494 research outputs found

    A pilot study on the nanoscale properties of bone tissue near lacunae in fracturing women

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    The goal of this study is to investigate the causes of osteoporosis-related skeletal fragility in postmenopausal women. We hypothesize that bone fragility in these individuals is largely due to mineral, and/or intrinsic material properties in the osteocyte lacunar/peri-lacunar regions of bone tissue. Innovative measurements with nanoscale resolution, including scanning electron microscope (SEM), an atomic force microscope that is integrated with infrared spectroscopy (AFM-IR), and nanoindentation, were used to characterize osteocyte lacunar and peri-lacunar properties in bone biopsies from fracturing (Cases) and matched (Age, BMD), non-fracturing (Controls) postmenopausal healthy women. In the peri-lacunar space, the nanoindentation results show that the modulus and hardness of the Controls are lower than the Cases. The AFM-IR results conclusively show that the mineral matrix, maturity (peak) (except in outer/far regions in Controls) were greater in Controls than in Cases. Furthermore, these results indicate that while mineral-to-matrix area ratio tend to be greater, the mineral maturity and crystallinity peak ratio “near” lacunae is greater than at regions “far” or more distance from lacunae in the Controls only. Due to the heterogeneity of bone structure, additional measurements are needed to provide more convincing evidence of altered lacunar characteristics and changes in the peri-lacunar bone as mechanisms related to postmenopausal women and fragility. Such findings would motivate new osteocyte-targeted treatments to reduce fragility fracture risks in these groups

    Etching of random solids: hardening dynamics and self-organized fractality

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    When a finite volume of an etching solution comes in contact with a disordered solid, a complex dynamics of the solid-solution interface develops. Since only the weak parts are corroded, the solid surface hardens progressively. If the etchant is consumed in the chemical reaction, the corrosion dynamics slows down and stops spontaneously leaving a fractal solid surface, which reveals the latent percolation criticality hidden in any random system. Here we introduce and study, both analytically and numerically, a simple model for this phenomenon. In this way we obtain a detailed description of the process in terms of percolation theory. In particular we explain the mechanism of hardening of the surface and connect it to Gradient Percolation.Comment: Latex, aipproc, 6 pages, 3 figures, Proceedings of 6th Granada Seminar on Computational Physic

    The Ursinus Weekly, April 11, 1949

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    Censorship cancels April fool issue • Debaters finish second in Ben Franklin tourney • Terror and humor to occupy evening of thespian talent • Weekly editors cancel year\u27s plans following last minute faculty demand • Betty Rilling pens winning May script for Ursinus coeds • Imre Kovacs urges Christian standards in Tuesday address • Should faculty exert control on Weekly ? • R. Mack named Bus Ad prexy; Gradwohl, McMillan get offices • Magazine names Ursinus in list of representative good colleges • Athletic Association to present annual minstrel show April 19 • Drummer and Schultz selected as headwaiters for coming year • Weekly offers fin to author of letter • Gaff , poll voted most controversial • Curtis scores close win in gala intramural night • Dennis named head of 1950 golf team; six matches carded • Softball belles aim to maintain record as five vets return • Fifteen man squad lifts coach\u27s hopes for winning season • Cox bows in AAU quarter-finals; Fords trip bruin nine 2-0 • Track vets sparkle in practice session with West Chester • Haverford\u27s Heberton hurls two-hitter; error costly for pitcher Ron Landes • Two letter winners, hopeful rookies vie for coed net spots • Coeds end schedule with decisive wins in hoop, pool tilts • Tischler, Harris cop leads in spring play • New \u27Weekly\u27 heads to be introduced at annual banquethttps://digitalcommons.ursinus.edu/weekly/1613/thumbnail.jp

    Dynamics of fermions coupling to a U(1) gauge field in the limit e2e^2\to\infty

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    We study in this paper the properties of a gas of fermions coupling to a U(1) gauge field at wavevectors q<Λ<<kFq<\Lambda<<k_F at dimensions larger than one, where Λ<<kF\Lambda<<k_F is a high momentum cutoff and kFk_F is the fermi wave vector. In particular, we shall consider the e2e^2\to\infty limit where charge and current fluctuations at wave vectors q<Λq<\Lambda are forbidden. Within a bosonization approximation, effective actions describing the low energy physics of the system are constructed, where we show that the system can be described as a fermion liquid formed by chargeless quasi-particles which has vanishing wavefunction overlap with the bare fermions in the system.Comment: 25 page

    UJI KARAKTERISTIK SIFAT FISIK, KIMIA DAN ORGANOLEPTIK PADA KUE TRADISIONAL KU’U DARI TEPUNG UBI TALAS

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    Mensubstitusi tepung talas pada pembuatan kue Ku'u dapat memberikan variasi baru pada olahan kue Ku'u, meningkatkan pemakaian bahan pangan lokal dan minat masyarakat untuk mencintai hasil pertanian lokal serta sekaligus dapat mengurangi kebutuhan akan tepung terigu impor. Tujuan dari penelitian ini yaitu untuk mengetahui hasil uji organoleptik dan hasil uji serat kue tradisinal ku’u tersubtitusi tepung umbi talas. Proses pembuatan tepung hingga kue tradisional Ku’u meliputi pencucian, pengupasan, pengirisan, pengeringan, penggilingan, pengayakan. Dilanjutkan dengan pembuatan kue Ku’u yaitu pencampuran bahan, penambahan warna makanan, diaduk, dicetak, memasukkan isian unti kelapa, dilapisi dengan daun pandan, pengukusan kue Ku’u. Metode yang dilakukan adalah metode Rancangan Acak Lengkap (RAL) dengan 3 perlakuan dan 3 ulangan. Pada uji organoleptik, Rasa, warna, aroma dan tekstur memiliki hasil yang berbeda nyata dan signifikan antra satu sama lain

