Elastic Wave Scattering from Griffith Cracks

To model elastic wave scattering from fatigue cracks in metals, studies were conducted of wave scattering from artificial cracks using ultrasonic spectroscopy. The cracks are of two dimensional planar strips oriented at various angles and embedded in diffusion bonded titanium alloy. The crack is assumed to behave as a Griffith crack and expressions (derived by Achenbach) to describe diffracted field of elastic waves are used to analyze experimental results

Quantitative assessment of surface roughness using backscattered ultrasound: The effects of finite surface curvature

We have previously described a technique to quantify surface fibrillatory changes in osteoarthritic articular cartilage. In that study, the angular distribution of the scattered acoustic field from an insonifying source directly related to the distribution of surface fibrillatory changes. In the current study, we demonstrate a more sensitive method to quantify surface roughness, the effect of global surface curvature in estimating surface roughness and the utility of using focused transducers in circumventing this potential problem for in vivo work. Phantoms composed of acrylic rods with and without sandpaper grit (about 15 to 72 [mu], mean particle size) applied to the surface were scanned. A more robust angular scattering technique to measure the angle dependent data was employed, in which the integrated squared pressure amplitude over a finite time window (mean power) was measured as a function of incident acoustic angle for varying surface roughnesses and radii of curvature. We show that the potential dynamic range for making roughness discriminations diminishes with decreasing radius of curvature of the acrylic rod phantoms using an unfocused transducer. This effect is minimized with use of a focused transducer. Roughness effects are most evident at sufficiently large angles where incoherent scattering dominates. We conclude that the roughness of cylindrically curved surfaces can be quantitatively assessed using a focused ultrasound beam at sufficiently large incident angles, given that the focal spot size is sufficiently smaller than the radius of curvature of the surface.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31893/1/0000845.pd

Estado, escolas e famílias: públicos escolares e regulação da educação

O texto apresenta alguns resultados de uma investigação recentemente concluída que, genericamente, se inscreve nos complexos processos de (multi)regulação da educação. O estudo desenvolveu-se num concelho do norte de Portugal (convencionalmente designado Vila Formosa), circunscrevendo-se às escolas com oferta de ensino secundário. A análise dos dados sugere que, na topografia complexa dos processos de (multi)regulação do campo escolar, a combinação de medidas de política educativa com recursos e cursos de acção que as diferentes escolas e as diversas categorias de famílias e jovens detêm e adoptam constituem uma tríade de fontes de dinâmicas, umas vezes convergentes, outras vezes em tensão que, por seus efeitos sociológicos cumulativos, geram a reordenação do campo de lutas concorrenciais em torno da educação, lutas essas que parecem penalizar sobretudo as famílias que já sofrem de outras desvantagens.The text presents some results of a recently concluded investigation that, generically, is part of the complex processes of the (multi) regulation of education. The study was developed in a district in the north of Portugal (conventionally designated Vila Formosa) and was limited to schools that offered secondary education. The analysis of the data suggests that, in the complex topography of the processes of (multi)regulation of the school field, the combination of measures of educational policy with resources and courses of action that the different schools and the diverse categories of families and young people possess and adopt constitute a triad of dynamic sources, sometimes convergent and sometimes tense, that, by their cumulative sociological effects, generate the re-ordination of the field of competing struggles in education that seem to penalize, above all, the families that already suffer other disadvantages.El texto presenta algunos resultados de una investigación recientemente finalizada que, genéricamente, se inscribe en los complexos procesos de (multi) regulación de la educación. El estudio se desarrolló en un consejo del norte de Portugal (asignado convencionalmente Vila Formosa), circunscribiéndose a las escuelas con oferta de enseñanza secundaria. El análisis de los datos sugiere que, en la compleja topografía de los procesos de (multi)regulación del campo escolar, la combinación de medidas de política educativa con los recursos y los cursos de acción que las diferentes escuelas y las diversas categorías de familias y jóvenes retienen y que adoptan, constituyen una tríada de fuentes de dinámicas, unas veces convergentes, otras veces en tensión que, por sus efectos sociológicos acumulativos, generan la reordenación del campo de luchas competitivas alrededor de la educación y de los resultados de esas luchas que parecen penalizar principalmente a las familias que ya sufren de otras desventajas.(undefined

Compton Scattering by Nuclei

The concept of Compton scattering by even-even nuclei from giant-resonance to nucleon-resonance energies and the status of experimental and theoretical researches in this field are outlined. Nuclear Compton scattering in the giant-resonance energy-region provides information on the dynamical properties of the in-medium mass of the nucleon. The electromagnetic polarizabilities of the nucleon in the nuclear medium can be extracted from nuclear Compton scattering data obtained in the quasi-deuteron energy-region. Recent results are presented for two-body effects due to the mesonic seagull amplitude and due to the excitation of nucleon internal degrees of freedom accompanied by meson exchanges. Due to these studies the in-medium electromagnetic polarizabilities are by now well understood, whereas the understanding of nuclear Compton scattering in the Delta-resonance range is only at the beginning. Phenomenological methods how to include retardation effects in the scattering amplitude are discussed and compared with model predictions.Comment: 146 pages, 37 figures, submitted to Phys. Report

BINDING PROTEINS AND MEMBRANE TRANSPORT fn1

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72841/1/j.1749-6632.1975.tb31496.x.pd

Quantitative assessment of cartilage surface roughness in osteoarthritis using high frequency ultrasound

Osteoarthritis (OA) is a common disease which affects nearly 50% of people over age 60. Histologic evaluation suggests that fibrillations ~20-150 [mu]m are among the earliest changes in the articular cartilage. We propose a technique to quantify these surface fibrillatory changes in osteoarthritic articular cartilage by considering the angular distribution of the envelope-detected backscattered pressure field from an incident 30-MHz focused transducer. The angular distribution of the scattered acoustic field from an insonifying source will directly relate to the distribution of surface fibrillatory changes. Data are presented for three different grades (400, 500 and 600 grit) of commercially available emory paper and three samples of osteoarthritic femoral head articular cartilage, which were visually assessed as having smooth, intermediate and rough surfaces, respectively. Our preliminary results indicate a probable monotonic relationship between articular cartilage roughening and the degree of broadening in the angle-dependent pressure amplitude. When applied to the emory paper, the technique indicates sensitivity to differences as small as ~5-10 [mu]m in mean roughness. This procedure may provide an extremely sensitive and reproducible means of quantifying and following the cartilage changes observed in early osteoarthritis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30279/1/0000680.pd

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Expert consensus and recommendations on safety criteria for active mobilization of mechanically ventilated critically ill adults

Introduction: The aim of this study was to develop consensus recommendations on safety parameters for mobilizing adult, mechanically ventilated, intensive care unit (ICU) patients. Methods: A systematic literature review was followed by a meeting of 23 multidisciplinary ICU experts to seek consensus regarding the safe mobilization of mechanically ventilated patients. Results: Safety considerations were summarized in four categories: respiratory, cardiovascular, neurological and other. Consensus was achieved on all criteria for safe mobilization, with the exception being levels of vasoactive agents. Intubation via an endotracheal tube was not a contraindication to early mobilization and a fraction of inspired oxygen less than 0.6 with a percutaneous oxygen saturation more than 90% and a respiratory rate less than 30 breaths/minute were considered safe criteria for in- and out-of-bed mobilization if there were no other contraindications. At an international meeting, 94 multidisciplinary ICU clinicians concurred with the proposed recommendations. Conclusion: Consensus recommendations regarding safety criteria for mobilization of adult, mechanically ventilated patients in the ICU have the potential to guide ICU rehabilitation whilst minimizing the risk of adverse events