8,911 research outputs found
PRIMER REGISTRO DE ISCHNODERMA RESINOSUM (SCHRAD.) P. KARST. Y TYROMYCES FISSILIS (BERK. & M.A. CURTIS) DONK (POLYPORALES, BASIDIOMYCOTA) EN MÉXICO
No full textSe registran y describen por primera vezpara México a Ischnoderma resinosum(Schrad.) P. Karst., encontrada en Guerreroy Tyromyces fissilis (Berk. & M.A. Curtis)Donk del Estado de México. Los ejemplaresestán depositados en los herbarios ENCBy FCME.Se registran y describen por primera vezpara México a Ischnoderma resinosum(Schrad.) P. Karst., encontrada en Guerreroy Tyromyces fissilis (Berk. & M.A. Curtis)Donk del Estado de México. Los ejemplaresestán depositados en los herbarios ENCBy FCME
Primer registro de Ischnoderma resinosum (Schrad.) P. Karst. y Tyromyces fissilis (Berk. & M.A. Curtis) Donk (Polyporales, Basidiomycota) en México
No full textIschnoderma resinosum (Schrad.) P. Karst., founded in Guerrero and Tyromyces fissilis (Berk. & M.A. Curtis) Donk from Estado de México are described and recorded first time to Mexico, specimens boucher are in ENCB and FCME herbaria.Se registran y describen por primera vez para México a Ischnoderma resinosum (Schrad.) P. Karst., encontrada en Guerrero y Tyromyces fissilis (Berk. & M.A. Curtis) Donk del Estado de México. Los ejemplares están depositados en los herbarios ENCB y FCME
PRIMER REGISTRO DE ISCHNODERMA RESINOSUM (SCHRAD.) P. KARST. Y TYROMYCES FISSILIS (BERK. & M.A. CURTIS) DONK (POLYPORALES, BASIDIOMYCOTA) EN MÉXICO
No full textSe registran y describen por primera vez
para México a Ischnoderma resinosum
(Schrad.) P. Karst., encontrada en Guerrero
y Tyromyces fissilis (Berk. & M.A. Curtis)
Donk del Estado de México. Los ejemplares
están depositados en los herbarios ENCB
y FCME
Curtis Hunsaker
No full textCurtis B. Hunsaker, received in M.A. degree at BYU. He earned his degree by attending summer school for six years. He has taught at the Vernal Seminary for the past eight years. He is the husband of Carma Weeks
mollis
No full textThermopsis mollis (Michaux) M.A. Curtisadjacent to old railroad right-of-way, Northamptonthickety area, adjacent to old railroad right-of-wa
Seagrasses in Port Curtis and Rodds Bay 2016: annual long-term monitoring
No full textIn 2016, seagrasses in Port Curtis and Rodds Bay remained in an overall poor condition. The results for individual meadows and regions however, were mixed, with some meadows improving in condition and others declining since 2015.
There was no clear relationship between distance from anthropogenic activities and seagrass condition, with many of the meadows in improved condition closest to port activity and some areas furtherest away experiencing declines.
It is important to note that meadows can be classified as being in poor condition if any one of the three key indicators (biomass; area; species composition) were poor, even if the other two indicators had improved. For some meadows this was the case in 2016, especially those that had started to recover from recent declines with the key species yet to return.
Of most concern was the significant decline in biomass for the largest and most stable seagrass meadow in the Port Curtis region, Pelican Banks. This meadow between Curtis and Facing Islands was in very poor condition in 2016 with the lowest ever recorded biomass, smallest area and a decline in the make-up of species.
The reasons for the decline in this substantial area of seagrass are unclear. Monitoring of light and climate drivers showed a generally favourable environment for seagrass growth in 2016. There are a range of potential contributors to the decline of this meadow. High levels of herbivory from dugong and turtle, movement of sediments on banks, and the range of repeated disturbances from climate, floods, cyclones and anthropogenic activities offer possible explanations but require further investigation.
Seagrasses in the out of port reference area at Rodds Bay also deteriorated in 2016 and were found to be in a very poor condition. These meadows have been in a poor state since substantial declines between 2008 and 2009.
Dugong continue to make use of seagrasses throughout the Port Curtis and Rodds Bay area including areas of high port and industrial activity.
