAs for the applications identified were then assessed. The operating economics of HLAs were established and the market size for HLA services estimated by comparing HLA operating and economic characteristics with those of competing modes. The sensitivities of the market size to HLA characteristics were evaluated and the number and sizes of the vehicles required to service the more promising markets were defined. Important characteristics for future HLAs are discussed that were derived from the study of each application, including operational requirements, features enhancing profitability, military compatibility, improved design requirements, approach to entry into service, and institutional implications for design and operation

Evaluation of different fungicides applied as seed tuber treatments for the control of potato silver scurf

La tache argentée de la pomme de terre (Solanum tuberosum), causée par le champignon Helminthosporium solani, est une maladie affectant la qualité du tubercule. L’objectif de cette étude était d’évaluer l’efficacité de différents fongicides, appliqués sur les tubercules de semence, à contrer le développement de la tache argentée. Pour ce faire, des tubercules de semence infectés par H. solani ont été traités avec l’un des fongicides suivants : talc, fludioxonil, mancozeb, iprodione, thiabendazole, imazalil et azoxystrobin. Ils ont, par la suite, été plantés au champ. Les essais ont été réalisés au Québec sur trois sites en 1998 et deux sites en 1999. Les résultats obtenus montrent que, sous nos conditions expérimentales, ces fongicides, appliqués en traitement de semence, n’ont pas affecté significativement les rendements totaux et vendables ainsi que la sévérité de la tache argentée sur les tubercules-fils au moment de la récolte et après différentes périodes d’entreposage. D’autre part, cette étude a permis de mettre en évidence l’influence des sites expérimentaux sur le développement de la tache argentée et suggère que l’inoculum du sol joue un rôle dans l’épidémiologie de cette maladie.Silver scurf of potatoes (Solanum tuberosum), caused by the fungus Helminthosporium solani, is an important surface-blemishing disease of potato tubers. The objective of the study was to evaluate the efficacy of different fungicides applied to potato seed tubers for control of silver scurf. Field trials were conducted in Québec province in 1998 and 1999. Potato seed tubers infected with H. solani were treated with either talc, fludioxonil, mancozeb, iprodione, thiabendazole, imazalil or azoxystrobin, and planted at three locations in 1998 and two locations in 1999. The results showed that, under our experimental conditions, the fungicides tested, applied as seed treatments, did not significantly influence total and marketable yields as well as silver scurf severity on daughter tubers at harvest and after different storage periods. In addition, this study showed the influence of the experimental locations on silver scurf development and suggests that soil inoculum plays a role in the epidemiology of the disease

Caractérisation structurale et fonctionnelle des interactions impliquant TFIIH et les domaines de transactivation viraux

