Busy Beaver Scores and Alphabet Size

We investigate the Busy Beaver Game introduced by Rado (1962) generalized to non-binary alphabets. Harland (2016) conjectured that activity (number of steps) and productivity (number of non-blank symbols) of candidate machines grow as the alphabet size increases. We prove this conjecture for any alphabet size under the condition that the number of states is sufficiently large. For the measure activity we show that increasing the alphabet size from two to three allows an increase. By a classical construction it is even possible to obtain a two-state machine increasing activity and productivity of any machine if we allow an alphabet size depending on the number of states of the original machine. We also show that an increase of the alphabet by a factor of three admits an increase of activity

Could resource rents finance universal access to infrastructure? A first exploration of needs and rents

It is often argued that, ethically, resource rents should accrue to all citizens. Yet, in reality, the rents from exploiting national resources are often concentrated in the hands of a few. If resource rents were to be taxed, on the other hand, substantial amounts of public money could be raised and used to cover the population's infrastructure needs, such as access to electricity, water, sanitation, communication technology and roads, which all play important roles in a nation's economic development process. Here, the authors examine to what extent existing resource rents could be used to provide universal access to these infrastructures

Carbon Pricing Revenues Could Close Infrastructure Access Gaps

Introducing a price on greenhouse gas emissions would not only contribute to reducing the risk of dangerous anthropogenic climate change, but would also generate substantial public revenues. Some of these revenues could be used to cover investment needs for infrastructure providing access to water, sanitation, electricity, telecommunications, and transport. In this way, emission pricing could promote sustainable socio-economic development by safeguarding the stability of natural systems which constitute the material basis of economies, while at the same time providing public goods that are essential for human well-being. For a scenario that is consistent with limiting global warming to below 2°C, we find that domestic carbon pricing (without redistribution of revenues across countries) has substantial potential to close existing access gaps for water, sanitation, electricity, and telecommunication. However, for the majority of countries carbon pricing revenues would not be sufficient to pave all unpaved roads, and for most countries in Sub-Saharan Africa they would be insufficient to provide universal access to all types of infrastructure except water. If some fraction of the global revenues of carbon pricing is redistributed, e.g., via the Green Climate Fund, more ambitious infrastructure access goals could be achieved in developing countries. Our paper also bears relevance for the design of climate finance mechanisms, as it suggests that supporting carbon pricing policies instead of project based finance might not only permit cost-efficient emission reductions, but also leverage public revenues to promote human development goals

Instability of a Supersonic Boundary-Layer with Localized Roughness

A localized 3-D roughness causes boundary-layer separation and (weak) shocks. Most importantly, streamwise vortices occur which induce streamwise (low U, high T) streaks. Immersed boundary method (volume force) suitable to represent roughness element in DNS. Favorable comparison between bi-global stability theory and DNS for a "y-mode" Outlook: Understand the flow physics (investigate "z-modes" in DNS through sinuous spanwise forcing, study origin of the beat in DNS)

Techno-economic assessment guidelines for CO2 utilization

Carbon Capture and Utilization (CCU) is an emerging technology field that can replace fossil carbon value chains, and that has a significant potential to achieve emissions mitigation or even “negative emissions”—however in many cases with challenging technology feasibility and economic viability. Further challenges arise in the decision making for CCU technology research, development, and deployment, in particular when allocating funding or time resources. No generally accepted techno-economic assessment (TEA) standard has evolved, and assessment studies often result in “apples vs. oranges” comparisons, a lack of transparency and a lack of comparability to other studies. A detailed guideline for systematic techno-economic (TEA) and life cycle assessment (LCA) for CCU technologies was developed; this paper shows a summarized version of the TEA guideline, which includes distinct and prioritized (shall and should) rules and which allows conducting TEA in parallel to LCA. The TEA guideline was developed in a co-operative and creative approach with roughly 50 international experts and is based on a systematic literature review as well as on existing best practices from TEA and LCA from the areas of industry, academia, and policy. To the best of our knowledge, this guideline is the first TEA framework with a focus on CCU technologies and the first that is designed to be conducted in parallel to LCA due to aligned vocabulary and assessment steps, systematically including technology maturity. Therefore, this work extends current literature, improving the design, implementation, and reporting approaches of TEA studies for CCU technologies. Overall, the application of this TEA guideline aims at improved comparability of TEA studies, leading to improved decision making and more efficient allocation of funds and time resources for the research, development, and deployment of CCU technologies

Postglacial evolution of Lake Constance: sedimentological and geochemical evidence from a deep-basin sediment core

