Alien Registration- Rioux, Delina M. (Limestone, Aroostook County)

https://digitalmaine.com/alien_docs/35186/thumbnail.jp

A Future Large-Aperture UVOIR Space Observatory: Reference Designs

No abstract availabl

Estudios ultraestructurales y citoquímicos de huéspedes y patógenos en algunas enfermedades de marchitamiento fúngicas: una retro e introspeción dirigida al mejor entendimiento de DED

This report presents a survey of previous and more recent ultrastructural and cytochemical investigations of disease development in elm, caused by Ophiostoma novo-ulmi, with results of some comparative studies of other wilt diseases caused by f.spp., of Fusarium oxysporum and of Verticillium sp. For cytochemical studies, probes complexed to colloidal gold to detect cellulose, pectin, chitin, and DNA were used. Thus, the formation of tyloses, pit membrane alterations, and the disease effect on parenchyma cells in mature as well as in young tissue were characterized. Vessel lumina in these plants, in diverse situations, contained heterogeneous matter, among which occurred masses of opaque matter and in certain instances pectin fibrils secreted by parenchyma cells and tyloses. Numerous globoid, opaque bodies of regular sizes, which have been mostly overlooked previously, abounded in vessel elements of U. americana and U. glabra, including trees injected with glucose solutions prior to inoculation. Coarser fibrillar material was also noted in vessel lumina, but mostly shortly after inoculation. Other peculiar forms of O. novo-ulmi are also described. The possible role of the components under study is discussed, and a model for DED is proposed in which hindrance to vessel invasion, including downward spread of the pathogen, and reactions of parenchyma cells are complementary and considered to be conducive to defence mechanisms, including compartmentalization of the invaded xylem.En este informe se presenta una revisión de los más recientes estudios sobre la ultraestructura y la citoquímica del desarrollo infectivo causado por Ophiostoma novo-ulmi en el olmo, y su comparación con otras enfermedades vasculares causada por hongos como Fusarium oxysporum y Verticillium sp. En los estudios citoquímicos se usaron inmunolocalizadores de oro coloidal para la detección de celulosa, pectina, quitina y ADN. De esta manera se caracterizó la formación de tilosas, las alteraciones en las punteaduras, y los efectos de la infección en las células parenquimáticas, tanto en tejidos adultos como jóvenes. En estas plantas, el interior de los elementos conductores contiene, en diversas ocasiones, sustancias heterogéneas en las que aparecen masas de sustancias opacas, así como, en ciertas ocasiones, fibrillas de pectina segregadas por células parenquimáticas y por tilosas. Numerosos cuerpos opacos globulares de tamaño medio, que previamente habían pasado en gran medida inadvertidos, eran abundantes en los elementos conductores de U. americana y U. glabra, incluyendo árboles a los que se inyectó soluciones de glucosa antes de la inoculación. También se detectó la presencia, en el interior de los vasos, de material fibrilar de mayor diámetro, sobre todo al poco de la inoculación. También se describen otras formas peculiares de O. novo-ulmi. Se discute el posible papel de los componentes en estudio, y se propone un modelo para la grafiosis en el cual los obstáculos para la invasión del vaso, incluidas la transmisión corriente abajo del patógeno y la reacción de células parenquimáticas, son complementarios, considerándose que son conducentes a la aparición de mecanismos de defensa, incluida la compartimentación del xilema invadido

The MBLWHOI Library Digital Herbarium

pp. 11-1

Extracellular sheath formation by Sphaeropsis hypodermia and association with its infection in elm trees

