In the 1960s and 1970s a series of observations and theoretical developments highlighted the presence of several anomalies which could, in principle, be explained by postulating one of the following two working hypotheses: (i) the existence of dark matter, or (ii) the modification of standard gravitational dynamics in low accelerations. In the years that followed, the dark matter hypothesis as an explanation for dark matter phenomenology attracted far more attention compared to the hypothesis of modified gravity, and the latter is largely regarded today as a non-viable alternative. The present article takes an integrated history and philosophy of science approach in order to identify the reasons why the scientific community mainly pursued the dark matter hypothesis in the years that followed, as opposed to modified gravity. A plausible answer is given in terms of three epistemic criteria for the pursuitworthiness of a hypothesis: (a) its problem-solving potential, (b) its compatibility with established theories and the feasibility of incorporation, and (c) its independent testability. A further comparison between the problem of dark matter and the problem of dark energy is also presented, explaining why in the latter case the situation is different, and modified gravity is still considered a viable possibility.
Natural selection has produced an extraordinary diversity of life histories spanning many orders of magnitude in body size, vital rates, and biological times. In general, big and cold organisms grow and reproduce slowly and live long lives; small and warm organisms grow and reproduce quickly and live short lives. The Metabolic Theory of Ecology (MTE) predicts equal and opposite scaling exponents of mass-specific biological rates (e.g., respiration, growth, and reproduction) and times (e.g., development, lifespan, and generation) as a function of size. However, empirical support for these predictions varies depending on trait and taxon. Here I: 1) provide background and mixed support for the quarter-power scaling exponents for life history rates and times predicted by MTE, 2) discuss possible explanations, including effects of natural selection on taxonomic and functional groups, and inadequate data for life history traits, 3) briefly summarize the Equal Fitness Paradigm (EFP) as a unifying theory of bioenergetics, life history and demography that does not depend on any particular allometric scalings, and 4) discuss ramifications of the EFP for other biological phenomena, including physiological performance metrics and trophic energetics of ecosystems. I draw mostly from my knowledge of mammals, yet in many cases the mammalian examples can be generalized to other organisms. I end with prospects for further evaluating and extending the EFP.
El artículo trata de la importancia de las cortes reales, sobre todo las de Juan II de Castilla y de Alfonso V de Aragón, para la recuperación de las obras de Séneca en latín y en traducción. En el Nápoles aragonés, al amparo del magisteriumpolítico-intelectual de los humanistas italianos vinculados con la corte aragonesa, el pensamiento filosófico senequiano se convirtió en un componente de cierto peso para la utilización de la herencia clásica en la gestión de la res publica y la formación de la biblioteca real como instrumentum regni. En la corte castellana el usufructo de la lectio Senecae siguió acomodándose a lo postulado por Alfonso de Cartagena en el prólogo a sus traducciones de los libros de Séneca, es decir, a la necesidad de una interpretación escolástica y profesional para bien entender sus escritos, especialmente en lo referido a cuestiones éticas y dialécticas sensibles.
Diffusion on graphs is ubiquitous with numerous high-impact applications. In these applications, complete diffusion histories play an essential role in terms of identifying dynamical patterns, reflecting on precaution actions, and forecasting intervention effects. Despite their importance, complete diffusion histories are rarely available and are highly challenging to reconstruct due to ill-posedness, explosive search space, and scarcity of training data. To date, few methods exist for diffusion history reconstruction. They are exclusively based on the maximum likelihood estimation (MLE) formulation and require to know true diffusion parameters. In this paper, we study an even harder problem, namely reconstructing Diffusion history from A single SnapsHot} (DASH), where we seek to reconstruct the history from only the final snapshot without knowing true diffusion parameters. We start with theoretical analyses that reveal a fundamental limitation of the MLE formulation. We prove: (a) estimation error of diffusion parameters is unavoidable due to NP-hardness of diffusion parameter estimation, and (b) the MLE formulation is sensitive to estimation error of diffusion parameters. To overcome the inherent limitation of the MLE formulation, we propose a novel barycenter formulation: finding the barycenter of the posterior distribution of histories, which is provably stable against the estimation error of diffusion parameters. We further develop an effective solver named DIffusion hiTting Times with Optimal proposal (DITTO) by reducing the problem to estimating posterior expected hitting times via the Metropolis--Hastings Markov chain Monte Carlo method (M--H MCMC) and employing an unsupervised graph neural network to learn an optimal proposal to accelerate the convergence of M--H MCMC. We conduct extensive experiments to demonstrate the efficacy of the proposed method.
