867 research outputs found

    Weather influences on demography of the yellow-bellied marmot (Marmota flaviventris)

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    Yellow-bellied marmots Marmota flaviventris were live-trapped and marked in the Ea-q River Valley of Colorado from 1962 to 1998. For females, static life tables were calculated each year from 1967, when ages were well known to 1997. Population density was determined, and from life tables calculations were made of. survivorship of young yearlings and adults, percentage of females producing litters; mean and variance of litter size: net reproductive rate(R-o); and generation length. From climate records a set of 14 annual weather variables was developed that described temperature, precipitation and lengths of growing season and winter. Data from 1981 and 1996 were not used since weather data contained extreme outliers in date of last snow cover. Univariate correlation matrices were calculated among weather variables, among demographic variables, and between weather and demographic variables. Mean temperature in 24 of 29 years was cooler than long-term average temperature. Generation length increased during the years of the study Weather data were used as independent variables with each dependent demographic variable to calculate nine multiple correlation and regression models. Models explained from 0% to 58% of the variation in demography. Significant factors in each model were mostly interpreted as affecting availability of energy necessary for successful hibernation and reproduction

    Are We Fulfilling the Promise of a Jesuit Education? A Group of Educators’ Reflective Examen

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    Higher education is often faced with external pressures that can guide the practice and offerings of colleges and universities. Graduate professional education in the health professions is especially prone to accreditation standards and its associated professional movements. At a Jesuit university, these external pressures, along with public pressure for job-ready graduates, must be intertwined with the history and the promise of a Jesuit education — that of transformation. As educators at a Jesuit university, our roles involve more than offering this kind of education. Our responsibility is to revisit what this promise means as a way of examining our practice. This article shares the reflective practice of five colleagues working in different roles at a Jesuit university seeking answers to questions of whether they are delivering on the promise of Jesuit education. The article includes a guiding set of questions, a short reflection on each author’s experience, and a review of the external and internal influences on their programs, providing a guide for a type of practice Examen that can be used by any faculty or staff member

    A 32-year demography of yellow-bellied marmots (Marmota flaviventris)

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    Yellow-bellied marmots Marmota flaviventris in the East River Valley of Colorado were live-trapped and individually marked annually from 1962 through 1993. These pooled data were used to produce a demography and life table for these years. Females had significantly better survivorship than males beyond the first-year age class, and the sex ratio became progressively female biased. The major mortality factors of predation and unsuccessful hibernation acted evenly on all age classes as shown by the constant rates of survivorship. The rate of senescence indicated that the probability of mortality did not increase with age. Females produced litters from ages 2 to 10 years. Mean litter size was 4.1 and did not differ among age classes. The female generation length of 4.49 years was 2.4 times the life expectancy and the median survivorship. The net reproductive rate (R-o) was 0.67, yet the population did not continually decline; adjustments to these data increased R-o to 0.85. Reproductive values (V-x) were approximately equal across the reproductive age classes. The polygynous mating system is both cause and effect of the demography. Marmot population size is affected by weather factors that influence reproduction and survival, by predation, and by movement into and out of the study area

    The effects of combined micron-/submicron-scale surface roughness and nanoscale features on cell proliferation and differentiation

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    Titanium (Ti) osseointegration is critical for the success of dental and orthopedic implants. Previous studies have shown that surface roughness at the micro- and submicro-scales promotes osseointegration by enhancing osteoblast differentiation and local factor production. Only relatively recently have the effects of nanoscale roughness on cell response been considered. The aim of the present study was to develop a simple and scalable surface modification treatment that introduces nanoscale features to the surfaces of Ti substrates without greatly affecting other surface features, and to determine the effects of such superimposed nano-features on the differentiation and local factor production of osteoblasts. A simple oxidation treatment was developed for generating controlled nanoscale topographies on Ti surfaces, while retaining the starting micro-/submicro-scale roughness. Such nano-modified surfaces also possessed similar elemental compositions, and exhibited similar contact angles, as the original surfaces, but possessed a different surface crystal structure. MG63 cells were seeded on machined (PT), nano-modified PT (NMPT), sandblasted/acid-etched (SLA), and nano-modified SLA (NMSLA) Ti disks. The results suggested that the introduction of such nanoscale structures in combination with micro-/submicro-scale roughness improves osteoblast differentiation and local factor production, which, in turn, indicates the potential for improved implant osseointegration in vivoTitanium (Ti) osseointegration is critical for the success of dental and orthopedic implants. Previous studies have shown that surface roughness at the micro- and submicro-scales promotes osseointegration by enhancing osteoblast differentiation and local factor production. Only relatively recently have the effects of nanoscale roughness on cell response been considered. The aim of the present study was to develop a simple and scalable surface modification treatment that introduces nanoscale features to the surfaces of Ti substrates without greatly affecting other surface features, and to determine the effects of such superimposed nano-features on the differentiation and local factor production of osteoblasts. A simple oxidation treatment was developed for generating controlled nanoscale topographies on Ti surfaces, while retaining the starting micro-/submicro-scale roughness. Such nano-modified surfaces also possessed similar elemental compositions, and exhibited similar contact angles, as the original surfaces, but possessed a different surface crystal structure. MG63 cells were seeded on machined (PT), nano-modified PT (NMPT), sandblasted/acid-etched (SLA), and nano-modified SLA (NMSLA) Ti disks. The results suggested that the introduction of such nanoscale structures in combination with micro-/submicro-scale roughness improves osteoblast differentiation and local factor production, which, in turn, indicates the potential for improved implant osseointegration in viv