Nous avons observé le mode de développement de Sphaeropsis hypodermia (isolé d'une branche d'orme (Ulmus americana) atteinte d'un chancre) dans les milieux suivants : un milieu gélosé (PDA), un tissu essuie-tout (Kimwipes), des blocs de bois d'orme stérilisés à l'autoclave, et des ormes d'Amérique inoculés en serre. Des échantillons de chaque substrat ont été fixés pour les observations en microscopie photonique et en microscopie électronique avec du glutaraldéhyde et du tétroxyde d'osmium. Observés en microscopie électronique, les hyphes accolés au substrat étaient entourés d'une épaisse couche extracellulaire devenant circonscrite par des bandes rigides et contenant des corps opaques simples ou agrégés, ou des masses de matière opaque plus volumineuses dans le cas des blocs de bois d'orme. Sur celui-ci et sur le tissu Kimwipes, la couche extracellulaire s'étendait sur une distance appréciable, loin des cellules fongiques, et avait également pénétré les parois de cellules de parenchyme et des fibres, selon le cas. Dans les ormes inoculés, le champignon a rapidement produit des dommages notables dans les tissus du cambium et colonisé abondamment les régions de l'écorce et du xylème avoisinantes. La pénétration et la dégradation des parois cellulaires de l'écorce étaient marquées, en relation également avec de la matière opaque entourant les cellules du champignon. Cette matière ressemblait à celle liée aux cellules fongiques sur les milieux stérilisés. Bien que les cellules du xylème étaient généralement colonisées, des altérations pariétales n'étaient apparentes que dans les cellules récemment formées. En outre, le passage du champignon d'une cellule à l'autre à travers les parois n'a été observé que dans le cas des éléments de vaisseaux et des cellules de rayon. Concernant les fibres, seule y était visible une bande de matière filamenteuse dans les parois et liant les cellules fongiques présentes dans la lumière de ces fibres. En réponse à la dégradation de parois cellulaires liée à de la matière opaque, l'hypertrophie et l'hyperplasie des cellules du cambium et de l'écorce interne ont été observées, liées possiblement à la formation d'une barrière de protection. On discute du rôle possible de la couche extracellulaire des cellules fongiques in vivo et in vitro.Sphaeropsis hypodermia, isolated from a cankered American elm branch, was grown on agar medium (PDA), on autoclaved wiping paper (Kimwipes), and American elm (Ulmus americana) wood chips, or inoculated into greenhouse-grown American elm saplings. Samples from each treatment were double-fixed with glutaraldehyde and osmium tetroxide and examined with the light and the transmission electron microscopes. Ultrastructurally, the hyphae on PDA and inert substrates appeared surrounded by large extracellular sheaths which were delimited by rigid opaque bands of various thicknesses. The sheaths extended appreciable distances from the fungal cells, as evidenced by their adherence to rigid substrates. Individual or aggregated opaque bodies, even as large masses on elm wood chips, were the main components of the sheath. This opaque material was often associated with penetration and ruptures of the wood cells. Inoculated into elm trees, the fungus rapidly caused pronounced alterations of cambial tissues and colonized the adjoining bark and xylem cells. The prominent penetration and breakdown of the inner and outer bark cells by the fungus were associated with opaque material, particularly in cortical fibres. The material was structurally similar to the sheath formed on the rigid sterilized substrates. In the xylem, only the walls of the recently deposited cells were visibly altered, and although mature fibres were generally colonized, the passage of the fungus from one fibre to another was rarely observed, contrary to the passage from vessel and ray cells to adjoining cells. In that instance, only bands of opaque material present in the walls of fibres were connected with fungal cells in their lumen. In the inner bark and cambial regions, cell hypertrophy and hyperplasia occurred next to host walls that were altered and contained similar opaque material. The extracellular sheath of S. hypodermia under in vitro conditions and the opaque material associated with host wall alterations in vivo are considered to be analogous

Examining Factors that Support Continued Use of Assistive Technology by Postsecondary Students with Disabilities

Students with disabilities are attending postsecondary institutions in growing numbers. As such, disability service providers on campuses are providing more accommodations, including assistive technology (AT). AT can help students with a variety of learning needs; however, many students discontinue use despite the benefits that this technology can provide. To increase our understanding of discontinued use of AT, we collected both quantitative questionnaire data and open-ended written qualitative data. First, we examined three factors theorized to relate to continued use of AT and found that individual factors were more important than the environment or characteristics of the technology itself. Second, we investigated students’ experiences with AT training and determined that the quality of the training experience and not simply attending training, was related to continued use of AT. Furthermore, we provide recommendations for individuals providing training to students. Collectively, the results provide the basis for suggestions concerning support and services offered to students utilizing AT

Ultraestructura de la red alveolar y su relación con el recubrimiento de las paredes vasculares en olmos infectados con Ophiostoma novo-ulmi y en otras plantas infectadas con enfermedades similares de marchitamiento