Resilience of seagrasses in Port Curtis to further natural or anthropogenic impacts is likely to be low. In 2016, seed banks remained in key meadows and some seagrass was maintained across most of the historical extent of seagrass distribution. However, both were at substantially reduced levels. Climate and weather conditions during 2017 will play a critical role in determining the trajectory of seagrass change
DS_10.1177_0022034519877150 – Supplemental material for Horizontal and Vertical Transfer of Oral Microbial Dysbiosis and Periodontal Disease
No full textSupplemental material, DS_10.1177_0022034519877150 for Horizontal and Vertical Transfer of Oral Microbial Dysbiosis and Periodontal Disease by M.A. Payne, A. Hashim, A. Alsam, S. Joseph, J. Aduse-Opoku, W. Wade and M.A. Curtis in Journal of Dental Research</p
Port Curtis Seagrass Seed Bank Density and Viability Studies - final report
No full textSeagrass seeds and seed banks (seeds stored in sediments) are important in maintaining seagrass populations and their capacity to recover from impacts. Despite their importance, longer-term studies incorporating assessments of seed bank viability are rare and we have little information on how seed banks vary temporally or spatially in their distribution and viability, particularly for tropical and sub-tropical species. This study provides important insights into the seasonal and inter-annual changes in seed bank density and viability, and the implications for local seagrass resilience in Port Curtis and Rodds Bay. The results add substantially to the current knowledge of seagrass seed bank dynamics.
The report details findings from a three year study examining seed bank dynamics for the seagrass Zostera muelleri subsp. capricorni in Port Curtis and Rodds Bay. Results show that a Z. muelleri seed bank was generally present across all sites and times examined, however, temporal trends in seed bank density differed between sites and did not always follow expected seasonal patterns. In addition, viability assessments found that the available seed bank was substantially lower than total seed numbers would suggest, and at times, some sites had no viable seeds present. Viable seeds tended to be located deeper below the sediment surface potentially making them less available for germination and the proportion of the total seed bank that was viable varied considerably between and within sites and over time.
The study highlights the complexity of seed bank dynamics in Port Curtis and Rodds Bay and demonstrates that quantifying resilience requires moving beyond counting densities of seeds to including temporal measurements of seed bank viability. The results provide evidence for the presence of viable seed banks throughout the three year study that are likely to play an important role in conferring resilience to local seagrass meadows. The presence of viable seeds in meadows where no local seed production had been recorded for several years indicates that dispersal of propagules between meadows and sites was likely to be an important process in shaping Port Curtis and Rodds Bay seed banks.
The maintenance of some viable seeds throughout the study meant Port Curtis Z. muelleri meadows were well placed to deal with large-scale impacts and had a pathway to recover from meadow scale losses if these viable seeds were to germinate. However, a substantial decline in viable seeds at the end of the program in 2017 was concerning, particularly if seed banks are not replenished during the 2017 seagrass growing season. This result combined with record lows in area and abundance for the largest Z. muelleri meadow in Port Curtis suggests that at the end of the study, levels of resilience for some Port Curtis and Rodds Bay meadows were reduced.
The results of this study provide a strong case for the inclusion of assessments of the seed bank that incorporate viability assessment as part of routine seagrass monitoring programs. The low and variable proportion of total seed numbers that were actually viable show that total seed counts alone, will not necessarily provide a true understanding of the state of seed banks. Quantifying these seed bank dynamics is particularly important to gain a clear picture of seagrass meadow resilience given that losses of seagrasses at meadow or larger scales will be reliant on seeds for their recovery
Deep anisotropic dry etching of silicon microstructures by high-density plasmas
No full textThis thesis deals with the dry etching of deep anisotropic microstructures in monocrystalline silicon by high-density plasmas. High aspect ratio trenches are necessary in the fabrication of sensitive inertial devices such as accellerometers and gyroscopes. The etching of silicon in fluorine-based plasmas is isotropic. To obtain anisotropy the addition of sidewall passivation is necessary. This is achieved with both oxygen passivation at low temperatures and fluorocarbon passivation at room temperature. A quantitative approach was pursued to explain the etching mechanism. The etch results were analysed using the measured plasma species fluxes and the surface composition. Moreover, the transport of the plasma species in narrow anisotropic structures is a fundamental factor determining the etch rate and the profile evolution. The experimental methods such as the etching equipment, plasma diagnostics, surface analysis and sample preparation are described in chapter 2. Three etching processes were investigated: the cryogenic etching process with oxygen passivation at low temperatures, the Bosch process with fluorocarbon passivation at room temperature and the novel triple pulse process that was developed in our laboratory. The polymer deposition mechanism and the characteristic role of the ions are also explained. The cryogenic etching process is discussed in chapter 3. Fluorine radicals, oxygen radicals and ion bombardment are responsible for the three main sub-processes, that is, etching, sidewall passivation and depassivation of the trench bottom, respectively. Etching experiments with an extremely low ion-to-radical flux ratio were used to