Formation of the frozen core in critical Boolean Networks

We investigate numerically and analytically the formation of the frozen core in critical random Boolean networks with biased functions. We demonstrate that a previously used efficient algorithm for obtaining the frozen core, which starts from the nodes with constant functions, fails when the number of inputs per node exceeds 4. We present computer simulation data for the process of formation of the frozen core and its robustness, and we show that several important features of the data can be derived by using a mean-field calculation

Scaling laws in critical random Boolean networks with general in- and out-degree distributions

We evaluate analytically and numerically the size of the frozen core and various scaling laws for critical Boolean networks that have a power-law in- and/or out-degree distribution. To this purpose, we generalize an efficient method that has previously been used for conventional random Boolean networks and for networks with power-law in-degree distributions. With this generalization, we can also deal with power-law out-degree distributions. When the power-law exponent is between 2 and 3, the second moment of the distribution diverges with network size, and the scaling exponent of the nonfrozen nodes depends on the degree distribution exponent. Furthermore, the exponent depends also on the dependence of the cutoff of the degree distribution on the system size. Altogether, we obtain an impressive number of different scaling laws depending on the type of cutoff as well as on the exponents of the in- and out-degree distributions. We confirm our scaling arguments and analytical considerations by numerical investigations

Differing Climatic Mass Balance Evolution Across Svalbard Glacier Regions Over 1900–2010

Relatively little is known about the glacier mass balance of Svalbard in the first half of the twentieth century. Here, we present the first century-long climatic mass balance time series for the Svalbard archipelago. We use a parameterized mass balance model forced by statistically downscaled ERA-20C data to model climatic mass balance for all glacierized areas on Svalbard with a 250 m resolution for the period 1900–2010. Results are presented for the archipelago as a whole and separately for nine different subregions. We analyze the extent to which climatic mass balance in the different subregions mirror the temporal evolution of the climate warming signal, especially during the early twentieth century Arctic warming episode. The spatially averaged mean annual climatic mass balance for all Svalbard is balanced at −0.002 m w.e. with an associated mean equilibrium line altitude of 425 m a.s.l. When also taking calving fluxes into account, this status leads to an archipelago-wide cumulative mass balance of −16.9 m w.e. over the study period, equaling a sea level equivalent of ~1.6 mm. The long-term evolution of climatic mass balance is largely governed by ablation variability. Refreezing contributes 34% to the archipelago-wide mass gain on average. Considerable variability is evident across Svalbard, with predominantly positive climatic mass balances in the northeastern parts of the archipelago and mostly negative ones in the western and southern parts. The archipelago-wide climatic mass balance shows a statistically significant trend of −0.021 m w.e. per decade and the associated equilibrium line altitude rises with a likewise significant trend of +3.0 m a.s.l. per decade. Spatial variability of the equilibrium line is such that the lowest altitudes are reached across the eastern islands of the archipelago and the highest ones in the central parts of Spitsbergen

Emergence of common concepts, symmetries and conformity in agent groups—an information-theoretic model

© 2023 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/The paper studies principles behind structured, especially symmetric, representations through enforced inter-agent conformity. For this, we consider agents in a simple environment who extract individual representations of this environment through an information maximization principle. The representations obtained by different agents differ in general to some extent from each other. This gives rise to ambiguities in how the environment is represented by the different agents. Using a variant of the information bottleneck principle, we extract a ‘common conceptualization’ of the world for this group of agents. It turns out that the common conceptualization appears to capture much higher regularities or symmetries of the environment than the individual representations. We further formalize the notion of identifying symmetries in the environment both with respect to ‘extrinsic’ (birds-eye) operations on the environment as well as with respect to ‘intrinsic’ operations, i.e. subjective operations corresponding to the reconfiguration of the agent’s embodiment. Remarkably, using the latter formalism, one can re-wire an agent to conform to the highly symmetric common conceptualization to a much higher degree than an unrefined agent; and that, without having to re-optimize the agent from scratch. In other words, one can ‘re-educate’ an agent to conform to the de-individualized ‘concept’ of the agent group with comparatively little effort.Peer reviewe

Seed Predation on Oil-Polluted and Unpolluted Vachellia (Acacia) Trees in a Hyper-Arid Desert Ecosystem

Acacia trees are keystone species in many arid environments, supporting high levels of plant and animal diversity. In Israel, the populations of Vachellia (formerly Acacia) tortilis (Forssk.) and V. raddiana (Savi) are declining at an alarming rate. Severe infestations by bruchid beetles (Coleoptera, Chrysomelidae) are among the major causes of seed mortality, but additional environmental stressors can reduce the defence level of the seeds, exacerbating their susceptibility to predators. In a hyper-arid desert ecosystem affected by two major oil spills (in 1975 and 2014), we quantified seed predation rates caused by insect granivores before and after the pods dropped to the ground. We recorded predation rates of up to 84% for both tree species, and higher predation rates at the ground level than in the canopy, suggesting that repeated infestations occur. These results reinforce the call to protect the populations of large ungulates such as gazelles, which kill the bruchids by feeding upon the pods, and promote seed germination and dispersion. We found no clear evidence of a negative effect of the oil spill on seed predation, indicating that oil pollution did not increase the vulnerability of the seeds to granivores even in trees affected by the recent oil spill.Jacob Blaustein Center for Scientific Cooperationinfo:eu-repo/semantics/publishedVersio

