Coordinated neuronal ensembles in primary auditory cortical columns.

The synchronous activity of groups of neurons is increasingly thought to be important in cortical information processing and transmission. However, most studies of processing in the primary auditory cortex (AI) have viewed neurons as independent filters; little is known about how coordinated AI neuronal activity is expressed throughout cortical columns and how it might enhance the processing of auditory information. To address this, we recorded from populations of neurons in AI cortical columns of anesthetized rats and, using dimensionality reduction techniques, identified multiple coordinated neuronal ensembles (cNEs), which are groups of neurons with reliable synchronous activity. We show that cNEs reflect local network configurations with enhanced information encoding properties that cannot be accounted for by stimulus-driven synchronization alone. Furthermore, similar cNEs were identified in both spontaneous and evoked activity, indicating that columnar cNEs are stable functional constructs that may represent principal units of information processing in AI

Soil nitrogen affects phosphorus recycling: foliar resorption and plant–soil feedbacks in a northern hardwood forest

Previous studies have attempted to link foliar resorption of nitrogen and phosphorus to their respective availabilities in soil, with mixed results. Based on resource optimization theory, we hypothesized that the foliar resorption of one element could be driven by the availability of another element. We tested various measures of soil N and P as predictors of N and P resorption in six tree species in 18 plots across six stands at the Bartlett Experimental Forest, New Hampshire, USA. Phosphorus resorption efficiency (P , 0.01) and proficiency (P ¼ 0.01) increased with soil N content to 30 cm depth, suggesting that trees conserve P based on the availability of soil N. Phosphorus resorption also increased with soil P content, which is difficult to explain based on single-element limitation, but follows from the correlation between soil N and soil P. The expected single-element relationships were evident only in the O horizon: P resorption was high where resin-available P was low in the Oe (P , 0.01 for efficiency, P , 0.001 for proficiency) and N resorption was high where potential N mineralization in the Oa was low (P , 0.01 for efficiency and 0.11 for proficiency). Since leaf litter is a principal source of N and P to the O horizon, low nutrient availability there could be a result rather than a cause of high resorption. The striking effect of soil N content on foliar P resorption is the first evidence of multiple-element control on nutrient resorption to be reported from an unmanipulated ecosystem

Drivers of root and fungal litter decomposition: implications for soil carbon cycling

University of Minnesota Ph.D. dissertation. May 2021. Major: Ecology, Evolution and Behavior. Advisors: Sarah Hobbie, Peter Kennedy. 1 computer file (PDF); v, 131 pages.Globally, soils contain more carbon (C) than vegetation and the atmosphere combined. Despite clear importance to the global C budget, estimates of C fluxes into and out of soils remain highly uncertain. Decomposition is the dominant process by which C is lost from soil, but most of what is known about the controls of this process comes from studies of leaf litter at the soil surface. My first two chapters explore factors affecting the decomposition of two common belowground litter types. Chapter one is a global meta-analysis of the drivers of fine root decomposition, and is the first to explore the effects of species-level traits in addition to climate and substrate chemistry. My second chapter describes an experiment characterizing the dynamics and chemical drivers of fungal necromass decomposition, an important and understudied flux of soil C. My final chapter focuses on the role of soil fungi in the formation of “stabilized” soil C in the form of mineral associated organic matter (MAOM). Here, I call into question the current assumption that new MAOM formation in soil occurs in close proximity to root surfaces. Using quantitative estimates of fungal exploration, I put forth the hypothesis that fungal hyphae play an underappreciated role in distributing C through soil, and that hyphal contact with minerals encourages the formation of MAOM. This work suggests that current potential for MAOM formation in soils is significantly underestimated by not accounting for the impact of fungi.See, Craig. (2021). Drivers of root and fungal litter decomposition: implications for soil carbon cycling. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/223124

Numerical loop quantum cosmology: an overview

A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key prediction of the bounce at the Planck scale in different models, and the numerical methods used to analyze the properties of the quantum difference operator and the von Neumann stability issues. Using the quantization of a massless scalar field in an isotropic spacetime as a template, an attempt is made to highlight the complementarity of different methods to gain understanding of the new physics emerging from the quantum theory. Open directions which need to be explored with more refined numerical methods are discussed.Comment: 33 Pages, 4 figures. Invited contribution to appear in Classical and Quantum Gravity special issue on Non-Astrophysical Numerical Relativit

Hacia un Modelo Teórico de Liderazgo Compartido e Innovación en la Empresa Familiar

We advocate shared leadership as a key mechanism for unlocking innovation in family businesses.  Family businesses, however, typically emphasize hierarchical leadership, reflecting the family power structure, which can pose challenges for successful innovation by limiting resources and knowledge sharing between family and non-family members. Shared leadership, enabled by both empowerment from formal hierarchical leaders, as well as self-leadership practices across the organization, can help to overcome this challenge by leveraging the familiness, and related social capital, present in family businesses. Exploring the impact of shared leadership on innovation, familiness and social capital are proposed to improve innovation in the family business. Shared leadership is proffered as a potentially powerful tool for tapping the potential of familiness, enhancing bridging ties, and building bonding ties, contributing to resources and knowledge sharing between familial and non-familial members. Theoretical implications, future research directions and implications for managerial practice are presented.Aunque las empresas familiares tienen a un liderazgo jerárquico, reflejo de la estructura de poder familiar, defendemos el liderazgo compartido como un mecanismo clave para fomentar la innovación en estas empresas, ya que el modelo jerárquico puede dificultar el éxito de los procesos de innovación al limitar el intercambio de recursos y conocimientos entre miembros familiares y no familiares. El liderazgo compartido surge tanto del empoderamiento de los líderes jerárquicos formales como de las prácticas de auto-liderazgo en la organización. Nuestro estudio propone que la familiaridad (familiness) y el capital social, elementos característicos de las empresas familiares, pueden desempeñar un papel fundamental en la mejora de la capacidad innovadora de estas organizaciones. El liderazgo compartido se presenta como una herramienta potencialmente poderosa para aprovechar el valor de la familiaridad, fortalecer los lazos de unión y de conexión, promoviendo así el intercambio de recursos y conocimientos entre miembros familiares y no familiares. Finalmente, se discuten las implicaciones teóricas, futuras líneas de investigación y consideraciones para la práctica directiva

Information diversity in individual auditory cortical neurons is associated with functionally distinct coordinated neuronal ensembles

Neuronal activity in auditory cortex is often highly synchronous between neighboring neurons. Such coordinated activity is thought to be crucial for information processing. We determined the functional properties of coordinated neuronal ensembles (cNEs) within primary auditory cortical (AI) columns relative to the contributing neurons. Nearly half of AI cNEs showed robust spectro-temporal receptive fields whereas the remaining cNEs showed little or no acoustic feature selectivity. cNEs can therefore capture either specific, time-locked information of spectro-temporal stimulus features or reflect stimulus-unspecific, less-time specific processing aspects. By contrast, we show that individual neurons can represent both of those aspects through membership in multiple cNEs with either high or absent feature selectivity. These associations produce functionally heterogeneous spikes identifiable by instantaneous association with different cNEs. This demonstrates that single neuron spike trains can sequentially convey multiple aspects that contribute to cortical processing, including stimulus-specific and unspecific information