    Differential responses of osteoblast lineage cells to nanotopographically-modified, microroughened titaniumealuminumevanadium alloy surfaces

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    Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications.Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy. The sensitivity of osteoblasts to both surface microroughness and nanostructures led to a synergistic effect on maturation and local factor production. Osteoblastic differentiation of MSCs was sensitive to TiAlV surface microroughness with respect to production of differentiation markers, but no further enhancement was found when cultured on micro/nanostructured surfaces. Superposition of nanostructures to microroughened surfaces affected final MSC numbers and enhanced production of vascular endothelial growth factor (VEGF) but the magnitude of the response was lower than for HOB cultures. Our results suggest that the differentiation state of osteoblast-lineage cells determines the recognition of surface nanostructures and subsequent cell response, which has implications for clinical evaluation of new implant surface nanomodifications

    Spacecraft Charging Test Considerations for Composite Materials

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    Composite materials present a growing challenge for spacecraft charging assessments. We review some recent lessons learned for charging tests of composite materials using both parallel-plate and electron beam test geometries. We also discuss examples of materials that exhibit significant variations between samples, despite them all having the same trade name

    Role of a2b1 integrins in mediating cell shape on microtextured titanium surfaces

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    Surface microroughness plays an important role in determining osteoblast behavior on titanium. Previous studies have shown that osteoblast differentiation on microtextured titanium substrates is dependent on alpha-2 beta-1 (a2b1) integrin signaling. This study used focused ion beam milling and scanning electron microscopy, combined with three-dimensional image reconstruction, to investigate early interactions of individual cells with their substrate and the role of integrin a2b1 in determining cell shape. MG63 osteoblast-like cells on sand blasted/acid etched (SLA) Ti surfaces after 3 days of culturing indicated decreased cell number, increased cell differentiation, and increased expression of mRNA levels for a1, a2, aV, and b1 integrin subunits compared to cells on smooth Ti (PT) surfaces. a2 or b1 silenced cells exhibited increased cell number and decreased differentiation on SLA compared to wild-type cells. Wild-type cells on SLA possessed an elongated morphology with reduced cell area, increased cell thickness, and more apparent contact points. Cells on PT exhibited greater spreading and were relatively flat. Silenced cells possessed a morphology and phenotype similar to wild-type cells grown on PT. These observations indicate that surface microroughness affects cell response via a2b1 integrin signaling, resulting in a cell shape that promotes osteoblastic differentiation. VC 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 564–573, 2015.Surface microroughness plays an important role in determining osteoblast behavior on titanium. Previous studies have shown that osteoblast differentiation on microtextured titanium substrates is dependent on alpha-2 beta-1 (a2b1) integrin signaling. This study used focused ion beam milling and scanning electron microscopy, combined with three-dimensional image reconstruction, to investigate early interactions of individual cells with their substrate and the role of integrin a2b1 in determining cell shape. MG63 osteoblast-like cells on sand blasted/acid etched (SLA) Ti surfaces after 3 days of culturing indicated decreased cell number, increased cell differentiation, and increased expression of mRNA levels for a1, a2, aV, and b1 integrin subunits compared to cells on smooth Ti (PT) surfaces. a2 or b1 silenced cells exhibited increased cell number and decreased differentiation on SLA compared to wild-type cells. Wild-type cells on SLA possessed an elongated morphology with reduced cell area, increased cell thickness, and more apparent contact points. Cells on PT exhibited greater spreading and were relatively flat. Silenced cells possessed a morphology and phenotype similar to wild-type cells grown on PT. These observations indicate that surface microroughness affects cell response via a2b1 integrin signaling, resulting in a cell shape that promotes osteoblastic differentiation. VC 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 564–573, 2015

    San Giovanni Laterano Studio Project, Syracuse University School of Architecture Florence Program (1983)

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    This publication is the result of one semester\u27s design work from the Syracuse University Florence Program. Our purpose in compiling this material is two-fold; in presenting this work as an example of the design activity that occurs at the Florence Center, we intend to reveal the unique opportunity that this Program offers to students from the United States. In addition, we are using this vehicle to address the in­tellectual context within which our students worked during their design process. Giuseppe Vallifuoco and Sergio Petrini (Roman architects and our Visiting Critics) presented a specific bias toward the produc­tion of architecture, and we feel that an explication of their concerns can contribute to an understanding of current architectural activity in Italy
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