Late-stage tectonic evolution of the Al-Hajar Mountains, Oman: New constraints from Palaeogene sedimentary units and low-temperature thermochronometry

Mountain building in the Al-Hajar Mountains (NE Oman) occurred during two major shortening stages, related to the convergence between Africa-Arabia and Eurasia, separated by nearly 30 Ma of tectonic quiescence. Most of the shortening was accommodated during the Late Cretaceous, when northward subduction of the Neo-Tethys Ocean was followed by the ophiolites obduction on top of the former Mesozoic margin. This shortening event lasted until the latest Santonian - early Campanian. Maastrichtian to Eocene carbonates unconformably overlie the eroded nappes and seal the Cretaceous foredeep. These neo-autochthonous post-nappe sedimentary rocks were deformed, along with the underlying Cretaceous tectonic pile, during the second shortening event, itself including two main exhumation stages. In this study we combine remotely sensed structural data, seismic interpretation, field-based structural investigations and apatite (U-Th)/He (AHe) cooling ages to obtain new insights into the Cenozoic deformation stage. Seismic interpretation indicates the occurrence of a late Eocene flexural basin, later deformed by an Oligocene thrusting event, during which the post-nappe succession and the underlying Cretaceous nappes of the internal foredeep were uplifted. This stage was followed by folding of the post-nappe succession during the Miocene. AHe data from detrital siliciclastic deposits in the frontal area of the mountain chain provide cooling ages spanning from 17.3 to 42 Ma, consistent with available data for the structural culminations of Oman. Our work points out how renewal of flexural subsidence in the foredeep and uplift of the mountain belt were coeval processes, followed by layer-parallel shortening preceding final fold amplification

Acute Effects of Assisted Cycling Therapy on Post-Stroke Motor Function: A Pilot Study

Background. Stroke is the most common cause of long-term disability in the United States (US). Assisted Cycling Therapy (ACT) at cadences of about 80 rpm has been associated with improvements in motor and clinical function in other clinical populations. The acute effects of ACT on motor function of persons with stroke have not been investigated. Objectives. The primary purpose of this cross-over trial was to compare the effects of ACT, voluntary cycling (VC), and no cycling (NC) on upper (Box and Blocks Test) and lower extremity motor function (Lower Extremity Motor Coordination Test) in adults with chronic stroke (age: 60 +/- 16 years; months since stroke: 96 +/- 85). The secondary purpose was to examine average cycling cadence and ratings of perceived exertion as predictors of change in motor function following the exercise session. Methods. Twenty-two participants (female = 6, male = 16) completed one 20-min session each of ACT (mean cadence = 79.5 rpm, VC (mean cadence = 51.5 rpm), and NC on separate days in quasi-counterbalanced fashion). Results. Main effects of intervention did not differ between ACT and VC. Within-intervention analyses revealed significant (p < 0.05) pre- to posttest changes in all outcome measures for ACT but only in the Lower Extremity Motor Coordination Test on the non-paretic side for VC. Trend analyses revealed a positive relationship between average ACT cadences and improvements in upper and lower extremity motor function (p < 0.05). A positive relationship between average VC cadences and lower extremity function was also revealed (p < 0.05). Conclusion. ACT and VC produced similar acute improvements in paretic and non-paretic lower extremity motor function whereas changes in upper extremity motor function were more limited. Faster cycling cadences seem to be associated with greater acute effects.Athletics Research Grant Program of the Graduate and Professional Student Organization at Arizona State University [asu 0010E 16736]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Acute Effects of Assisted Cycling Therapy on Post-Stroke Motor Function: A Pilot Study

Background. Stroke is the most common cause of long-term disability in the United States (US). Assisted Cycling Therapy (ACT) at cadences of about 80 rpm has been associated with improvements in motor and clinical function in other clinical populations. The acute effects of ACT on motor function of persons with stroke have not been investigated. Objectives. The primary purpose of this cross-over trial was to compare the effects of ACT, voluntary cycling (VC), and no cycling (NC) on upper (Box and Blocks Test) and lower extremity motor function (Lower Extremity Motor Coordination Test) in adults with chronic stroke (age: 60 +/- 16 years; months since stroke: 96 +/- 85). The secondary purpose was to examine average cycling cadence and ratings of perceived exertion as predictors of change in motor function following the exercise session. Methods. Twenty-two participants (female = 6, male = 16) completed one 20-min session each of ACT (mean cadence = 79.5 rpm, VC (mean cadence = 51.5 rpm), and NC on separate days in quasi-counterbalanced fashion). Results. Main effects of intervention did not differ between ACT and VC. Within-intervention analyses revealed significant (p < 0.05) pre- to posttest changes in all outcome measures for ACT but only in the Lower Extremity Motor Coordination Test on the non-paretic side for VC. Trend analyses revealed a positive relationship between average ACT cadences and improvements in upper and lower extremity motor function (p < 0.05). A positive relationship between average VC cadences and lower extremity function was also revealed (p < 0.05). Conclusion. ACT and VC produced similar acute improvements in paretic and non-paretic lower extremity motor function whereas changes in upper extremity motor function were more limited. Faster cycling cadences seem to be associated with greater acute effects.Athletics Research Grant Program of the Graduate and Professional Student Organization at Arizona State University [asu 0010E 16736]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Reconstruction of four-dimensional rockfall trajectories using remote sensing and rock-based accelerometers and gyroscopes

