Characteristics of pattern formation and evolution in approximations of physarum transport networks

Most studies of pattern formation place particular emphasis on its role in the development of complex multicellular body plans. In simpler organisms, however, pattern formation is intrinsic to growth and behavior. Inspired by one such organism, the true slime mold Physarum polycephalum, we present examples of complex emergent pattern formation and evolution formed by a population of simple particle-like agents. Using simple local behaviors based on Chemotaxis, the mobile agent population spontaneously forms complex and dynamic transport networks. By adjusting simple model parameters, maps of characteristic patterning are obtained. Certain areas of the parameter mapping yield particularly complex long term behaviors, including the circular contraction of network lacunae and bifurcation of network paths to maintain network connectivity. We demonstrate the formation of irregular spots and labyrinthine and reticulated patterns by chemoattraction. Other Turing-like patterning schemes were obtained by using chemorepulsion behaviors, including the self-organization of regular periodic arrays of spots, and striped patterns. We show that complex pattern types can be produced without resorting to the hierarchical coupling of reaction-diffusion mechanisms. We also present network behaviors arising from simple pre-patterning cues, giving simple examples of how the emergent pattern formation processes evolve into networks with functional and quasi-physical properties including tensionlike effects, network minimization behavior, and repair to network damage. The results are interpreted in relation to classical theories of biological pattern formation in natural systems, and we suggest mechanisms by which emergent pattern formation processes may be used as a method for spatially represented unconventional computation. © 2010 Massachusetts Institute of Technology

Finite size scaling of the correlation length above the upper critical dimension

We show numerically that correlation length at the critical point in the five-dimensional Ising model varies with system size L as L^{5/4}, rather than proportional to L as in standard finite size scaling (FSS) theory. Our results confirm a hypothesis that FSS expressions in dimension d greater than the upper critical dimension of 4 should have L replaced by L^{d/4} for cubic samples with periodic boundary conditions. We also investigate numerically the logarithmic corrections to FSS in d = 4.Comment: 5 pages, 6 postscript figure

On electrical correlates of Physarum polycephalum spatial activity: Can we see Physarum Machine in the dark?

Plasmodium of Physarum polycephalum is a single cell visible by unaided eye, which spans sources of nutrients with its protoplasmic network. In a very simple experimental setup we recorded electric potential of the propagating plasmodium. We discovered a complex interplay of short range oscillatory behaviour combined with long range, low frequency oscillations which serve to communicate information between different parts of the plasmodium. The plasmodium's response to changing environmental conditions forms basis patterns of electric activity, which are unique indicators of the following events: plasmodium occupies a site, plasmodium functions normally, plasmodium becomes `agitated' due to drying substrate, plasmodium departs a site, and plasmodium forms sclerotium. Using a collective particle approximation of Physarum polycephalum we found matching correlates of electrical potential in computational simulations by measuring local population flux at the node positions, generating trains of high and low frequency oscillatory behaviour. Motifs present in these measurements matched the response `grammar' of the plasmodium when encountering new nodes, simulated consumption of nutrients, exposure to simulated hazardous illumination and sclerotium formation. The distributed computation of the particle collective was able to calculate beneficial network structures and sclerotium position by shifting the active growth zone of the simulated plasmodium. The results show future promise for the non-invasive study of the complex dynamical behaviour within --- and health status of --- living systems

The Adoption of RFID Technology in the Retail Supply Chain

This article examines current developments regarding the adoption of RFID technology in the retail supply chain. An explanation is provided of what Radio Frequency Technology (RFID) is and how it works. The benefits of this technology to retailers are outlined in contrast to Bar Coding. Though the technology offers promise for retailers, it does present a number of concerns, which are outlined. Lastly, the article identifies research needs with regard to the new technology

Space Medicine Issues and Healthcare Systems for Space Exploration Medicine

This viewgraph presentation reviews issues of health care in space. Some of the issues reviewed are: (1) Physiological adaptation to microgravity, partial gravity, (2) Medical events during spaceflight, (3) Space Vehicle and Environmental and Surface Health Risks, (4) Medical Concept of Operations (CONOPS), (4a) Current CONOPS & Medical Hardware for Shuttle (STS) and ISS, (4b) Planned Exploration Medical CONOPS & Hardware needs, (5) Exploration Plans for Lunar Return Mission & Mars, and (6) Developing Medical Support Systems

Network-mediated encoding of circadian time: The suprachiasmatic nucleus (SCN) from genes to neurons to circuits, and back

The transcriptional architecture of intracellular circadian clocks is similar across phyla, but in mammals interneuronal mechanisms confer a higher level of circadian integration. The suprachiasmatic nucleus (SCN) is a unique model to study these mechanisms, as it operates as a ∼24 h clock not only in the living animal, but also when isolated in culture. This “clock in a dish” can be used to address fundamental questions, such as how intraneuronal mechanisms are translated by SCN neurons into circuit-level emergent properties and how the circuit decodes, and responds to, light input. This review addresses recent developments in understanding the relationship between electrical activity, [Ca(2+)](i), and intracellular clocks. Furthermore, optogenetic and chemogenetic approaches to investigate the distinct roles of neurons and glial cells in circuit encoding of circadian time will be discussed, as well as the epigenetic and circuit-level mechanisms that enable the SCN to translate light input into coherent daily rhythms