In elms infected with Dutch elm disease, alveolar networks, demarcated by filamentous-like bands and confluent with similar matter (the coating) accumulating on vessel walls, occurred regularly in vessel elements. Similar material lined vessel walls in inoculated, sterilized, thin elm wood sections fixed by high pressure freezing. The coating was observed to connect with fungal cells and occasionally contained small opaque particles, the size of ribosomes, membranous and vesicular structures, and, following incubation of wood chips taken from diseased samples incubated on an agar medium, it still displayed similar matter. Coating and alveolar bands increased in thickness by confluence of other bands or membranous structures. Similar matter and structures also occurred in other plants affected by similar fungal wilt diseases. In all systems, the compact coating did not label for chitin, cellulose and pectin. In staghorn sumac, the probe for DNA attached to the coating. Altogether, in the light of these data, it appears that the coating and alveolar networks are not inert components, a fact which indicates their primordial probable pathogen origin. It is proposed that these elements might be important not only in the initial infection stages but also in older or recurrent infections at a time when host resistance mechanisms are ineffective.En olmos afectados por la grafiosis, la red alveolar, demarcada por bandas filamentosas, y confluente con acumulaciones de la misma sustancia (cubrición) presentes en las paredes de los vasos, aparece regularmente en los elementos conductores. Sustancias similares tapizan las paredes de los vasos en secciones de madera delgada de olmo inoculada y esterilizada, y posteriormente criofijadas a altas presiones. Se observó que la cubrición se conecta con las células del micelio y que ocasionalmente contenía pequeñas partículas opacas del tamaño de los ribosomas, estructuras membranosas y vesiculares, así como que, tras la incubación de astillas leñosas cogidas de muestras enfermas incubadas en agar, aún se presentaba una sustancia similar. La cubrición y las bandas alveolares aumentaron su espesor en la confluencia con otras bandas o estructuras membranosas. Estructuras y sustancias similares aparecieron también en otras plantas afectadas por enfermedades similares originadas por hongos que producen marchitamiento. En todos los sistemas, la cubrición compacta no pudo ser marcada como quitina, celulosa ni pectina. En zumaque (Rhus typhina), la sonda de ADN se pegó a la cubrición. En resumen, a la vista de estos datos, parece ser que la cubrición y la red alveolar no están formados por componentes inertes, un hecho que indica su probable origen patogénico. Se sugiere que esos elementos podrían ser importantes no sólo en las fases iniciales de la infección, sino también, en infecciones más desarrolladas o recurrentes, en el momento en que los mecanismos de resistencia del hospedante no son efectivos

Survey of Materials for Nanoskiving and Influence of the Cutting Process on the Nanostructures Produced

This paper examines the factors that influence the quality of nanostructures fabricated by sectioning thin films with an ultramicrotome (“nanoskiving”). It surveys different materials (metals, ceramics, semiconductors, and conjugated polymers), deposition techniques (evaporation, sputter deposition, electroless deposition, chemical-vapor deposition, solution-phase synthesis, and spin-coating), and geometries (nanowires or two-dimensional arrays of rings and crescents). It then correlates the extent of fragmentation of the nanostructures with the composition of the thin films, the methods used to deposit them, and the parameters used for sectioning. There are four major conclusions. (i) Films of soft and compliant metals (those that have bulk values of hardness less than or equal to those of palladium, or ≤500 MPa) tend to remain intact upon sectioning, whereas hard and stiff metals (those that have values of hardness greater than or equal to those of platinum, or ≥500 MPa) tend to fragment. (ii) All conjugated polymers tested form intact nanostructures. (iii) The extent of fragmentation is lowest when the direction of cutting is perpendicular to the exposed edge of the embedded film. (iv) The speed of cutting−from 0.1 to 8 mm/s−has no effect on the frequency of defects. Defects generated during sectioning include scoring from defects in the knife, delamination of the film from the matrix, and compression of the matrix. The materials tested were: aluminum, titanium, nickel, copper, palladium, silver, platinum, gold, lead, bismuth, germanium, silicon dioxide ($\textrm{SiO}_2$), alumina ($\textrm{Al}_2\textrm{O}_3$), tin-doped indium oxide (ITO), lead sulfide nanocrystals, the semiconducting polymers poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV), poly(3-hexylthiophene) (P3HT), and poly(benzimidazobenzophenanthroline ladder) (BBL), and the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS).Chemistry and Chemical Biolog