218 research outputs found

    Agnesi Weighting for the Measure Problem of Cosmology

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    The measure problem of cosmology is how to assign normalized probabilities to observations in a universe so large that it may have many observations occurring at many different spacetime locations. I have previously shown how the Boltzmann brain problem (that observations arising from thermal or quantum fluctuations may dominate over ordinary observations if the universe expands sufficiently and/or lasts long enough) may be ameliorated by volume averaging, but that still leaves problems if the universe lasts too long. Here a solution is proposed for that residual problem by a simple weighting factor 1/(1+t^2) to make the time integral convergent. The resulting Agnesi measure appears to avoid problems other measures may have with vacua of zero or negative cosmological constant.Comment: 26 pages, LaTeX; discussion is added of how Agnesi weighting appears better than other recent measure

    Cosmological Measures without Volume Weighting

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    Many cosmologists (myself included) have advocated volume weighting for the cosmological measure problem, weighting spatial hypersurfaces by their volume. However, this often leads to the Boltzmann brain problem, that almost all observations would be by momentary Boltzmann brains that arise very briefly as quantum fluctuations in the late universe when it has expanded to a huge size, so that our observations (too ordered for Boltzmann brains) would be highly atypical and unlikely. Here it is suggested that volume weighting may be a mistake. Volume averaging is advocated as an alternative. One consequence may be a loss of the argument that eternal inflation gives a nonzero probability that our universe now has infinite volume.Comment: 15 pages, LaTeX, added references for constant-H hypersurfaces and also an idea for minimal-flux hypersurface

    Application of Large-Scale Synthetic Power System Models for Energy Economic Studies

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    Due to information confidentiality issues, there is limited access to actual power system models that represent features of actual power grids for teaching, training, and research purposes. The authors\u27 previous work describes the process of creating synthetic transmission networks, with statistics similar to those of actual power grids. Thus, this paper outlines a systematic methodology to augment the synthetic network base case for energy economic studies. The key step is to determine generator cost models by fuel type and capacity. Based on statistics summarized from the actual grids, two approaches are proposed to assign coefficients to generator cost models. To illustrate the proposed creation procedure, we describe the construction of a synthetic model for Electric Reliability Council of Texas footprint. Simulation results are presented to verify that the created test system is able to represent the behavior of actual power systems

    Children's informal learning at home during COVID-19 lockdown

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    The national COVID-19 lockdown during school Term 1 2020 provided a unique context to investigate children’s experiences of informal, everyday learning in their household bubble. In Terms 3 and 4, 178 children in Years 4–8 from 10 primary schools agreed to participate in a group art-making activity and an individual interview about their experiences. The research adopted a strengths-based approach on the basis that most children are capable actors in their social worlds. This report documents children’s accounts of the multiple ways in which they negotiated the novel experience of forced confinement over a period of several weeks with family and whānau. The report is rich with children’s own accounts of their everyday living and learning during lockdown. To foreground children’s descriptions and explanations of their lockdown experience in this way is an acknowledgement of their right to express their views on matters of interest to them in their lives, and to have those views listened to, and acted on, by adults. Similarly, the approach reflects a growing educational research interest in student voice: enabling children to articulate their experiences so that adults can use this knowledge to better respond to and support children’s learning aspirations and needs. This research report does not speak for all children or all children’s experiences. Nevertheless, it does provide valuable insights about the phenomenon of children’s informal and everyday learning during lockdown, gained from a group of children for whom it was a mostly positive experience, and through which they learned much about themselves as persons and as members of a family and whānau. Several months after the event, children in this study were able and willing to recall their experiences of learning during lockdown. They could identify social, cultural, and historical dimensions of their learning at home. Some children were able to recount rich, detailed stories about their lockdown experience and the ways in which they organised their days and activities. For some others, their days were largely shaped for them by family and whānau members, but even so, the children were able to explain what they enjoyed, or did not, and why. Variations in children’s learning across the group highlighted the complexity of learning that each child experienced, and the importance of having social relations, environments, and contexts that encourage and support their learning. Children demonstrated an understanding and appreciation of the value of this learning.falsehttp://www.nzcer.org.nz/research/publications/learning-during-lockdownNew Zealand Council for Educational Researc

    Russian roulette with unlicensed fat-burner drug 2,4-dinitrophenol (DNP) : evidence from a multidisciplinary study of the internet, bodybuilding supplements and DNP users

