Interactive Dynamics of Cell Volume and Cell Death in Human Erythrocytes Exposed to α-Hemolysin from Escherichia coli

α-hemolysin (HlyA) of E. coli binds irreversibly to human erythrocytes and induces cell swelling, ultimately leading to hemolysis. We characterized the mechanism involved in water transport induced by HlyA and analyzed how swelling and hemolysis might be coupled. Osmotic water permeability (Pf) was assessed by stopped-flow light scattering. Preincubation with HlyA strongly reduced Pf in control- and aquaporin 1-null red blood cells, although the relative Pf decrease was similar in both cell types. The dynamics of cell volume and hemolysis on RBCs was assessed by electrical impedance, light dispersion and hemoglobin release. Results show that HlyA induced erythrocyte swelling, which is enhanced by purinergic signaling, and is coupled to osmotic hemolysis. We propose a mathematical model of HlyA activity where the kinetics of cell volume and hemolysis in human erythrocytes depend on the flux of osmolytes across the membrane, and on the maximum volume that these cells can tolerate. Our results provide new insights for understanding signaling and cytotoxicity mediated by HlyA in erythrocytes.

Nascent academic entrepreneurs and identity work at the boundaries of professional domains

Higher education institutions promote academic entrepreneurship through organizational arrangements such as innovation programs, incubators, and accelerators aimed at implementing the third mission of the university. While research has examined how these multi-professional arrangements support entrepreneurial efforts, less is known about their individual level implications which emerge as researchers are exposed to different professional values and practices. This article draws on a longitudinal qualitative study on an innovation program to investigate through what kinds of identity processes nascent academic entrepreneurs construct their professional identities and how as part of these processes they position themselves in relation to different professional domains. The analysis demonstrates three identity construction processes (hybridization, rejecting hybridization, and transitioning) and their associated identity work tactics (compartmentalizing, protecting, and reframing) at the boundaries of professional domains. Our contribution is in demonstrating how nascent academic entrepreneurs’ identity construction processes are influenced by internally and externally oriented identity work and their interactive dynamics. Moreover, the findings advance our understanding of how individuals can purposefully mould the fluidity of domain boundaries through identity work by making boundaries bridgeable, impermeable, or permeable. These findings have value for those developing organizational arrangements for the promotion of academic entrepreneurship and entrepreneurial identities.

Dynamics of Mosquito Population Models with Spatial Diffusion

In this paper, we study some reaction-diffusion models of interactive dynamics of the wild and sterile mosquitoes. The well-posedness of the concerned model is proved. The stability of the steady states is discussed. Numerical simulations are presented to illustrate our theoretical results.

Contact and Physical Interaction

This article reviews approaches to controlling robots undergoing physical contact and dynamic interaction with objects in the world. Conventional motion control is compared with a hybrid combination of position and force control. Several challenges are reviewed, most importantly the problems of instability: dynamic instability due to coupling, and static instability due to exerting force. Energetically passive interactive dynamics addresses the former; a minimum stiffness proportional to the force exerted addresses the latter. Actuators, which dominate the robot's interactive dynamics, are briefly surveyed, including series elastic, variable-stiffness, and emerging designs. A comparison with human performance is made. A bioinspired approach to controlling interactive dynamics (mechanical impedance or admittance) is reviewed. Robot configuration profoundly modulates apparent inertia, whereas force feedback control has minimal influence. Superimposing first-order mechanical impedances simplifies controlling many degrees of freedom. It manages redundancy while preserving passivity (unlike null-space projection methods) and enables seamless operation into and out of singular configurations. Expected final online publication date for the Annual Review of Control, Robotics, and Autonomous Systems, Volume 5 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

RESEARCH OF THE MACROINSTITUTIONAL CONTEXTS OF THE STRUCTURE AND DYNAMICS OF INTERACTION OF TECHNOLOGICAL INNOVATION SYSTEMS

Цель статьи - дать оценку вопросам взаимодействия между технологическими инновационными системами и некоторыми контекстными структурами. В частности, автором выделены и рассматриваются четыре особенно важных типа макроинституциональных контекстных структур: технологических, отраслевых, экстраторных и регуляторных. Для каждого из них автор приводит примеры различных способов взаимодействия контекстных структур с центральными технологическими системами и того, как наше понимание динамики технологической инновационной системы улучшается при применении данной методологии. Научная новизна статьи заключается в предложенном автором новом подходе описания контекстных структур через механизм интерактивной динамики, который демонстрирует некоторую степень институциональной согласованности. Также приводятся критерии, позволяющие различать два интерактивных вида взаимодействия, которые в свою очередь характеризуются различной степенью взаимозависимости между центральной технологической инновационной системой и конкретными контекстными структурами. This article discusses the interaction between technological innovation systems and some contextual structures. In particular, we identify and consider four particularly important types of macro-institutional contextual structures: technological, sectoral, extratorial, and regulatory. For each of them, we provide examples of different ways in which contextual structures interact with central technological systems and how our understanding of the dynamics of a technological innovation system improves when applying this methodology. In addition, the article offers a new approach to describing contextual structures through the mechanism of interactive dynamics, which demonstrate a certain degree of institutional coherence. Criteria are also provided to distinguish between two interactive types of interaction, which in turn are characterized by a different degree of interdependence between the central technological innovation system and specific contextual structures.