Gas dynamics of a luminous zz = 6.13 quasar ULAS J1319++0950 revealed by ALMA high resolution observations

We present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum and [C II] 158 $\mu$m fine structure line emission towards a far-infrared-luminous quasar, ULAS J131911.29$+$095051.4 at $z=6.13$, and combine the new Cycle 1 data with ALMA Cycle 0 data. The combined data have an angular resolution $\sim$ $0.3$, and resolve both the dust continuum and the [C II] line emission on few kpc scales. The [C II] line emission is more irregular than the dust continuum emission which suggests different distributions between the dust and [C II]-emitting gas. The combined data confirm the [C II] velocity gradient that we previously detected in lower resolution ALMA image from Cycle 0 data alone. We apply a tilted ring model to the [C II] velocity map to obtain a rotation curve, and constrain the circular velocity to be 427 $\pm$ 55 km s$^{-1}$ at a radius of 3.2 kpc with an inclination angle of 34$^\circ$. We measure the dynamical mass within the 3.2 kpc region to be 13.4$_{-5.3}^{+7.8}$ $\times 10^{10}\,M_{\odot}$. This yields a black hole and host galaxy mass ratio of 0.020$_{-0.007}^{+0.013}$, which is about 4$_{-2}^{+3}$ times higher than the present-day $M_{\rm BH}$/$M_{\rm bulge}$ ratio. This suggests that the supermassive black hole grows the bulk of its mass before the formation of the most of stellar mass in this quasar host galaxy in the early universe.Comment: 24 pages, 5 figures, accepted for publication in Ap

Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska

Beavers are starting to colonize low arctic tundra regions in Alaska and Canada, which hasimplications for surface water changes and ice-rich permafrost degradation. In this study, weassessed the spatial and temporal dynamics of beaver dam building in relation to surface waterdynamics and thermokarst landforms using sub-meter resolution satellite imagery acquiredbetween 2002 and 2019 for two tundra areas in northwestern Alaska. In a 100 km2study area nearKotzebue, the number of dams increased markedly from 2 to 98 between 2002 and 2019. In a430 km2study area encompassing the entire northern Baldwin Peninsula, the number of damsincreased from 94 to 409 between 2010 and 2019, indicating a regional trend. Correlating data onbeaver dam numbers with surface water area mapped for 12 individual years between 2002 and2019 for the Kotzebue study area showed a significant positive correlation (R2=0.61; p < .003).Beaver-influenced waterbodies accounted for two-thirds of the 8.3% increase in total surface waterareain the Kotzebue study area during the 17 year period. Beavers specifically targeted thermokarstlandforms in their dam building activities. Flooding of drained thermokarst lake basins accountedfor 68% of beaver-influenced surface water increases, damming of lake outlets accounted for 26%,and damming of beaded streams accounted for 6%. Surface water increases resulting from beaverdam building likely exacerbated permafrost degradation in the region, but dam failure alsofactored into the drainage of several thermokarst lakes in the northern Baldwin Peninsula studyregion, which could promote local permafrost aggradation in freshly exposed lake sediments. Ourfindings highlight that beaver-driven ecosystem engineering must be carefully considered whenaccounting for changes occurring in some permafrost regions, and in particular, regional surfacewater dynamics in low Arctic and Boreal landscapes

Embedding the Pentagon

The Pentagon Model is an explicit supersymmetric extension of the Standard Model, which involves a new strongly-interacting SU(5) gauge theory at TeV-scale energies. We show that the Pentagon can be embedded into an SU(5) x SU(5) x SU(5) gauge group at the GUT scale. The doublet-triplet splitting problem, and proton decay compatible with experimental bounds, can be successfully addressed in this context. The simplest approach fails to provide masses for the lighter two generations of quarks and leptons; however, this problem can be solved by the addition of a pair of antisymmetric tensor fields and an axion.Comment: 39 page

Incorporating transparency into the governance of deep-seabed mining in the Area beyond national jurisdiction

In the governance of natural resources, transparency has been linked to improved accountability, as well as enforceability, compliance, sustainability, and ultimately more equitable outcomes. Here, good practices in transparency relevant to the emerging governance of deep-seabed mining in the Area beyond national jurisdiction are identified and compared with current practices of the International Seabed Authority (ISA). The analysis found six areas of good transparency practice that could improve the accountability of deep-seabed mining: i) access to information; ii) reporting; iii) quality assurance; iv) compliance information / accreditation; v) public participation; and vi) ability to review / appeal decisions. The ISA has in some instances adopted progressive practices regarding its rules, regulations, and procedures (e.g. including the precautionary approach). However, the results here show that overall the ISA will need to consider improvements in each of the six categories above, in order to reflect contemporary best transparency practices, as well as meeting historical expectations embodied in the principle of the ‘common heritage of mankind’. This would involve a revision of its rules and procedures. The ongoing review and drafting of the ISA’s deep-seabed mining exploitation regulations offers a once-in-a-generation opportunity to improve upon the current situation. Findings from this analysis are summarised in 18 recommendations, including publication of annual reports submitted by contractors, publication of annual financial statements, development of a transparency policy, compliance reporting, and dedicated access to Committee meetings