Le facteur de transcription IIH (TFIIH) joue un rôle crucial dans la transcription et dans la réparation de l’ADN. La sous-unité Tfb1/p62 (levure et humain) de TFIIH interagit avec de nombreux facteurs de transcription (p53, NFκB, TFIIEα) et de réparation (Rad2/XPG and Rad4/XPC) (1). La majorité des interactions avec Tfb1/p62 requiert le domaine d’homologie à la Pleckstrin (PH) localisé dans la région N-terminal de la protéine (2, 3). Ce domaine PH forme des complexes avec des domaines de transactivation acide provenant de protéines cibles impliquées dans la transcription et la réparation de l’ADN. De récentes études ont montré que Tfb1/p62 est une cible pour les protéines virales telles que la protéine VP16 du virus de l’herpès simplex (HSV) de type 1, la protéine E1 du virus du papillome humain (VPH) et la protéine EBNA-2 du virus Epstein-Barr (EBV) (4, 5). Ces protéines virales interagissent avec la sous-unité Tfb1/p62 par un domaine de transactivation acide suggérant une interaction similaire à ce qui est observé chez les facteurs de transcription humains comme p53. Ce mémoire présente une caractérisation structurelle et fonctionnelle du complexe formé par la protéine virale EBNA2 et la protéine humaine Tfb1/p62. L’analyse est faite en utilisant le titrage calorimétrique isotherme (ITC), la résonance magnétique nucléaire (RMN) et une expérience de transactivation chez la levure. Cette étude amène une plus grande compréhension des protéines impliquées dans les maladies comme le lymphome de Burkitt et le lymphome de Hodgkin qui sont souvent associées à l’infection à l’EBV (revue dans (6)) et caractérise une cible potentielle pour un antiviral.The general transcription factor IIH (TFIIH) plays crucial roles in both transcription and DNA repair. Tfb1/p62 (yeast and human), one of the ten/eleven subunits of TFIIH, has been shown to interact with several important transcription (p53, NFκB, TFIIEα) and repair factors (Rad2/XPG and Rad4/XPC) (1). Most of the interactions with Tfb1/p62 require the Pleckstrin homology (PH) domain located at the amino-terminal end of the protein (2, 3). This PH domain in particular forms complexes with highly acidic domains from target proteins involved in both transcriptional activation and DNA repair. Recent studies has shown that the Tfb1/p62 subunit of TFIIH is also targeted by a number of viral proteins including the Herpes Simplex virus (HSV) protein VP16, the Human papillomavirus (HPV) protein HPV E1 and the Epstein-Barr virus (EBV) protein EBNA-2 (4, 5). These viral proteins interact with the Tfb1/p62 subunit via acidic domain which suggests that they are forming similar interactions as the one observed with human transcription and repair factors. This thesis provides a structural and functional characterization of the complex formed by the viral proteins EBNA2 and the human protein Tfb1/p62 subunit of TFIIH. The analysis is done using isothermal titration calorimetry (ITC), nuclear magnetic resonance (NMR) spectroscopy and a yeast activation assay. This study brings a greater understanding of proteins implicated in diseases such as the Burkitt’s lymphoma directly linked to an EBV infection (review in (6)) and shows a viable target for antiviral drug

On The Effect of Giant Planets on the Scattering of Parent Bodies of Iron Meteorite from the Terrestrial Planet Region into the Asteroid Belt: A Concept Study

In their model for the origin of the parent bodies of iron meteorites, Bottke et al proposed differentiated planetesimals that were formed in the region of 1-2 AU during the first 1.5 Myr, as the parent bodies, and suggested that these objects and their fragments were scattered into the asteroid belt as a result of interactions with planetary embryos. Although viable, this model does not include the effect of a giant planet that might have existed or been growing in the outer regions. We present the results of a concept study where we have examined the effect of a planetary body in the orbit of Jupiter on the early scattering of planetesimals from terrestrial region into the asteroid belt. We integrated the orbits of a large battery of planetesimals in a disk of planetary embryos, and studied their evolutions for different values of the mass of the planet. Results indicate that when the mass of the planet is smaller than 10 Earth-masses, its effects on the interactions among planetesimals and planetary embryos is negligible. However, when the planet mass is between 10 and 50 Earth-masses, simulations point to a transitional regime with ~50 Earth-mass being the value for which the perturbing effect of the planet can no longer be ignored. Simulations also show that further increase of the mass of the planet strongly reduces the efficiency of the scattering of planetesimals from the terrestrial planet region into the asteroid belt. We present the results of our simulations and discuss their possible implications for the time of giant planet formation.Comment: 20 pages, 7 figures, accepted for publication in Ap

Climate Variability and Local Environmental Stressors Influencing Migration in Nang Rong, Thailand

Scholars point to climate change, often in the form of more frequent and severe drought, as a potential driver of migration in the developing world, particularly in populations that rely on agriculture for their livelihoods. To date, however, there have been few large-scale, longitudinal studies that explore the relationship between climate change and migration. This study significantly extends current scholarship by evaluating distinctive effects of slow onset climate change and short-term extreme events upon different migration outcomes. Our analysis models the effect of the environment--as measured by Normalized Difference Vegetation Index (NDVI) and the occurrence of El Nino Southern Oscillation (ENSO) events—on migration out of Nang Rong. Our preliminary findings indicate that predominantly dry El Niño periods of 24 months duration lead to outmigration, while predominantly wetter La Niña periods of 12-month duration reduce outmigration. Clustered monthly patterns of annual NDVI fluctuation indicate that villagers living in pixels that exhibit early, consistently higher, and steep rising green-up are less likely to migrate out in the subsequent year

