Outer-totalistic cellular automata on graphs

We present an intuitive formalism for implementing cellular automata on arbitrary topologies. By that means, we identify a symmetry operation in the class of elementary cellular automata. Moreover, we determine the subset of topologically sensitive elementary cellular automata and find that the overall number of complex patterns decreases under increasing neighborhood size in regular graphs. As exemplary applications, we apply the formalism to complex networks and compare the potential of scale-free graphs and metabolic networks to generate complex dynamics.Comment: 5 pages, 4 figures, 1 table. To appear in Physics Letters

Post-Obergefell v. Hodges: How LGBT Contact Can Alter Public LGBT Policy Positions in the U.S. and Arkansas

The Contact Theory (CT) of attitudinal change has utilized to understand perceptions of minority-group members and the policies that surround them since the 1950s. It has further been used to specifically examine how we form our opinions of LGBT-identifying individuals, the LGBT community, and LGBT policies more generally. However, further evidence is still needed from the CT literature surrounding how this form of contact interacts with individuals’ social identities to determine and alter their LGBT policy positions, how the level of contact with LGBT persons might have differing effects on these positions, and whether LGBT contact holds the same effects across multiple LGBT policy issues. Additionally, the literature surrounding LGBT contact and policy position formation has largely been limited to studies at the U.S. national level, which necessitates the examination of state-specific contexts to understand whether the relationships between LGBT contact and LGBT policy positions are stable across geographical location. As such, the following three studies address 1) whether and in what ways contact with LGBT individuals can influence Americans’ views of major LGBT policies, 2) whether this interaction can be found within a state with a more tumultuous history with LGBT rights, and 3) what, if any, role the moral dimensions of each LGBT policy impact contact’s effect on policy position formation

Reply to ''Comment on 'Regularizing Capacity of Metabolic Networks' ''

In a recent paper [C. Marr, M. Mueller-Linow, and M.-T. Huett, Phys. Rev. E 75, 041917 (2007)] we discuss the pronounced potential of real metabolic network topologies, compared to randomized counterparts, to regularize complex binary dynamics. In their comment [P. Holme and M. Huss, arXiv:0705.4084v1], Holme and Huss criticize our approach and repeat our study with more realistic dynamics, where stylized reaction kinetics are implemented on sets of pairwise reactions. The authors find no dynamic difference between the reaction sets recreated from the metabolic networks and randomized counterparts. We reproduce the author's observation and find that their algorithm leads to a dynamical fragmentation and thus eliminates the topological information contained in the graphs. Hence, their approach cannot rule out a connection between the topology of metabolic networks and the ubiquity of steady states.Comment: 2 pages, 2 figure

Perspective: network-guided pattern formation of neural dynamics

The understanding of neural activity patterns is fundamentally linked to an understanding of how the brain's network architecture shapes dynamical processes. Established approaches rely mostly on deviations of a given network from certain classes of random graphs. Hypotheses about the supposed role of prominent topological features (for instance, the roles of modularity, network motifs, or hierarchical network organization) are derived from these deviations. An alternative strategy could be to study deviations of network architectures from regular graphs (rings, lattices) and consider the implications of such deviations for self-organized dynamic patterns on the network. Following this strategy, we draw on the theory of spatiotemporal pattern formation and propose a novel perspective for analyzing dynamics on networks, by evaluating how the self-organized dynamics are confined by network architecture to a small set of permissible collective states. In particular, we discuss the role of prominent topological features of brain connectivity, such as hubs, modules and hierarchy, in shaping activity patterns. We illustrate the notion of network-guided pattern formation with numerical simulations and outline how it can facilitate the understanding of neural dynamics

In search of the millennial : is there a distinctive millennial identity and what might this mean for our understanding of identity in organisations? : a study of emerging identities in Mexican young adults

