Locating Photography

The specter of global dissemination haunted photography from its very beginning. This chapter explains two aspects of photography's “globalization”: its use as a “western” technique to document an increasingly colonized world and its dissemination around the world and its adoption by local practitioners. In rural and small‐town central India, the studio retains a central place in most people's encounters with photography. Martín Chambi would retain a lifelong adherence to the purity of the photographic image but other indigenista photographers, such as Juan Manuel Figueroa Aznar, would increasingly use paint alongside photography. A World System Photography, seen in networks that fold locally articulated practices into trajectories that fuse technics, history, and culture, can help people think in new ways about the “location” of photography. Locations have to be re‐imagined as “Terra Infirma”, unstable and complex positions which may have more of the quality of linking sections of a network than of territories

Anesthetic action on the transmission delay between cortex and thalamus explains the beta-buzz observed under propofol anesthesia

In recent years, more and more surgeries under general anesthesia have been performed with the assistance of electroencephalogram (EEG) monitors. An increase in anesthetic concentration leads to characteristic changes in the power spectra of the EEG. Although tracking the anesthetic-induced changes in EEG rhythms can be employed to estimate the depth of anesthesia, their precise underlying mechanisms are still unknown. A prominent feature in the EEG of some patients is the emergence of a strong power peak in the β–frequency band, which moves to the α–frequency band while increasing the anesthetic concentration. This feature is called the beta-buzz. In the present study, we use a thalamo-cortical neural population feedback model to reproduce observed characteristic features in frontal EEG power obtained experimentally during propofol general anesthesia, such as this beta-buzz. First, we find that the spectral power peak in the α– and δ–frequency ranges depend on the decay rate constant of excitatory and inhibitory synapses, but the anesthetic action on synapses does not explain the beta-buzz. Moreover, considering the action of propofol on the transmission delay between cortex and thalamus, the model reveals that the beta-buzz may result from a prolongation of the transmission delay by increasing propofol concentration. A corresponding relationship between transmission delay and anesthetic blood concentration is derived. Finally, an analytical stability study demonstrates that increasing propofol concentration moves the systems resting state towards its stability threshold

Adaptations in antagonist co-activation: Role in the repeated-bout effect

Eccentric exercise results in an adaptation which attenuates muscle damage from subsequent exercise—termed the “repeated-bout effect (RBE).” Purpose: Study examined antagonist co-activation and motor-unit recruitment strategy, assessed via dEMG, concomitant to the RBE. Methods: Nine participants performed 5 sub-maximal isometric trapezoid (ramp-up, hold, ramp-down) contractions at force levels corresponding to 50% and 80% of maximal isometric strength (MVC). Surface EMG signals of the biceps brachii were decomposed into individual motor-unit action potential trains. The relationship between mean firing rate (MFR) of each motor-unit and its recruitment threshold (RT) was examined using linear regression. Eccentric exercise was then performed until biceps brachii MVC had decreased by ~40%. Surface EMG of the biceps and triceps were collected during eccentric exercise. MVC, range-of-motion (ROM), and delayed onset muscle soreness (DOMS) were measured 24-hours, 72-hours, and 1-week following eccentric exercise. Three weeks later all procedures were repeated. Results: Changes in MVC (-32±14% vs -25±10%; p = 0.034), ROM (-11% vs 6%; p = 0.01), and DOMS (31.0±19mm vs 19±12mm; p = 0.015) were attenuated following the second bout of exercise. Triceps EMG was reduced (16.8±9.5% vs. 12.6±7.2%; p = 0.03) during the second bout of eccentric exercise. The slope (-0.60±0.13 vs -0.70±0.18; p = 0.029) and y-intercept (46.5±8.3 vs 53.3±8.8; p = 0.020) of the MFR vs. RT relationship was altered during contractions at 80% of MVC prior to the second bout of eccentric exercise. No changes were observed at 50% of MVC. Conclusion: A reduction in antagonist co-activation during the second bout of eccentric exercise suggests less total force was required to move an identical external load. This finding is supported by the increased negative slope coefficient and an increased y-intercept of the linear relationship between RT and MFR.Funded by University of Oklahoma Graduate College Robberson Grant.Ye

Finite element analysis of construction stability of Thika Dam

High pore water pressures were measured in the fill material of the Thika Dam embankment early in its construction. These caused concern about the subsequent short term stability. Therefore construction was stopped. Stability reassessment and drainage design was performed using finite element analyses before construction was allowed to continue. Different methods of modelling the pore water pressure allowed efficient analysis of various drainage options. The analyses highlighted zones of high shear stress and shear strain, and formation of failure surfaces. They established the necessary level of drainage required to ensure stability, control movement and reduce the risk of residual shear surfaces. Large toe movement was predicted immediately after construction recommences.High pore water pressures were measured in the fill material of the Thika Dam embankment early in its construction. These caused concern about the subsequent short term stability. Therefore construction was stopped. Stability reassessment and drainage design was performed using finite element analyses before construction was allowed to continue. Different methods of modelling the pore water pressure allowed efficient analysis of various drainage options. The analyses highlighted zones of high shear stress and shear strain, and formation of failure surfaces. They established the necessary level of drainage required to ensure stability, control movement and reduce the risk of residual shear surfaces. Large toe movement was predicted immediately after construction recommences

Sampling disturbance effects in the Bothkennar laminated facies

Sample disturbance effects in the laminated facies at the Bothkennar soft clay research site are examined by comparing the results of laboratory tests on specimens obtained from three fixed piston tube samplers. A significant feature of the results is that the sampling process associated with the conventional piston tube used in the UK and Ireland appears to increase the post yield stiffness and the CAUC triaxial undrained strength, reduce the preconsolidation stress, the pore pressure coefficient at failure and induce a strong tendency for dilatant behaviour post peak when compared to tests on specimens from a sampler with a modified (sharper) cutting edge angle. It is reasoned that these findings are caused by material destructuration during the sampling process with the conventional tubes. Increased densification of these specimens caused both by sampling and during anisotropic consolidation may also contribute to these effects. The results are supported by reference to recent analytical work and data for three other soils. It is recommended that the use of these conventional thin walled tubes with a crude cutting edge is abandoned and that some with improved cutting edge geometry replaces them.Other funderEnterprise IrelandBritish Counci