In situ characterization of structural dynamics in swelling hydrogels

Characterizing the structural morphology and the local viscoelastic properties of soft complex systems raises significant challenges. Here we introduce a dynamic light scattering method capable of in situ, continuous monitoring of structural changes in evolving systems such as swelling gels. We show that the inherently non-stationary dynamics of embedded probes can be followed using partially coherent radiation, which effectively isolates only single scattering contributions even during the dramatic changes in the scattering regime. Using a simple and robust experimental setup, we demonstrate the ability to continuously monitor the structural dynamics of chitosan hydrogels formed by the Ag+ ion-triggered gelation during their long-term swelling process. We demonstrate that both the local viscoelastic properties of the suspending medium and an effective cage size experienced by diffusing probe particles loaded into the hydrogel can be recovered and used to describe the structural dynamics of hydrogels with different levels of cross-linking. This characterization capability is critical for defining and controlling the hydrogel performance in different biomedical applications

Bridging different perspectives for biocultural conservation: art-based participatory research on native maize conservation in two indigenous farming communities in Oaxaca, Mexico

Native maize conservation rests on the custody of traditional and indigenous small-scale farmers, but their traditional practices and way of life are challenged by multiple forces associated with globalization, international trade and neoliberal agricultural policies. Through participatory art-based research with two indigenous communities in Oaxaca, Mexico, we identified the main challenges and strategies for native maize conservation, as perceived by these farming communities. We implemented a stepwise method to elicit local strategies for biocultural conservation pertinent across gender and generations. We conclude that understanding the heterogeneity of perspectives is important for identifying root causes of agrobiodiversity decline and strategies for biocultural native maize conservation

The human motor cortex microcircuit: insights for neurodegenerative disease

The human motor cortex comprises a microcircuit of five interconnected layers with different cell types. In this Review, we use a layer-specific and cell-specific approach to integrate physiological accounts of this motor cortex microcircuit with the pathophysiology of neurodegenerative diseases affecting motor functions. In doing so we can begin to link motor microcircuit pathology to specific disease stages and clinical phenotypes. Based on microcircuit physiology, we can make future predictions of axonal loss and microcircuit dysfunction. With recent advances in high-resolution neuroimaging we can then test these predictions in humans in vivo, providing mechanistic insights into neurodegenerative disease