Genetic noise in the cyanobacterial circadian oscillator

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, June 2005.Includes bibliographical references (p. 155-161).Clocks are generally considered as quintessential examples of accurate and precise devices. Biological clocks however, are continually subjected to intracellular and extracellular fluctuations that might reduce the fidelity of this periodic timer. One fundamental limitation that might set an upper bound on the fidelity is the stochastic nature of gene expression creating a noisy intracellular environment. Circadian rhythms, driven by oscillators which provide cells with an internal clock that controls the gene expression program, have been observed in a wide range of organisms from cyanobacteria to mammals. To explore the impact of stochastic expression fluctuations on the performance of the circadian clock, it is necessary to monitor single cells, since population experiments will average out these fluctuations. The cyanobacterium Synechococcus elongatus PCC7942 is an excellent candidate for this study since its core circadian oscillator is well explored. We therefore measured, in single cells, the expression fluctuations of a fluorescent reporter driven by the cyanobacterial circadian oscillator. Repeated microscopic imaging of individual cells and their progeny revealed a robust circadian rhythm, and experiments with cells lacking the proposed central clock proteins confirm the crucial role they play in Synechococcus. Experiments conducted by microscopy and flow cytometry establish that the majority of genetic noise in Synechococcus arises from fluctuations uncorrelated between multiple genes (and therefore does not originate with a global clock noise).(Cont.) We observed via flow cytometry measurements a significant variability in cell-to-cell gene expression which is most pronounced during periods of net protein synthesis. An analytic model reveals that this nonequilibrium effect arises when protein lifetimes are comparable to the circadian period and the mean number of proteins translated per mRNA transcript is large. Stochastic Monte Carlo simulations verify this interpretation by providing a window into genetic behavior on an individual cell level. Estimates of the genetic noise supplied by intrinsic (uncorrelated), extrinsic (correlated within individual cells), and "clock" (unexplained sources with a 24 hour period) noise are developed. A quantitative description of noisy oscillators will be necessary for ultimately understanding the fidelity of circadian timekeeping and might inspire the design of robust synthetic oscillators.by Jeffrey R. Chabot.Ph.D

The CountEm software: simple, efficient and unbiased population size estimation

Population size estimation is essential in ecology and conservation studies. Aerial photography can facilitate this laborious task with high resolution images. However, in images with thousands of individuals exhaustive manual counting is tedious, slow and difficult to verify. Computer vision software may work under some particular conditions but they are generally biased and known to fail in several situations. The CountEm software is a simple alternative based on geometric sampling. It provides a fast and unbiased size estimation for all sorts of populations. The only requirement is that the discrete objects (e.g. animals) in the target population are unambiguously distinguishable for counting in a still image. Typical relative standard errors in the 5?10% range are obtained after counting ~200 properly sampled animals in about 5?min irrespective of population size. The CountEm ver. 1.4.1 is presented here, which includes a guided mode with a simple software interface.MC acknowledges financial support from the AYA-2015-66357-R (MINECO/FEDER) project

Fast-neutron induced background in LaBr3:Ce detectors

The response of a scintillation detector with a cylindrical 1.5-inch LaBr3:Ce crystal to incident neutrons has been measured in the energy range En = 2-12 MeV. Neutrons were produced by proton irradiation of a Li target at Ep = 5-14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr3:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced gamma rays emitted by the LaBr3:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr3:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the results of simulations to predict the response of LaBr3:Ce detectors for a range of crystal sizes to neutron irradiation in the energy range En = 0.5-10 MeVComment: 28 pages, 10 figures, 4 Table