Predicting the future trajectory of a person remains a challenging problem, due to randomness and subjectivity of human movement. However, the moving patterns of human in a constrained scenario typically conform to a limited number of regularities to a certain extent, because of the scenario restrictions and person-person or person-object interactivity. Thus, an individual person in this scenario should follow one of the regularities as well. In other words, a person's subsequent trajectory has likely been traveled by others. Based on this hypothesis, we propose to forecast a person's future trajectory by learning from the implicit scene regularities. We call the regularities, inherently derived from the past dynamics of the people and the environment in the scene, scene history. We categorize scene history information into two types: historical group trajectory and individual-surroundings interaction. To exploit these two types of information for trajectory prediction, we propose a novel framework Scene History Excavating Network (SHENet), where the scene history is leveraged in a simple yet effective approach. In particular, we design two components: the group trajectory bank module to extract representative group trajectories as the candidate for future path, and the cross-modal interaction module to model the interaction between individual past trajectory and its surroundings for trajectory refinement. In addition, to mitigate the uncertainty in ground-truth trajectory, caused by the aforementioned randomness and subjectivity of human movement, we propose to include smoothness into the training process and evaluation metrics. We conduct extensive evaluations to validate the efficacy of our proposed framework on ETH, UCY, as well as a new, challenging benchmark dataset PAV, demonstrating superior performance compared to state-of-the-art methods.
Quantum entanglement is a key resource, which grants quantum systems the ability to accomplish tasks that are classically impossible. Here, we apply Feynman's sum-over-histories formalism to interacting bipartite quantum systems and introduce entanglement measures for bipartite quantum histories. Based on the Schmidt decomposition of the matrix comprised of the Feynman propagator complex coefficients, we prove that bipartite quantum histories are entangled if and only if the Schmidt rank of this matrix is larger than 1. The proposed approach highlights the utility of using a separable basis for constructing the bipartite quantum histories and allows for quantification of their entanglement from the complete set of experimentally measured sequential weak values. We then illustrate the non-classical nature of entangled histories with the use of Hardy's overlapping interferometers and explain why local hidden variable theories are unable to correctly reproduce all observable quantum outcomes. Our theoretical results elucidate how the composite tensor product structure of multipartite quantum systems is naturally extended across time and clarify the difference between quantum histories viewed as projection operators in the history Hilbert space or viewed as chain operators and propagators in the standard Hilbert space.
Knowledge graphs have been adopted in many diverse fields for a variety of purposes. Most of those applications rely on valid and complete data to deliver their results, pressing the need to improve the quality of knowledge graphs. A number of solutions have been proposed to that end, ranging from rule-based approaches to the use of probabilistic methods, but there is an element that has not been considered yet: the edit history of the graph. In the case of collaborative knowledge graphs (e.g., Wikidata), those edits represent the process in which the community reaches some kind of fuzzy and distributed consensus over the information that best represents each entity, and can hold potentially interesting information to be used by knowledge graph refinement methods. In this paper, we explore the use of edit history information from Wikidata to improve the performance of type prediction methods. To do that, we have first built a JSON dataset containing the edit history of every instance from the 100 most important classes in Wikidata. This edit history information is then explored and analyzed, with a focus on its potential applicability in knowledge graph refinement tasks. Finally, we propose and evaluate two new methods to leverage this edit history information in knowledge graph embedding models for type prediction tasks. Our results show an improvement in one of the proposed methods against current approaches, showing the potential of using edit information in knowledge graph refinement tasks and opening new promising research lines within the field.