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    BACKGROUND: 2,4-Dinitrophenol (DNP) poses serious health-risks to humans. The aims of this three-stage multidisciplinary project were, for the first time, to assess the risks to the general public from fraudulent sale of or adulteration/contamination with DNP; and to investigate motives, reasons and risk-management among DNP-user bodybuilders and avid exercisers. METHODS: Using multiple search-engines and guidance for Internet research, online retailers and bodybuilding forums/blogs were systematically explored for availability of DNP, advice offered on DNP use and user profiles. Ninety-eight pre-workout and weight-loss supplements were purchased and analysed for DNP using liquid-chromatography-mass-spectrometry. Psychosocial variables were captured in an international sample of 35 DNP users (26.06 ± 6.10 years, 94.3 % male) with an anonymous, semi-qualitative self-reported survey. RESULTS: Although an industrial chemical, evidence from the Internet showed that DNP is sold 'as is', in capsules or tablets to suit human consumption, and is used 'uncut'. Analytical results confirmed that DNP is not on the supplement market disguised under fictitious supplement names, but infrequently was present as contaminant in some supplements (14/98) at low concentration (<100mcg/kg). Users make conscious and 'informed' decisions about DNP; are well-prepared for the side-effects and show nonchalant attitude toward self-experimentation with DNP. Steps are often taken to ensure that DNP is genuine. Personal experience with performance- and appearance enhancing substances appears to be a gateway to DNP. Advice on DNP and experiences are shared online. The significant discrepancy between the normative perception and the actual visibility suggests that DNP use is-contrary to the Internet accounts-a highly concealed and lonesome activity in real life. Positive experiences with the expected weight-loss prevail over the negative experiences from side effects (all but two users considered using DNP again) and help with using DNP safely is considered preferable over scare-tactics. CONCLUSION: Legislation banning DNP sale for human consumption protects the general public but DNP is sold 'as is' and used 'uncut' by determined users who are not dissuaded from experimenting with DNP based on health threats. Further research with stakeholders' active participation is imperative for targeted, proactive public health policies and harm-reduction measures for DNP, and other illicit supplements

    Key Technical Challenges for the Electric Power Industry and Climate Change

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    This paper, prepared by the Climate Change Technology Subcommittee, a subcommittee of the Power and Energy Society Energy Development and Power Generation Committee, identifies key technical issues facing the electric power industry, related to global climate change. The technical challenges arise from: 1) impacts on system operating strategies, configuration, and expansion plans of emission-reducing technologies; 2) power infrastructure response to extreme weather events; 3) effects of government policies including an expanded use of renewable and alternative energy technologies; and 4) impacts of market rules on power system operation. Possible lessons from other industries\u27 responses to climate change are explored

    The Born Rule Dies

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    The Born rule may be stated mathematically as the rule that probabilities in quantum theory are expectation values of a complete orthogonal set of projection operators. This rule works for single laboratory settings in which the observer can distinguish all the different possible outcomes corresponding to the projection operators. However, theories of inflation suggest that the universe may be so large that any laboratory, no matter how precisely it is defined by its internal state, may exist in a large number of very distantly separated copies throughout the vast universe. In this case, no observer within the universe can distinguish all possible outcomes for all copies of the laboratory. Then normalized probabilities for the local outcomes that can be locally distinguished cannot be given by the expectation values of any projection operators. Thus the Born rule dies and must be replaced by another rule for observational probabilities in cosmology. The freedom of what this new rule is to be is the measure problem in cosmology. A particular volume-averaged form is proposed.Comment: LaTeX, 16 pages, typos in Eqs. (4.3) and (6.2) correcte

    A novel community driven software for functional enrichment analysis of extracellular vesicles data

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    Bioinformatics tools are imperative for the in depth analysis of heterogeneous high-throughput data. Most of the software tools are developed by specific laboratories or groups or companies wherein they are designed to perform the required analysis for the group. However, such software tools may fail to capture “what the community needs in a tool”. Here, we describe a novel community-driven approach to build a comprehensive functional enrichment analysis tool. Using the existing FunRich tool as a template, we invited researchers to request additional features and/or changes. Remarkably, with the enthusiastic participation of the community, we were able to implement 90% of the requested features. FunRich enables plugin for extracellular vesicles wherein users can download and analyse data from Vesiclepedia database. By involving researchers early through community needs software development, we believe that comprehensive analysis tools can be developed in various scientific disciplines
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