This work focuses on the in-depth reconstruction of the full set of parameters of interest in single-block rockfall trajectories. A comprehensive understanding of rockfall trajectories holds the promise to enhance the application of numerical models for engineering hazard analysis. Such knowledge is equally important to investigate wider cascade problems in steep terrain. Here, we present a full four-dimensional trajectory reconstruction of the “Chant Sura” rockfall experiment performed with EOTA221 norm rocks. The data analysis allows a complete kinematic description of a rock's trajectory in real terrain and underscores the physical complexity of rock–ground interactions. In situ accelerometer and gyroscope data are combined with videogrammetric and unmanned aerial-systems mapping techniques to understand the role of rock rotations, ground penetration and translational scarring in rockfall motion. The exhaustive trajectory reconstruction provides information over the complete flight path such as translational velocity vectors, angular velocities, impact duration and forces, ballistic jump heights, and lengths. The experimental data provide insight into the basic physical processes detailing how rotating rocks of general shape penetrate, rebound and scar ground terrain. In future, the data will serve as a calibration basis to enhance numerical rockfall modelling.</p

Tercera Conferencia de Creative Commons en América Latina

Esta obra y todos y sus contenidos se encuentran licenciados bajos la licencia Creative Commons Atribución 3.0 unported.La presente compilación reúne las historias y el estado actual de los capítulos de Creative Commons en América Latina. Organizada por Bienes Comunes A.C., la Tercera Conferencia de Creative Commons en América Latina (Buenos Aires 2010) significó una excelente oportunindad para invitar a los líderes de los capítulos locales y a sus respectivas instituciones a escribir colaborativamente nuestra historia regional común. La generosa respuesta de cada uno de ellos y el financiamiento recibido de cada uno de ellos (Catalyst Grant) permitió alcanzar esta obra. La compilación consta de diez capítulos que, ordenados alfabéticamente, describen las historias de cada capítulo, sus formas de trabajo, relaciones con las comunidades, proyectos y próximos pasos. Se incluyen las experiencias de Argentina, Brasil, Chile, Colombia, Costa Rica, Ecuador, Guatemala, México, Perú y Perto Rico.Bienes Comunes A.C., Fundación Sociedades Digitales, Creative Commons, Universidad de Costa Rica, otras...UCR::Vicerrectoría de Investigació

The significance of the F variant of alpha-1-antitrypsin and unique case report of a PiFF homozygote

BackgroundInheritance of the F variant of alpha-1-antitrypsin is associated with normal circulating protein levels, but it is believed to be dysfunctional in its ability to inhibit neutrophil elastase and therefore has been implicated as a susceptibility factor for the development of emphysema. In this study, its functional characteristics were determined following the identification of a unique patient with the PiFF phenotype, and the implications as a susceptibility factor for emphysema are considered both in homozygotes and heterozygotes.MethodsSecond order association rate constants were measured for M, Z, S and F variants of alpha-1-antitrypsin with neutrophil elastase and proteinase 3. Clinical characteristics of the PiFF homozygote and six PiFZ heterozygote subjects were studied.ResultsThe F variant had a reduced association rate constant with neutrophil elastase (5.60???0.83 ? 106 M-1?s-1) compared to the normal M variant (1.45???0.02 ? 107 M-1?s-1), indicating an increased time to inhibition that was comparable to that of the Z variant (7.34???0.03 ? 106 M-1?s-1). The association rate constant for the F variant and proteinase 3 (1.06???0.22 ? 106 M-1?s-1) was reduced compared to that with neutrophil elastase, but was similar to that of other alpha-1-antitrypsin variants. Of the six PiFZ heterozygotes, five had airflow obstruction and radiological evidence of emphysema. The PiFF homozygote had airflow obstruction but no emphysema. None of the patients had clinical evidence of liver disease.ConclusionsThe F variant may increase susceptibility to elastase-induced lung damage but not emphysema, whereas co-inheritance with the Z deficiency allele may predispose to emphysema despite reasonable plasma concentrations of alpha-1-antitrypsin

Late-stage tectonic evolution of the Al-Hajar Mountains, Oman: New constraints from Palaeogene sedimentary units and low-temperature thermochronometry

Mountain building in the Al-Hajar Mountains (NE Oman) occurred during two major shortening stages, related to the convergence between Africa-Arabia and Eurasia, separated by nearly 30 Ma of tectonic quiescence. Most of the shortening was accommodated during the Late Cretaceous, when northward subduction of the Neo-Tethys Ocean was followed by the ophiolites obduction on top of the former Mesozoic margin. This shortening event lasted until the latest Santonian - early Campanian. Maastrichtian to Eocene carbonates unconformably overlie the eroded nappes and seal the Cretaceous foredeep. These neo-autochthonous post-nappe sedimentary rocks were deformed, along with the underlying Cretaceous tectonic pile, during the second shortening event, itself including two main exhumation stages. In this study we combine remotely sensed structural data, seismic interpretation, field-based structural investigations and apatite (U-Th)/He (AHe) cooling ages to obtain new insights into the Cenozoic deformation stage. Seismic interpretation indicates the occurrence of a late Eocene flexural basin, later deformed by an Oligocene thrusting event, during which the post-nappe succession and the underlying Cretaceous nappes of the internal foredeep were uplifted. This stage was followed by folding of the post-nappe succession during the Miocene. AHe data from detrital siliciclastic deposits in the frontal area of the mountain chain provide cooling ages spanning from 17.3 to 42 Ma, consistent with available data for the structural culminations of Oman. Our work points out how renewal of flexural subsidence in the foredeep and uplift of the mountain belt were coeval processes, followed by layer-parallel shortening preceding final fold amplification