    Comparative life cycle assessment of LED lighting products

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    LED lighting products used in lighting applications and their subsequent environmental impact are growing rapidly. However, there are no in-depth updated studies that show how to assess and compare them for eco-design purposes. This research aims to add insights in this area to inform eco-design by assessing and comparing the environmental impact of a new LED eco-lighting product with an existing LED lighting product. A cradle to grave Life Cycle assessment (LCA) was conducted using ReCiPe Midpoint and Endpoint (H) life cycle impact assessment method with Simapro software. The system boundaries included all product life cycle stages, except the maintenance of the luminaires and the manufacturing of the packaging. A novel functional unit was defined for the assessment, which is more suitable for the LED lighting products. Six scenarios were considered, including three probable useful lives of the luminaires (1,000, 15,000 and 40,000 h) and two end of life options (domestic bin and recycling centre). The LCA results revealed that the new eco-lighting product has about 60% less environmental impact than the existing lighting product in all scenarios. The life cycle stages with the highest environmental impact are: 1) Use, 2) Manufacturing, 3) End of Life and 4) Transport. Based on the results obtained, recommendations for eco-design of LED lighting products were proposed, and challenges of application of LCA for the eco-design were discussed

    Defining freshwater as a natural resource: a framework linking water use to the area of protection natural resources

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    © 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: While many examples have shown unsustainable use of freshwater resources, existing LCIA methods for water use do not comprehensively address impacts to natural resources for future generations. This framework aims to (1) define freshwater resource as an item to protect within the Area of Protection (AoP) natural resources, (2) identify relevant impact pathways affecting freshwater resources, and (3) outline methodological choices for impact characterization model development. Methods: Considering the current scope of the AoP natural resources, the complex nature of freshwater resources and its important dimensions to safeguard safe future supply, a definition of freshwater resource is proposed, including water quality aspects. In order to clearly define what is to be protected, the freshwater resource is put in perspective through the lens of the three main safeguard subjects defined by Dewulf et al. (2015). In addition, an extensive literature review identifies a wide range of possible impact pathways to freshwater resources, establishing the link between different inventory elementary flows (water consumption, emissions, and land use) and their potential to cause long-term freshwater depletion or degradation. Results and discussion: Freshwater as a resource has a particular status in LCA resource assessment. First, it exists in the form of three types of resources: flow, fund, or stock. Then, in addition to being a resource for human economic activities (e.g., hydropower), it is above all a non-substitutable support for life that can be affected by both consumption (source function) and pollution (sink function). Therefore, both types of elementary flows (water consumption and emissions) should be linked to a damage indicator for freshwater as a resource. Land use is also identified as a potential stressor to freshwater resources by altering runoff, infiltration, and erosion processes as well as evapotranspiration. It is suggested to use the concept of recovery period to operationalize this framework: when the recovery period lasts longer than a given period of time, impacts are considered to be irreversible and fall into the concern of freshwater resources protection (i.e., affecting future generations), while short-term impacts effect the AoP ecosystem quality and human health directly. It is shown that it is relevant to include this concept in the impact assessment stage in order to discriminate the long-term from the short-term impacts, as some dynamic fate models already do. Conclusions: This framework provides a solid basis for the consistent development of future LCIA methods for freshwater resources, thereby capturing the potential long-term impacts that could warn decision makers about potential safe water supply issues in the future

    Sub-surface Oxygen and Surface Oxide Formation at Ag(111): A Density-functional Theory Investigation

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    To help provide insight into the remarkable catalytic behavior of the oxygen/silver system for heterogeneous oxidation reactions, purely sub-surface oxygen, and structures involving both on-surface and sub-surface oxygen, as well as oxide-like structures at the Ag(111) surface have been studied for a wide range of coverages and adsorption sites using density-functional theory. Adsorption on the surface in fcc sites is energetically favorable for low coverages, while for higher coverage a thin surface-oxide structure is energetically favorable. This structure has been proposed to correspond to the experimentally observed (4x4) phase. With increasing O concentrations, thicker oxide-like structures resembling compressed Ag2O(111) surfaces are energetically favored. Due to the relatively low thermal stability of these structures, and the very low sticking probability of O2 at Ag(111), their formation and observation may require the use of atomic oxygen (or ozone, O3) and low temperatures. We also investigate diffusion of O into the sub-surface region at low coverage (0.11 ML), and the effect of surface Ag vacancies in the adsorption of atomic oxygen and ozone-like species. The present studies, together with our earlier investigations of on-surface and surface-substitutional adsorption, provide a comprehensive picture of the behavior and chemical nature of the interaction of oxygen and Ag(111), as well as of the initial stages of oxide formation.Comment: 17 pages including 14 figures, Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

    Astrometry and geodesy with radio interferometry: experiments, models, results

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    Summarizes current status of radio interferometry at radio frequencies between Earth-based receivers, for astrometric and geodetic applications. Emphasizes theoretical models of VLBI observables that are required to extract results at the present accuracy levels of 1 cm and 1 nanoradian. Highlights the achievements of VLBI during the past two decades in reference frames, Earth orientation, atmospheric effects on microwave propagation, and relativity.Comment: 83 pages, 19 Postscript figures. To be published in Rev. Mod. Phys., Vol. 70, Oct. 199
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