The history of the Romanian (Rm.) term boier (a medieval aristocratic title) is long and rather confusing. Practically, all dictionaries that include entries on that term present it as ultimately derived from Old Church Slavonic (OCS) bolʹarinʺ. The latter, in its turn, has been presented – in keeping with a suggestion coming from Miklosich – as a “Turanian” word borrowed by South-Danubian Slavs from their Turkic (Bolgar) ruling elite of the 7th – 9th centuries. The present author considers, however, that the mainstream etymologic interpretations of Rm. boier and of its putative OCS source-word are hardly tenable. Part I of this study provides a inguisticethnologic-historical background for a new hypothesis, which does not center on the above-mentioned OCS term (as supposedly borrowed from Turkic), but rather on the deeply-rooted tradition of boyarship in Romania and on two lexical families that display striking correspondence (in roots and suffixes), namely Romanian boiér-boiereásăboieréşte-boieríe-boierí and Albanian bujár-bujoréshë-bujarísht-bujarí-bujerój. Worthy of attention is the fact that the latter lexical family appears to be etymologically linked with the Albanian verb buj ‘to lodge, to take up one’s lodging’, a word for which Gustav Meyer – in his etymologic dictionary of Albanian, 1891 – indicated a significant series of Old Germanic cognates. (Actually, Alb. buj may be a borrowing proper, from Old Germanic, like several other Albanian words for which the respective origin has already been demonstrated.) Such facts open the way for a discussion on the probable connection between the medieval Southeast European boyarship and the Roman institution of hospitalitas, whose earliest beneficiaries were East Germanic foederati. Further arguments along that line – as well as final conclusions – will make up part II of the present study, to be published in a future issue of Arheologia Moldovei.
Germanic tribes from the other bank of the Rhine River progressively settled where the Eburones, annihilated by Caesar in 53 BCE., lived. Among them, the Ubii. Migrating by waves after 38 BCE. to the frontier of the Roman Empire, they built new political and social structures and new religious practices while they appropriated roman culture and habits. Among the cults in the newly created Civitas Ubiorum, the cult to the Matronae, concentrated in the east of the Civitas, became central and dominant. The militaries and the elites were key agents in the circulation of the Matronae. Other social groups, inserted in the curiae, participated in the municipalisation of the cult while those social groups became civic institutions in the civitas then.Born in rural communities in the 1st century CE. before reaching the Roman colonies at the very end of that century, the cult to Matronae spread on a double scheme: some very local cults to some Matronae in small sanctuaries which sometimes revealed a massive amount of inscriptions and a provincial cult to the Matronae Aufaniae that spreads from Bonn and Köln. Through that process, the Matronae were the most revered deities in Germania Inferior, without any other cult able to equal them.
Yaklaşık olarak 997-1043 yılları arasında yaşamış olan Georgios Maniakes, II. Basileos ve Aleksios Komnenos arasındaki dönemin en önemli komutanlarından birisidir. Tarih eserlerinde adı ilk olarak 1030 yılında Telukh temasının strategosu olarak geçen Maniakes, doğuda kazandığı başarıların ardından iki defa İtalya’ya gönderilmiş ve her defasında bu bölgede Bizans İmparatorluğu’nun topraklarını ve nüfuzunu arttırmıştır. Ancak burada bulunduğu iki dönemin sonunda da haksızlıklara uğrayan Maniakes en sonunda isyan ederek İmparator Konstantinos Monomakhos’a karşı harekete geçmiştir. İmparatorluk ordusuyla yapılan muharebede, kaynakların belirttiğine göre neredeyse galip gelmekte olan Maniakes, nereden geldiği bilinmeyen bir mızrak darbesi ile hayatını kaybetmiştir. Bizans, Latin ve Ermeni kaynaklarında kendisiyle ilgili bilgiler verilen Maniakes, bir Viking sagasında da konu edinilmiştir. Yiğitliği, cesareti ve askerlik yeteneği ile elde ettiği başarıları sonucunda yaşadığı dönem için büyük bir iz bırakmış olan Maniakes, nihayetinde bir isyancı olduğu halde, Bizans kaynaklarında neredeyse bir kahraman gibi betimlenmiştir. Bu çalışmada Georgios Maniakes’in hayatının yanında kökeni konusu örneğindeki gibi birtakım tartışmalar irdelenmiş, bunun yanında Maniakes ile ilgili Bizans tarih yazarlarının anlatımlarına yer verilmiş ve onun Bizans tarih yazımındaki yeri hususunda görüşler bildirilmiştir.
A light higgsino is strongly favored by the naturalness, while as a dark matter candidate it is usually under-abundant. We consider the higgsino production in a non-standard history of the universe, caused by a scalar field with an initially displaced vacuum. We find that given a proper reheating temperature induced by the scalar decay, a light higgsino could provide the correct dark matter relic abundance. On the other hand, a sub-TeV higgsino dark matter, once observed, would be a strong hint of the non-standard thermal history of the universe.
