Surface modification of hydroxyapatite particles for biomaterial applications [abstract]

Abstract only availableThe interface between a filler material and a matrix can have a substantial impact on the properties of composites. This is especially true of nanoscale materials due to their increased ratio of surface area to mass. The goal of this research is to develop a method for modifying the surface of hydroxyapatite particles with nanometer scale features in order to improve the interaction between the particles and a polymer matrix that is widely employed in dental composites. This was done by adsorption of organic molecules onto the hydroxyapatite surface after nucleation. The results will serve as a guide for tailoring the surface chemistry of future nanomaterials to improve composites

Wheat-soybean double crop management in Missouri

"Double cropping soybeans after winter wheat has grown in popularity and feasibility in much of Missouri. This cropping system has several advantages. A crop, growing on the land all year, provides control of soil erosion. If you spread annual fixed costs such as land, taxes, and machinery over two crops instead of one, you increase gross returns per acre with relatively low increases in production costs. Thus, you can increase profits per acre. A successful wheat-soybean double crop depends on management and weather conditions. Establishing an adequate soybean stand and effective weed control are critical. In north Missouri, there are few days left in the season after wheat harvest for planting soybeans, and that's a constraint. So knowing the conditions to which doublecropping is best adapted will provide for a successful second crop. Also, it will enable you to avoid those years of high risk."--First page.Harry C. Minor, Zane R. Helsel, and Sean McCrate (Department of Agronomy, College of Agriculture)New 10/83/10

The Newfoundland and Labrador colorectal cancer screening program for the average risk population: A pre-implementation study of the family physician and target population perspective on fecal occult blood testing.

Background Newfoundland and Labrador (NL) has the highest incidence and mortality rates of colorectal cancer (CRC) in North America. In March 2010, funding was announced for a fecal occult blood test (FOBT) screening program for those aged 50 – 74 years and at average risk for CRC. The main goal of this program is to reduce mortality from CRC through the detection of pre-cancerous polyps or early-stage cancer. Research was undertaken prior to program implementation to survey the average risk population regarding their intention to participate in screening and to ascertain family physicians’ knowledge of screening guidelines, current screening practices and level of support for an organized screening program. Methods Average risk individuals living in three different areas of the province were surveyed (n = 959): a rural area with a familial cluster of high genetic risk CRC, and a rural and an urban area without familial clusters of high genetic risk CRC. It was hypothesized that those living in the area with a presence of high genetic risk CRC would be most likely to report positive intention to participate in screening. It was further hypothesized that between the two areas without any familial clustering of CRC, urban respondents would be more likely to report a positive intention to screen. The intent of the family physician survey (n = 274) was to enhance understanding of FOBT screening practices and level of physician support for an organized screening program. It was posited that the majority of physicians would be supportive of an organized FOBT screening program but would not necessarily be screening their average risk patients according to recommended guidelines. Results No significant association was found between intention to screen and a) presence of a familial cluster of high genetic risk CRC (p = 0.17), or b) residing in a rural versus urban region (p = 0.30). In multivariate analysis, prior awareness of FOBT [OR = 1.92, 95% CI 1.32 – 2.77, p = 0.001] and prior use of FOBT [OR = 1.87, 95% CI 1.18 – 2.97, p = 0.008] were significant predictors of positive screening intention. Almost all family physicians indicated support for an organized screening program (n = 256, 94.8%). Despite this, colonoscopy was the most commonly recommended procedure for screening average risk patients. Most physicians were compliant with the guideline- recommended age to start screening, (n = 228, 83.5%), but fewer were compliant with the recommended age for stopping (n = 66, 25%). Conclusions Presence of a familial cluster of high genetic risk CRC did not appear to positively impact the screening intention of average risk individuals. Based on previous research, a higher than expected level of positive intention to screen was reported across all regions that were sampled. Similarly, it was unanticipated that almost all family physicians would be supportive of an organized screening program. Follow-up research, post-implementation of the screening program, will provide an opportunity to determine whether reported intention and support translate into high rates of participation and physician referral for screening

Variação diária e espectral da atividade vocal de três espécies da família Tinamidae em florestas de terra firme da Amazônia brasileira