Ideas of selfhood in contemporary society are increasingly understood in terms of generational membership (Rudolph, Rauvola & Zacher, 2018; Howe & Strauss, 2000). Popular discourses of generational identity offer individuals alternatives for self- definition in ways akin to traditional social identities (Gilleard, 2004). The Millennial Generation (born 1981 to 2000) is portrayed as particularly transformative, differentiated from its predecessors through a series of millennial roles and a distinctive portrayal of leadership (Howe & Strauss, 2000; Elmore, 2009).Contemporary organisations are also conceptualised as spaces for self-definition (Brown, 2015). Individuals are theorised as “identity workers” (Alvesson & Willmott, 2002, p. 622, italics in original) who craft an organisational self subject to identity regulation and control (Reedy, King & Coupland, 2016). Leader identity has received particular attention from scholars (Sinclair, 2011) and is especially relevant to the popular discourse of The Millennial Generation.This qualitative research finds only weak support for claims of a distinctive millennial identity. Further, the participants’ narratives suggest only partial support for a distinctive millennial understanding of leadership. These findings suggest discourses of generational identity overestimate the power of change, and underestimate that of continuity and stability, in self-definition. Data was collected through open-ended interviews with twenty-four young adult Mexicans.This research theorises the lack of millennial distinctiveness in the participants’ accounts as attributable to the popular discourse’s over-reliance on a ‘digital native’ portrayal (Prensky, 2001), one not supported by academic research. Secondly, it conceptualises the participants’ emerging leader identity in terms of micro and macro processes of identity construction and not solely in terms of dominant leader discourses. It recognises the participants undertaking identity work to adapt and mould dominant discourses into more nuanced leader portrayals. Thirdly, it theorises an alternative portrayal of emerging identity in young adulthood characterised by information search (Berzonsky, 1989) and the continual refinement of ideas of selfhood

Design and Development of Miniature Mechanisms for Small Spacecraft

With the continued push for smaller, faster, and cheaper spacecraft comes a new era in mechanism design. The desire to develop “Micro Satellites”, along with advances in the processing and selection of materials, have created an abundance of opportunities to miniaturize mechanisms. Simple designs with direct applications of developing technologies are ideal for these miniature mechanisms. This paper will focus on the design and development of a miniature satellite “tool kit”. Six mechanisms were developed by Starsys Research and the Applied Physics Laboratory (APL) at John Hopkins University (JHU) under a NASA Advanced Technology Development (ATD) Program. The mechanisms developed included a Micro and Mini Separation Nut, a Mini Rotary Actuator, a Micro Burn Wire Release, a SMA Linear Actuator, and a SMA Redundant Release Mechanism. The paper will discuss the concepts evaluated, designs chosen for fabrications, problems encountered during development, achieved performance characteristics, and recommendations for future development

Two distinct logical types of network control in gene expression profiles

In unicellular organisms such as bacteria the same acquired mutations beneficial in one environment can be restrictive in another. However, evolving Escherichia coli populations demonstrate remarkable flexibility in adaptation. The mechanisms sustaining genetic flexibility remain unclear. In E. coli the transcriptional regulation of gene expression involves both dedicated regulators binding specific DNA sites with high affinity and also global regulators - abundant DNA architectural proteins of the bacterial chromoid binding multiple low affinity sites and thus modulating the superhelical density of DNA. The first form of transcriptional regulation is dominantly pairwise and specific, representing digitial control, while the second form is (in strength and distribution) continuous, representing analog control. Here we look at the properties of effective networks derived from significant gene expression changes under variation of the two forms of control and find that upon limitations of one type of control (caused e.g. by mutation of a global DNA architectural factor) the other type can compensate for compromised regulation. Mutations of global regulators significantly enhance the digital control; in the presence of global DNA architectural proteins regulation is mostly of the analog type, coupling spatially neighboring genomic loci; together our data suggest that two logically distinct types of control are balancing each other. By revealing two distinct logical types of control, our approach provides basic insights into both the organizational principles of transcriptional regulation and the mechanisms buffering genetic flexibility. We anticipate that the general concept of distinguishing logical types of control will apply to many complex biological networks.Comment: 19 pages, 6 figure