Ice thickness distribution and hydrothermal structure of Elfenbeinbreen and Sveigbreen, eastern Spitsbergen, Svalbard

In recent decades, Svalbard glaciers have been widely radioecho sounded. The earliest extensive surveys of ice thickness were the airborne echo soundings carried out in the 1970s and 1980s (Macheret and Zhuravlev, 1982; Dowdeswell and others, 1984). These studies used low-accuracy radar and positioning systems and mostly consisted of a single profile along the centre line of each glacier. Subsequent radar campaigns, mostly ground-based but sometimes also airborne, used increasingly improved radar and positioning systems providing a wider coverage of the glacier surfaces by radar profiles. A complete summary of glaciers on Svalbard with readily available radio-echo sounded ice-thickness data can be found in Martín-Español and others (2015)

Monte Carlo modelling projects the loss of most land-terminating glaciers on Svalbard in the 21st century under RCP 8.5 forcing

The high Arctic archipelagos around the globe are among the most strongly glacierized landscapes on Earth apart from the Greenland and Antarctic ice sheets. Over the past decades, the mass losses from land ice in the high Arctic regions have contributed substantially to global sea level rise. Among these regions, the archipelago of Svalbard showed the smallest mass losses. However, this could change in the coming decades, as Svalbard is expected to be exposed to strong climate warming over the 21st century. Here we present extensive Monte Carlo simulations of the future ice-mass evolution of 29 individual land-terminating glaciers on the Svalbard archipelago under an RCP 8.5 climate forcing. An extrapolation of the 29 sample glaciers to all land-terminating glaciers of the archipelago suggests an almost complete deglaciation of the region by 2100. Under RCP 8.5, 98% of the land-terminating glaciers will have declined to less than one tenth of their initial size, resulting in a loss of 7392 ± 2481 km ^2 of ice coverage

Guiding Design Principle Projects: A Canvas for Young Design Science Researchers

Particularly young researchers face challenges in organizing large design science research (DSR) projects and often struggle to capture, communicate, and reflect on important components to produce purposeful outcomes. Making informed decisions at the project start, such as selecting suitable kernel theories and development procedures, is of great relevance because they affect the entire design process and the resulting design products. Although DSR can produce different types of outcomes, from more situational artifacts to more abstract design knowledge, scholars point to the need for generalizing insights collected in such projects to advance the knowledge base. As design principles are among the prevailing forms of such design knowledge, this paper builds a visual inquiry tool—represented as a canvas—that navigates researchers through common components for crafting design principles and leverages collaborative reflections on essential project decisions. To build our canvas, we adapt inquiry-based learning (IBL) guidelines and visual inquiry tools to DSR education. Evaluations with doctoral students revealed promising indications for the canvas’s applicability and usefulness in guiding iterative DSR projects, reflecting on basic components, and communicating work-in-progress to other scholars and practice. Overall, we complement the body of DSR literature by providing an educational visual inquiry tool for producing design principles

Cutting Carbon Footprint With Smart Tool Management And Cemented Carbide (WC-Co) Upcycling

During the production of a small to medium-sized aircraft, approximately 250,000 rivet holes are required. These must be manufactured according to strict aviation specific technical, quality, and safety standards. High-quality cemented carbide (WC-Co) drilling tools are used to ensure the necessary precision and durability. However, the high energy requirement for production, especially for sintering the WC-Co blanks, and grinding the final tool geometry negatively impacts the carbon footprint of aircraft production. This study aims to analyse the environmental impact of each step in the WC-Co tool production chain and proposes innovative methods to upcycle worn tools without the need of conventional recycling processes. To reduce the climate impact, a novel smart digital tool management system is introduced containing digital twins of the individual tools. This system is complemented with three new methods of upcycling WC-Co drilling tools: regrinding worn tools to smaller diameters, applying a PVD-coating to compensate for diameter deviations, and de- and recoating diamond coatings on WC-Co tools. Preliminary results in modelling the climate impact show that these strategies can reduce the carbon footprint by up to 53 %

EU views on the British vote to leave: Italy, Germany, Slovenia and Spain

In the run-up to the referendum, the LSE BrexitVote blog ran a series setting out the potential positions of various EU member states if Britain voted for leave. Written by authors based at universities and research institutions across Europe, and compiled by the LSE’s Tim Oliver, the series showed the variety of positions and concerns found across the EU. A full list of the views can be found here. In this post authors from Italy, Germany, Slovenia and Spain, each of whom contributed to the original series, give a brief insight into how politics in their country has responded to the British vote to leave the EU