Birds are known to share information through conspicuous acoustic signals. Acoustic signals are especially important in habitats where vegetation makes long range visual signals ineffective. However, species that share similar characteristics of acoustic signals might also experience acoustic interference. Species that are closely related phylogenetically can also overlap in ecological and behavioral characteristics, enhancing the chance of acoustic interference. In order to avoid acoustic signal overlap, there might be present behavioral adaptations such as adjusting their vocal activity to avoid syntopic congeners. In this study, we used autonomous recording units (ARUs) to sample the dawn chorus activity of three species of tinamous (Family Tinamidae) during the dry season for two consecutive years at the Biological Dynamics of Forest Fragments Project in central Amazon, Brazil. We applied a method that accounts for imperfect detection in order to estimate the time of peak vocal activity for each species, while considering effects from the sampling bias. This study investigates how the species Tinamus major, Crypturellus variegatus and C. brevirostris utilize the acoustic space in time, and evaluate the degree of overlap in spectral and temporal traits of their calls. Our results suggests that these species use the acoustic space in a similarly, broadly overlapping in relation to the timing of vocal activity. However, these species differ significantly in characteristics of their calls. Our sampling and analytical methods had a temporal and spatial resolution that few bioacoustics studies have utilized; therefore we reinforce the body of publications which make use of ARUs and the usage of detection probabilities to better understand the dynamics of the dawn chorus.As aves comunicam-se principalmente através de sinais acústicos. Sinais acústicos são especialmente importantes em ambientes como a floresta amazônica, onde sinais visuais de longe alcance são impedidos pela vegetação. Sinais acústicos de espécies de aves que apresentam características espectrais semelhantes também podem sofrer com interferência acústica. Portanto, as aves devem repartir o espaço acústico que é finito. Para evitar à sobreposição espectral e/ou temporal as espécies adaptam suas vocalizações para utilizar frequências diferentes ou emitem sinais acústicos em diferentes momentos do coro matinal. Utilizamos gravadores autônomos para gravar o coro matinal durante duas estações de seca durante os anos de 2010 e 2011 no Projeto de Dinâmica Biológica de Fragmentos Florestais (PDBFF). Usamos estimativas das probabilidades de detecção ao longo da manhã de três espécies de aves da família Tinamidae ao longo do coro matinal. Este estudo investiga como as espécies Tinamus major, Crypturellus variegatus e C.brevirostris utilizam o espaço acústico e qual o nível de sobreposição temporal e espectral das atividades vocais. Nossos resultados indicam que estas espécies utilizam o espaço acústico de forma semelhante e há sobreposição temporal entre estas espécies. Demonstramos que a sobreposição temporal é maior que esperado ao acaso e que há diferenças significativas entre os parâmetros vocais analisados. Fizemos estimativas das probabilidades de detecções das três espécies ao longo do coro matinal para demonstrar que houve diferentes intensidades de sobreposição temporal da atividade vocal entre as três espécies. Nosso método utiliza uma resolução temporal e espacial ainda pouco utilizada para estudos bioacústicos, portanto nossos resultados reforçam que a utilização de gravadores autônomos é uma excelente ferramenta para futuros estudos de bioacústica

Higher-Order Methods for Determining Optimal Controls and Their Sensitivities

The solution of optimal control problems through the Hamilton-Jacobi-Bellman (HJB) equation offers guaranteed satisfaction of both the necessary and sufficient conditions for optimality. However, finding an exact solution to the HJB equation is a near impossible task for many optimal control problems. This thesis presents an approximation method for solving finite-horizon optimal control problems involving nonlinear dynamical systems. The method uses finite-order approximations of the partial derivatives of the cost-to-go function, and successive higher-order differentiations of the HJB equation. Natural byproducts of the proposed method provide sensitivities of the controls to changes in the initial states, which can be used to approximate the solution to neighboring optimal control problems. For highly nonlinear problems, the method is modified to calculate control sensitivities about a nominal trajectory. In this framework, the method is shown to provide accurate control sensitivities at much lower orders of approximation. Several numerical examples are presented to illustrate both applications of the approximation method

Molecular dynamics simulations of human [Formula: see text]: the role of modified bases in mRNA recognition

