Sequential Desynchronization in Networks of Spiking Neurons with Partial Reset

The response of a neuron to synaptic input strongly depends on whether or not it has just emitted a spike. We propose a neuron model that after spike emission exhibits a partial response to residual input charges and study its collective network dynamics analytically. We uncover a novel desynchronization mechanism that causes a sequential desynchronization transition: In globally coupled neurons an increase in the strength of the partial response induces a sequence of bifurcations from states with large clusters of synchronously firing neurons, through states with smaller clusters to completely asynchronous spiking. We briefly discuss key consequences of this mechanism for more general networks of biophysical neurons

The Pandemic Leadership Model: A Study of Medical Student Values During COVID-19

Background: Leadership training in medical school continues to grow. Little information exists to guide leadership program development. Concurrently, the COVID-19 pandemic provides a real-world crucible of leadership, allowing insight into qualities and characteristics medical students value. We aim to determine what students value in leadership during a pandemic and the implicit framework students use. Methods: We conducted a cross-sectional, qualitative study using a five-item novel survey instrument developed by a consensus group of experts from family medicine, leadership development, medical education, and survey research to elicit student perceptions of effective and ineffective leadership qualities and examples during the COVID-19 pandemic at the University of Michigan Medical School. We used thematic analysis to identify overarching themes to build a model of leadership integrated with existing theory. Results: 162 students participated across all years of medical school. We identified themes of Communication, Other-Orientation, Personal Characteristics, Decisive Action, and Use of Information. These five themes were then built into the model of Pandemic Leadership within the context of complexity leadership theory and collective leadership theory. This model represents qualities and characteristics students value in good leaders during a crisis. Conclusion: This study is unique in its focus on student perceptions of leadership qualities during a real-world laboratory for leadership. We hope that this information, along with the pandemic leadership model, can serve as the first step toward relevant leadership training programs in medical education. Leadership training programs in medical education would likely benefit from grounding in the student values identified by this study

Reform of High School Mathematics and Science and Opportunity to Learn

This brief concerns the nature of the high school mathematics and science curriculum in the United States. It draws from a large study which documented instructional practices and content using novel methodologies. This research approach is a promising step toward the development of indicators of opportunity to learn. The study also provides encouraging news about the effects of increased standards in math and science - they did not result in a watering down of the curriculum. However, practice in the schools studied is a far cry from the ambitious goals for math and science instruction now being developed by the profession

Predicting green: really radical (plant) predictive processing

In this article we account for the way plants respond to salient features of their environment under the free-energy principle for biological systems. Biological self-organization amounts to the minimization of surprise over time. We posit that any self-organizing system must embody a generative model whose predictions ensure that (expected) free energy is minimized through action. Plants respond in a fast, and yet coordinated manner, to environmental contingencies. They pro-actively sample their local environment to elicit information with an adaptive value. Our main thesis is that plant behaviour takes place by way of a process (active inference) that predicts the environmental sources of sensory stimulation. This principle, we argue, endows plants with a form of perception that underwrites purposeful, anticipatory behaviour. The aim of the article is to assess the prospects of a radical predictive processing story that would follow naturally from the free-energy principle for biological systems; an approach that may ultimately bear upon our understanding of life and cognition more broadly

Nucleon-Nucleon Optical Model for Energies to 3 GeV

Several nucleon-nucleon potentials, Paris, Nijmegen, Argonne, and those derived by quantum inversion, which describe the NN interaction for T-lab below 300$ MeV are extended in their range of application as NN optical models. Extensions are made in r-space using complex separable potentials definable with a wide range of form factor options including those of boundary condition models. We use the latest phase shift analyses SP00 (FA00, WI00) of Arndt et al. from 300 MeV to 3 GeV to determine these extensions. The imaginary parts of the optical model interactions account for loss of flux into direct or resonant production processes. The optical potential approach is of particular value as it permits one to visualize fusion, and subsequent fission, of nucleons when T-lab above 2 GeV. We do so by calculating the scattering wave functions to specify the energy and radial dependences of flux losses and of probability distributions. Furthermore, half-off the energy shell t-matrices are presented as they are readily deduced with this approach. Such t-matrices are required for studies of few- and many-body nuclear reactions.Comment: Latex, 40 postscript pages including 17 figure