389 research outputs found

    Pointwise Bounds and Blow-up for Systems of Semilinear Elliptic Inequalities at an Isolated Singularity via Nonlinear Potential Estimates

    Full text link
    We study the behavior near the origin of C2C^2 positive solutions u(x)u(x) and v(x)v(x) of the system 0≀−Δu≀f(v)0\leq -\Delta u\leq f(v) 0≀−Δv≀g(u)0\leq -\Delta v\leq g(u) in B1(0)\{0}B_1(0)\backslash\{0\} where f,g:(0,∞)→(0,∞)f,g:(0,\infty)\to (0,\infty) are continuous functions. We provide optimal conditions on ff and gg at ∞\infty such that solutions of this system satisfy pointwise bounds near the origin. In dimension n=2n=2 we show that this property holds if log⁥+f\log^+ f or log⁥+g\log^+g grow at most linearly at infinity. In dimension n≄3n\geq 3 and under the assumption f(t)=O(tλ)f(t)=O(t^\lambda), g(t)=O(tσ)g(t)=O(t^\sigma) as t→∞t\to \infty, (λ,σ≄0\lambda, \sigma\geq 0), we obtain a new critical curve that optimally describes the existence of such pointwise bounds. Our approach relies in part on sharp estimates of nonlinear potentials which appear naturally in this context.Comment: 41 pages, 1 figur

    The Hip Center Rule Can be Used to Decide if Measured Pelvic Incidence is Accurate

    Get PDF
    STUDY DESIGN: Simulation study. OBJECTIVE: Pelvic incidence (PI) should be considered during surgical planning. The ideal patient position with both hip centers perfectly aligned for a lateral radiograph is rarely obtained. It has been suggested that a radiograph with axial and coronal rotation up to 20° is acceptable to obtain a measured PI within 6 degrees of the actual PI. We seek to: (1) evaluate the effect of variations in PI and patient malpositioning on measured vs true PI, and (2) determine whether the presence of one hip center within the bony acetabular rim of the contralateral hip can serve as a simple clinical decision rule on the accuracy of measured PI. METHODS: Published anthropometric three-dimensional pelvic landmark coordinates were used in this study. Radiographic projections were generated using linear algebra for combinations of axial and coronal rotation from -20° to +20°. True and measured PIs were compared. RESULTS: Rotation to 20° cannot be uniformly accepted as decision rule. Pelvises with higher PIs are more sensitive to malpositioning with greater PI deviation with smaller amounts of rotation. Diagnostic performance of the hip center rule demonstrated a sensitivity of 25.58% and a specificity of 100.00%. CONCLUSIONS: Rather than assessing the quality of radiographs for PI measurement by magnitude of malpositioning, we recommend clinicians use the hip center rule. As long as at least one hip center is contained within the bony acetabular rim of the contralateral hip, there is high confidence that measured PI will be within 6° of true PI

    Changes in Sr/Ca, Ba/Ca and 87Sr/86Sr ratios between trophic levels in two forest ecosystems in the northeastern U.S.A.

    Full text link
    The variability and biologicalfractionation of Sr/Ca, Ba/Ca and 87 Sr/ 86 Srratios were studied in a soil–plant–invertebrate–bird food chain in two forested ecosystems withcontrasting calcium availability in the northeasternU.S.A. Chemical measurements were made of the soilexchange pool, leaves, caterpillars, snails, and boththe femurs and eggshells of breeding insectivorousmigratory songbirds. 87 Sr/ 86 Sr values weretransferred up the food chain from the soil exchangepool to leaves, caterpillars, snails and eggshellswithout modification. Adult birds were the oneexception; their 87 Sr/ 86 Sr values generallyreflected those of lower trophic levels at each site,but were lower and more variable, probably becausetheir strontium was derived in part from foods intropical winter habitats where lower 87 Sr/ 86 Sr ratios are likely to predominate. Sr/Ca and Ba/Ca ratios decreased at each successive trophiclevel, supporting previous suggestions that Sr/Ca andBa/Ca ratios can be used to identify the trophic levelat which an organism is primarily feeding. The changesin Sr/Ca and Ba/Ca ratios we measured for vegetationand insects were comparable to similar measurementsmade previously (but based on single samples of eachorganism) in an alpine ecosystem. Changes in Sr/Ca andBa/Ca ratios between birds and their food have notpreviously been measured, but the values we obtainedwere similar to those for herbivorous and carnivorousmammals at similar trophic levels. Our results provideevidence that supports the use of Sr/Ca ratios in thedetermination of human paleodiets and suggests thatSr/Ca ratios may also provide a useful tool in studiesof modern food webs. Furthermore, our findings suggestthat 90 Sr from nuclear fallout will notbioaccumulate in forests and that changes in Sr/Caratios between trophic levels will need to beconsidered in some cases when using 87 Sr/ 86 Sr as a tracer of calciumbiogeochemistry.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42474/1/10533_2004_Article_240599.pd