The recently proposed Trans-Planckian Censorship Conjecture (TCC) can be used to constrain the energy scale of inflation. The conclusions however depend on the assumptions about post-inflationary history of the Universe. E.g. in the standard case of a thermal post-inflationary history in which the Universe stays radiation dominated at all times from the end of inflation to the epoch of radiation matter equality, TCC has been used to argue that the Hubble parameter during inflation, $H_{\inf}$, is below ${\cal O}(0.1) ~{\rm GeV}$. Cosmological scenarios with a non-thermal post-inflationary history are well-motivated alternatives to the standard picture and it is interesting to find out the possible constraints which TCC imposes on such scenarios. In this work, we find out the amount of enhancement of the TCC compatible bound on $H_{\inf}$ if post-inflationary history before nucleosynthesis was non-thermal. We then argue that if TCC is correct, for a large class of scenarios, it is not possible for the Universe to have undergone a phase of moduli domination.
Software Reliability has just passed the 50-year milestone as a technical discipline along with Software Engineering. This paper traces the roots of Software Reliability Engineering (SRE) from its pre-software history to the beginnings of the field with the first software reliability model in 1967 through its maturation in the 1980s to the current challenges in proving application reliability on smartphones and in other areas. This history began as a thesis proposal for a History of Science research program and includes multiple previously unpublished interviews with founders of the field. The project evolved to also provide a survey of the development of SRE from notable prior histories and from citations of new work in the field including reliability applications to Agile Methods. This history concludes at the modern-day providing bookends in the theory, models, literature, and practice of Software Reliability Engineering from 1968 to 2018 and pointing towards new opportunities to deepen and broaden the field.
We propose a history state formalism for a Dirac particle. By introducing a reference quantum clock system it is first shown that Dirac's equation can be derived by enforcing a timeless Wheeler-DeWitt-like equation for a global state. The Hilbert space of the whole system constitutes a unitary representation of the Lorentz group with respect to a properly defined invariant product, and the proper normalization of global states directly ensures standard Dirac's norm. Moreover, by introducing a second quantum clock, the previous invariant product emerges naturally from a generalized continuity equation. The invariant parameter $τ$ associated with this second clock labels history states for different particles, yielding an observable evolution in the case of an hypothetical superposition of different masses. Analytical expressions for both space-time density and electron-time entanglement are provided for two particular families of electron's states, the former including Pryce localized particles.
Music history, referring to the records of users' listening or downloading history in online music services, is the primary source for music service providers to analyze users' preferences on music and thus to provide personalized recommendations to users. In order to engage users into the service and to improve user experience, it would be beneficial to provide visual analyses of one user's music history as well as visualized recommendations to that user. In this paper, we take a user-centric approach to the design of such visual analyses. We start by investigating user needs on such visual analyses and recommendations, then propose several different visualization schemes, and perform a pilot study to collect user feedback on the designed schemes. We further conduct user studies to verify the utility of the proposed schemes, and the results not only demonstrate the effectiveness of our proposed visualization, but also provide important insights to guide the visualization design in the future.
This paper presents sufficient conditions for the convergence of online estimation methods and the stability of adaptive control strategies for a class of history dependent, functional differential equations. The study is motivated by the increasing interest in estimation and control techniques for robotic systems whose governing equations include history dependent nonlinearities. The functional differential equations in this paper are constructed using integral operators that depend on distributed parameters. As a consequence the resulting estimation and control equations are examples of distributed parameter systems whose states and distributed parameters evolve in finite and infinite dimensional spaces, respectively. suWell-posedness, existence, and uniqueness are discussed for the class of fully actuated robotic systems with history dependent forces in their governing equation of motion. By deriving rates of approximation for the class of history dependent operators in this paper, sufficient conditions are derived that guarantee that finite dimensional approximations of the online estimation equations converge to the solution of the infinite dimensional, distributed parameter system. The convergence and stability of a sliding mode adaptive control strategy for the history dependent, functional differential equations is established using Barbalat's lemma.
Review to Simbor i Roig, Vicent, Ironies de la Modernitat. La ironia del Modernisme al Noucentisme, Barcelona, Publicacions de l’Abadia de Montserrat, 2016, 280 pp., ISBN: 978-84-9883-811-4
The early history of the Vogt-Russell theorem is retraced following its route starting at the realization of a correlation between mass and luminosity of binary and pulsating stars, through the embossing of this observation into a theorem, and finally to the emerging first signs of its failure to serve as a theorem in the strict mathematical sense of the word.