The modern, over 250-m-deep basin of Lake Constance represents the underfilled northern part of an over 400-m-deep, glacially overdeepened trough, which reaches well into the Alps at its southern end. The overdeep- ening was formed by repeated glacial advance-retreat cycles of the Rhine Glacier throughout the Middle to Late Pleistocene. A seismic survey of Lake Constance revealed a Quaternary sediment fill of more than 150 m thickness representing at least the last glacial cycle. The stratified sedimentary fill consists at the base of ice-contact deposits on top of the molasse bedrock, overlain by glaciolacustrine to lacustrine sediments. During the successful field test of a newly developed, mid-size coring system ("HIPERCORIG"), the longest core (HIBO19) ever taken in Lake Constance was retrieved with an overall length of 24 m. The sediments recovered consist of a nearly continuous succession of lacustrine silts and sands including more than 12 m of Late Glacial sediment at the base. 14 lithotypes were identified through petrophysical and geochemical analyses. In combination with a 14C- and OSL-based age-depth model, the core was divided into three main chronostratigraphic units. The basal age of ~ 13.7 ka BP dates the base of the succes- sion back to the Bølling-Allerød interstadial, with overlying strata representing a complete and thick Younger-Dryas to Holocene succession. The sediments offer a high-resolution insight into the evolution of paleo-Lake Constance from a cold, postglacial to a more productive and warmer Holocene lake. The Late Glacial succession is dominated by massive, m-thick sand beds reflecting episodic sedimentation pulses. They are most likely linked to a subaquatic channel system originating in the river Seefelder Aach, which is, despite the Holocene drape, still apparent in today’s lake bathymetry. The overlying Holocene succession reveals a prominent, several cm-thick, double-turbiditic event layer representing the most distal impact of the Flimser Bergsturz, the largest known rockslide of the Alps that occurred over 100 km upstream the river Rhine at ~ 9.5 ka BP. Furthermore, lithologic variations in the Holocene succession document the varying sediment loads of the river Rhine and the endogenic production representing a multitude of environmental changes

A Mouse Model of Heritable Cerebrovascular Disease

The study of animal models of heritable cerebrovascular diseases can improve our understanding of disease mechanisms, identify candidate genes for related human disorders, and provide experimental models for preclinical trials. Here we describe a spontaneous mouse mutation that results in reproducible, adult-onset, progressive, focal ischemia in the brain. The pathology is not the result of hemorrhage, embolism, or an anatomical abnormality in the cerebral vasculature. The mutation maps as a single site recessive locus to mouse Chromosome 9 at 105 Mb, a region of shared synteny with human chromosome 3q22. The genetic interval, defined by recombination mapping, contains seven protein-coding genes and one processed transcript, none of which are changed in their expression level, splicing, or sequence in affected mice. Targeted resequencing of the entire interval did not reveal any provocative changes; thus, the causative molecular lesion has not been identified

Multilevel Monte Carlo methods

The author's presentation of multilevel Monte Carlo path simulation at the MCQMC 2006 conference stimulated a lot of research into multilevel Monte Carlo methods. This paper reviews the progress since then, emphasising the simplicity, flexibility and generality of the multilevel Monte Carlo approach. It also offers a few original ideas and suggests areas for future research

Effects of moderate alcohol levels on default mode network connectivity in heavy drinkers

Background It is well established that even moderate levels of alcohol affect cognitive functions such as memory, self-related information processing, and response inhibition. Nevertheless, the neural mechanisms underlying these alcohol-induced changes are still unclear, especially on the network level. The default mode network (DMN) plays an important role in memory and self-initiated mental activities; hence, studying functional interactions of the DMN may provide new insights into the neural mechanisms underlying alcohol-related changes. Methods We investigated resting-state functional connectivity (rsFC) of the DMN in a cohort of 37 heavy drinkers at a breath alcohol concentration of 0.8 g/kg. Alcohol and saline were infused in a single-blind crossover design. Results Intranetwork connectivity analyses revealed that participants showed significantly decreased rsFC of the right hippocampus and right middle temporal gyrus during acute alcohol exposure. Moreover, follow-up analyses revealed that these rsFC decreases were more pronounced in participants who reported stronger craving for alcohol. Exploratory internetwork connectivity analyses of the DMN with other resting-state networks showed no significant alcohol-induced changes, but suffered from low statistical power. Conclusions Our results indicate that acute alcohol exposure affects rsFC within the DMN. Functionally, this finding may be associated with impairments in memory encoding and self-referential processes commonly observed during alcohol intoxication. Future resting-state functional magnetic resonance imaging studies might therefore also investigate memory function and test whether DMN-related connectivity changes are associated with alcohol-induced impairments or craving