    Latitudinal and Longitudinal Adaptation of Switchgrass Populations

    Get PDF
    Switchgrass (Panicum virgatum L.) is a warmseason native grass, used for livestock feed, bioenergy, soil and wildlife conservation, and prairie restoration in a large portion of the USA. The objective of this research was to quantify the relative importance of latitude and longitude for adaptation and agronomic performance of a diverse group of switchgrass populations. Six populations, chosen to represent remnant prairie populations on two north–south transects, were evaluated for agronomic traits at 12 locations ranging from 36 to 47°N latitude and 88 to 101°W longitude. Although the population × location interactions accounted for only 10 to 31% of the variance among population means, many significant changes in ranking and adaptive responses were observed. Ground cover was greater for northern-origin populations evaluated in hardiness zones 3 and 4 and for southern-origin populations evaluated in hardiness zones 5 and 6. There were no adaptive responses related to longitude (ecoregion). Switchgrass populations for use in biomass production, conservation, or restoration should not be moved more than one hardiness zone north or south from their origin, but some can be moved east or west of their original ecoregion, if results from field tests support broad longitudinal adaptation

    Psychometric Evaluation of the Arabic Version of the Spiritual Well-Being Scale on a Sample of Jordanian Arab Christians

    Get PDF
    This paper assesses the psychometric properties of the Arabic version of the Spiritual Well-Being Scale (SWBS) in an Arab Christian sample by analyzing its internal structure. A convenience sample of 340 Arab Christians was recruited from the adult community population of northern Jordan. Data were collected through a self-completion, anonymous questionnaire distributed through church and community groups. Principal Components factor analysis, non-parametric bivariate statistics, and Cronbach's alpha were used to assess the psychometric properties of the total scale and its subscales. The findings broadly supported the factor structure of the SWBS in other Arab samples in that the scale consists of three factors, representing positive existential well-being, affiliation, and alienation subscales. In conclusion, these preliminary findings suggest that the Arabic version of the SWBS can be used as an instrument to measure levels of spiritual well-being in Arab Christian populations. </jats:p

    Prevalence of self-harm among lesbian, gay, bisexual, and transgender adolescents: a comparison of personal and social adversity with a heterosexual sample in Ghana

    Get PDF
    Objectives We sought to estimate the prevalence of self-reported self-harm among adolescents identifying as lesbian, gay, bisexual, and transgender (LGBT) in Ghana, and compare self-reported personal and social adversities related to self-harm in this group to those in a random sample of heterosexual adolescents from the same locality. Results A total of 444 adolescents aged 13-21 years, comprising 74 LGBT adolescents and 370 heterosexual adolescents, provided data. The lifetime prevalence estimate of self-harm was higher in the LGBT group (47%) than the heterosexual group (23%). The LGBT group reported a higher rate of self-harm during the previous 12 months (45%), compared to the heterosexual group (18%). LGBT adolescents reported more alcohol and substance use and more personal social adversities, including various forms of victimisation, than heterosexual adolescents. They were no more likely to report difficulty in making and keeping friends or schoolwork problems than were heterosexual adolescents

    How to Build Collective Capabilities: The 3C-Model for Grassroots-led Development

    Get PDF
    Capabilities need to be built from the bottom-up. Social innovations at the grassroots seek to present new solutions to existing social problems. However, since the poor suffer from limitations on their individual capabilities and agency, they engage in acts of collective agency to generate new collective capabilities that each individual alone would not be able to achieve. The question is: how can these acts of collective agency be initiated, supported and sustained in practice? What roles can development actors (such as the state, donors and NGOs) play in supporting these acts of collective agency? Drawing on the literature on social innovation, the capability approach, participation and empowerment, the paper argues that three crucial C-processes are integral conditions for promoting successful, scalable and sustainable social innovations at the grassroots, namely: (1) Conscientization; (2) Conciliation and (3) Collaboration. By linking the individual, collective and institutional levels of analysis, the paper demonstrates the importance of individual behavioural changes, collective agency and local institutional reforms for the success, sustainability and scalability of social innovations at the grassroots. The paper acknowledges conflict, capture and cooptation as potential limitations and recognizes the role of contextual factors in initiating, implementing and sustaining social innovations at the grassroots

    Nuclear role for human Argonaute-1 as an estrogen-dependent transcription coactivator

    Get PDF
    In mammals, argonaute (AGO) proteins have been characterized for their roles in small RNA mediated posttranscriptional and also in transcriptional gene silencing. Here, we report a different role for AGO1 in estradiol-triggered transcriptional activation in human cells. We show that in MCF-7 mammary gland cells, AGO1 associates with transcriptional enhancers of estrogen receptor α (ERα) and that this association is up-regulated by treating the cells with estrogen (E2), displaying a positive correlation with the activation of these enhancers.Moreover, we show that AGO1 interacts with ERα and that this interaction is also increased by E2 treatment, but occurs in the absence of RNA. We show that AGO1 acts positively as a coactivator in estradiol-triggered transcription regulation by promoting ERα binding to its enhancers. Consistently, AGO1 depletion decreases long-range contacts between ERα enhancers and their target promoters. Our results point to a role of AGO1 in transcriptional regulation in human cells that is independent from small RNA binding.Fil: Gómez Acuña, Luciana Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Nazer, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Rodríguez Seguí, Santiago Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Pozzi, María Berta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Buggiano, Valeria Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Marasco, Luciano Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Agirre, Eneritz. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: He, Cody. University of Chicago; Estados UnidosFil: Alló, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Kornblihtt, Alberto Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin
    • 

    corecore