Accuracy in translation of the genetic code into proteins depends upon correct tRNA–mRNA recognition in the context of the ribosome. In human [Formula: see text] three modified bases are present in the anticodon stem–loop—2-methylthio-N6-threonylcarbamoyladenosine at position 37 (ms(2)t(6)A37), 5-methoxycarbonylmethyl-2-thiouridine at position 34 (mcm(5)s(2)U34) and pseudouridine (ψ) at position 39—two of which, ms(2)t(6)A37 and mcm(5)s(2)U34, are required to achieve wild-type binding activity of wild-type human [Formula: see text] [C. Yarian, M. Marszalek, E. Sochacka, A. Malkiewicz, R. Guenther, A. Miskiewicz and P. F. Agris (2000) Biochemistry, 39, 13390–13395]. Molecular dynamics simulations of nine tRNA anticodon stem–loops with different combinations of nonstandard bases were performed. The wild-type simulation exhibited a canonical anticodon stair-stepped conformation. The ms(2)t(6) modification at position 37 is required for maintenance of this structure and reduces solvent accessibility of U36. Ms(2)t(6)A37 generally hydrogen bonds across the loop and may prevent U36 from rotating into solution. A water molecule does coordinate to ψ39 most of the simulation time but weakly, as most of the residence lifetimes are <40 ps

Breast cancer surgical treatment choices in Newfoundland and Labrador, Canada: Patient and surgeon perspectives

Background. Breast cancer remains the second-leading cause of cancer death among Canadian women. Treatment for breast cancer often includes surgery. Many women have a choice between mastectomy (MT; removal of the entire breast) or breast conserving surgery (BCS; removal of the tumour and some noncancerous breast tissue) followed by radiation. However, Newfoundland and Labrador consistently has a higher rate of mastectomies than the rest of Canada. In this project, we aim to better understand that trend. Design and methods. A multi-method design was chosen. Surgical treatment data kept by the province will be examined to describe the number and types of breast cancer surgeries over time. Second, we will hold focus groups with women around the province who have made surgical treatment choices to explore influences on their decisions. Finally, semi-structured interviews with breast cancer surgeons and surgical residents will explore their opinions on surgical treatment choices. Expected impact for public health. Cancer treatment choices are complex decisions, affected by clinical, demographic and social variables. Understanding why women from Newfoundland and Labrador have the highest rate of mastectomy in Canada is critical to ensure they are receiving appropriate screening and care. Greater understanding of the influences on women’s surgical choices may encourage informed decisions amongst women and physicians and promote active communication about treatment, benefits relevant to all jurisdictions and health authorities. Further, if factors such as geographic proximity to treatment facilities are associated with treatment decisions, this information is important for public health screening and service planners

Graphene formation on SiC substrates

Graphene layers were created on both C and Si faces of semi-insulating, on-axis, 4H- and 6H-SiC substrates. The process was performed under high vacuum (<10-4 mbar) in a commercial chemical vapor deposition SiC reactor. A method for H2 etching the on-axis sub-strates was developed to produce surface steps with heights of 0.5 nm on the Si-face and 1.0 to 1.5 nm on the C-face for each polytype. A process was developed to form graphene on the substrates immediately after H2 etching and Raman spectroscopy of these samples confirmed the formation of graphene. The morphology of the graphene is described. For both faces, the underlying substrate morphology was significantly modified during graphene formation; sur-face steps were up to 15 nm high and the uniform step morphology was sometimes lost. Mo-bilities and sheet carrier concentrations derived from Hall Effect measurements on large area (16 mm square) and small area (2 and 10 um square) samples are presented and shown to compare favorably to recent reports.Comment: European Conference on Silicon Carbide and Related Materials 2008 (ECSCRM '08), 4 pages, 4 figure

An Investigation of Cancer Rates in the Argentia Region, Newfoundland and Labrador: An Ecological Study

Background. The Argentia region of Newfoundland and Labrador, Canada, was home to a US naval base during a 40-year period between the 1940s and the 1990s. Activities on the base resulted in contamination of the soil and groundwater in the region with chemicals such as heavy metals and dioxins, and residents have expressed concern about higher rates of cancer in their community. This study investigated the rate of cancer diagnosis that is disproportionately high in the Argentia region. Methods. Cases of cancer diagnosed between 1985 and 2011 were obtained for the Argentia region, two comparison communities, and the province of Newfoundland and Labrador. Crude and age-standardized incidence rates of cancer diagnosis were calculated and compared. The crude incidence rate was adjusted for differences in age demographics using census data, and age-standardized incidence rates were compared. Results. Although the Argentia region had a higher crude rate of cancer diagnosis, the age-standardized incidence rate did not differ significantly from the comparison communities or the provincial average. Argentia has an aging population, which may have influenced the perception of increased cancer diagnosis in the community. Conclusions. We did not detect an increased burden of cancer in the Argentia region