reveal the etching mechanism. Crystal orientation dependent etching leading to Si(111) crystal facets is observed in a surface kinetics controlled regime. By varying the plasma conditions it is possible to adjust the etching mechanism from fluorine-limited to ion-limited. Controlled etching is obtained because the etching is tuned from aspect ratio dependent in the fluorine-limited domain to aspect ratio independent in the ion-limited domain. The transport of radicals in high aspect ratio trenches is an important limiting factor and was investigated with special structures. The etch results are described by an analytic model that is based on the surface site balance of fluorine and oxygen radicals. The results are further explained with a Monte Carlo simulation model. The Bosch process is clarified in chapter 4. The anisotropy of the etched structures is controlled by balancing the etching and passivation pulse. However, the maximal obtainable aspect ratio is limited by convergence of the trench sidewalls due to excessive passivation. The maximal obtainable aspect ratio increases if the ion-to-radical flux ratio increases. The transport of ions is an important limiting factor in the depassivation of the bottom of the trench. Divergence of the ion beam leads to a reduction of the ion flux, so that the fluorocarbon passivation is insufficiently removed near the base of the sidewalls. The average ion angle was measured and correlated to the maximal obtainable aspect ratio. The Bosch process was improved at the depassivation side with the triple pulse process and at the passivation side with preferential sidewall deposition. The triple pulse process that is described in chapter 5 has the aim to improve the depassivation in deep trenches. The three main sub-processes are decoupled using a separate depassivation pulse directly after the etching and passivation pulses. The fluorocarbon passivation is efficiently removed with low-pressure, high-density, oxygen-based plasmas. The investigated plasma chemistries include O2, CO2 and SO2. The triple pulse process leads to better profile control with a straight trench bottom. However, the maximal obtainable aspect ratio is comparable to the Bosch process because a larger etch depth and a small lateral etch cancel out. The polymer deposition mechanism is treated in chapter 6 with the aim to understand the fluorocarbon passivation in deep trenches. The deposition on plane surfaces and on special structures was investigated to distinguish between the radical-induced and ion-enhanced components. A simple analytical model, which explains the main deposition characteristics, was developed. Preferential sidewall deposition is obtained for higher ion fluxes and higher bias voltages where sputtering plays an important role. In this case no fluorocarbon passivation has to be removed from the bottom of the trench. The trench profile was optimised in the Bosch process by tuning the bias voltage during etching and passivation independently. It resulted in perfectly anisotropic trenches but the maximal obtainable aspect ratio was still limited by a small lateral etch. The characteristic role of the ions in the etching mechanism is explained in chapter 7. Ion-induced etching of both SiC in a SF6-O2 plasma and Si in a Cl2 plasma were investigated. The impact of the ions on the profile evolution can be examined more explicitly because spontaneous chemical reactions are absent for these plasma-material systems. The etching mechanism varies from fluorine-limited to ion-limited depending on the radical-to-ion flux ratio. Microtrenches are observed for an ion-limited etching mechanism. Fluorine-limited SiC etching is aspect ratio dependent in contrast to ion-limited SiC etching, which is aspect ratio independent. The etching of high aspect ratio SiC structures is limited by the positive sidewall taper. This is presumably caused by insufficient removal of the thin fluorocarbon layer on the surface. Si etching in a Cl2 plasma is always aspect ratio independent in contrast to SiC etching because of the low reaction probability. The conclusions and recommendations of this thesis are given in chapter 8.Applied Science
AVALIAÇÃO DE MÉTODOS PARA PRESERVAÇÃO DE ISOLADOS DE Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei
No full textCorynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei is the causal agent for target spot on several economically important crops. So, studies on the C. cassiicola isolates preservation are necessary to maintain mycelium growth and sporulation, during experiments. The objective of this study was to evaluate the efficiency of three isolates preserving methods: Castellani, periodical transference, and mineral oil, during six months of storage. The evaluations were carried out by analyzing mycelial growth on potato-dextrose-agar medium. It was observed that mycelial growth was higher in the periodical transference method, sporulation was a little higher in the Castellani method, and all methods preserved isolates pathogenicity. Thus, for that phythopatogen, the Castellani method is the most recommended one.O fungo Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei é o agente causal da mancha alvo, em diversas culturas de importância econômica. Assim, estudos de preservação de isolados de C. cassiicola, que possam manter viáveis isolados do patógeno, durante experimentos, são necessários. O objetivo deste trabalho foi testar a eficiência de três métodos de preservação de isolados: Castellani, repicagens periódicas e óleo mineral, durante seis meses de armazenamento. As avaliações foram efetuadas por meio de análise do desenvolvimento do fungo, em meio de cultivo contendo batata-dextrose-ágar. Constatou-se que o crescimento micelial foi maior para o método de repicagens periódicas; a esporulação, no método Castellani, foi um pouco superior à dos demais métodos; e todos os métodos propiciaram a preservação da patogenicidade dos isolados estudados. Desta forma, recomenda-se, para este fitopatógeno, o método de preservação Castellani
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