One of the most public episodes of gatekeeping in modern science was the case of so-called 'cold fusion'. At a news conference in 1989 the electrochemists Martin Fleischmann and Stanley Pons announced that they had found evidence of nuclear fusion in palladium electrodes loaded with deuterium. There was worldwide interest. Many groups sought to reproduce the results, most unsuccessfully. Within months, the prevailing view became strongly negative. The claims of Fleischmann and Pons came to be regarded as disreputable, as well as false. As the Caltech physicist David Goldstein put it, cold fusion became 'a pariah field, cast out by the scientific establishment' (Goldstein 1994). The case would already be interesting for students of gatekeeping if the story had ended at that point. Even more interestingly, however, the field survived and persisted. It has been enjoying a modest renaissance, with recent government funding both in the US and the EU. This piece offers an opinionated introduction to cold fusion as a case study of scientific gatekeeping, discussing both its early and recent history
A brief history of the development of surface detectors for the study of the high-energy cosmic rays is presented. The paper is based on an invited talk given at UHECR2022 held in LAquila, October 2022. In a complementary talk, P Sokolsky discussed the development of the fluorescence technique for air-shower detection.
Prediction of ``anyons'', often attributed exclusively to Wilczek, came first from Leinaas & Myrheim in 1977, and independently from Goldin, Menikoff, & Sharp in 1980-81. In 2020, experimentalists successfully created anyonic excitations. This paper discusses why the possibility of quantum particles in two-dimensional space with intermediate exchange statistics eluded physicists for so long after bosons and fermions were understood. The history suggests ideas for the preparation of future researchers. I conclude by addressing failures to attribute scientific achievements accurately. Such practices disproportionately hurt women and minorities in physics, and are harmful to science.
The end-user programming of social robot behavior is usually limited by a predefined set of movements. We are proposing a puppeteering robotic interface that provides a more intuitive method of programming robot expressive movements. As the user manipulates the puppet of a robot, the actual robot replicates the movements, providing real-time visual feedback. Through this proposed interface, even with limited training, a novice user can design and program expressive movements efficiently. We present our preliminary user study results in this extended abstract.
In this work, I explore the concept of quantization as a mapping from classical phase space functions to quantum operators. I discuss the early history of this notion of quantization with emphasis on the works of Schrödinger and Dirac, and how quantization fit into their overall understanding of quantum theory in the 1920's. Dirac, in particular, proposed a quantization map which should satisfy certain properties, including the property that quantum commutators should be related to classical Poisson brackets in a particular way. However, in 1946, Groenewold proved that Dirac's mapping was inconsistent, making the problem of defining a rigorous quantization map more elusive than originally expected. This result, known as the Groenewold-Van Hove theorem, is not often discussed in physics texts, but here I will give an account of the theorem and what it means for potential "corrections" to Dirac's scheme. Other proposals for quantization have arisen over the years, the first major one being that of Weyl in 1927, which was later developed by many, including Groenewold, and which has since become known as Weyl Quantization in the mathematical literature. Another, known as Geometric Quantization, formulates quantization in differential-geometric terms by appealing to the character of classical phase spaces as symplectic manifolds; this approach began with the work of Souriau, Kostant, and Kirillov in the 1960's. I will describe these proposals for quantization and comment on their relation to Dirac's original program. Along the way, the problem of operator ordering and of quantizing in curvilinear coordinates will be described, since these are natural questions that immediately present themselves when thinking about quantization.
The ionization losses -- the losses of energy by fast charged particles traveling through a matter -- have been under study for more than 100 years. The theoretical explanation of this process spans similar period. About 75 years ago, Lev Landau published a theoretical paper on the ionization losses, which drastically leveled up the research and still remains amongst the most cited in the field. The present note digests the history of theoretical development and attempts to clarify Landau's method of research and the function named after him.
Este artículo analiza las contradictorias respuestas que la administración Carazo Odio pretendió impulsar para mitigar la crisis económica de principios de la década de 1980. El objetivo es brindar una reconstrucción parcial del proceso: cómo el gobierno definía la crisis o su incomprensión de esta misma, la insistencia en la retórica de soberanía frente a entes financieros externos, los problemas de liquidez monetaria, los choques entre facciones políticas, entre otros. Es un acercamiento a las dinámicas internas de la política costarricense, enfatizando en sus contradicciones entre democratización y secretismo. Para la elaboración del texto se emplearon documentos del Archivo Nacional del periodo 1978-1982, especialmente, de la Serie Presidencia y Actas del Consejo de Gobierno.
In a previous paper, we showed that a class of time travel paradoxes which cannot be resolved using Novikov's self-consistency conjecture can be resolved by assuming the existence of multiple histories or parallel timelines. However, our proof was obtained using a simplistic toy model, which was formulated using contrived laws of physics. In the present paper we define and analyze a new model of time travel paradoxes, which is more compatible with known physics. This model consists of a traversable Morris-Thorne wormhole time machine in 3+1 spacetime dimensions. We define the spacetime topology and geometry of the model, calculate the geodesics of objects passing through the time machine, and prove that this model inevitably leads to paradoxes which cannot be resolved using Novikov's conjecture, but can be resolved using multiple histories. An open-source simulation of our new model using Mathematica is available for download on GitHub. We also provide additional arguments against the Novikov self-consistency conjecture by considering two new paradoxes, the switch paradox and the password paradox, for which assuming self-consistency inevitably leads to counter-intuitive consequences. Our new results provide more substantial support to our claim that if time travel is possible, then multiple histories or parallel timelines must also be possible.
Camille Jahel, Maxime Lenormand, Ismaila Seck
et al.
In the dominant livestock systems of Sahelian countries herds have to move across territories. Their mobility is often a source of conflict with farmers in the areas crossed, and helps spread diseases such as Rift Valley Fever. Knowledge of the routes followed by herds is therefore core to guiding the implementation of preventive and control measures for transboundary animal diseases, land use planning and conflict management. However, the lack of quantitative data on livestock movements, together with the high temporal and spatial variability of herd movements, has so far hampered the production of fine resolution maps of animal movements. This paper proposes a general framework for mapping potential paths for livestock movements and identifying areas of high animal passage potential for those movements. The method consists in combining the information contained in livestock mobility networks with landscape connectivity, based on different mobility conductance layers. We illustrate our approach with a livestock mobility network in Senegal and Mauritania in the 2014 dry and wet seasons.
Damien Minenna, Frédéric André, Yves Elskens
et al.
The traveling-wave tube is a critical subsystem for satellite data transmission. Its role in the history of wireless communications and in the space conquest is significant, but largely ignored, even though the device remains widely used nowadays. This paper present, albeit non-exhaustively, circumstances and contexts that led to its invention, and its part in the worldwide (in particular in Europe) expansion of TV broadcasting via microwave radio-relays and satellites. We also discuss its actual contribution to space applications and its conception. The originality of this paper comes from the wide period covered (from first slow-wave structures in 1889 to present space projects) and from connection points made between this device and commercial exploitations. The appendix deals with an intuitive pedagogical description of the wave-particle interaction.
Cross-modality generation is an emerging topic that aims to synthesize data in one modality based on information in a different modality. In this paper, we consider a task of such: given an arbitrary audio speech and one lip image of arbitrary target identity, generate synthesized lip movements of the target identity saying the speech. To perform well in this task, it inevitably requires a model to not only consider the retention of target identity, photo-realistic of synthesized images, consistency and smoothness of lip images in a sequence, but more importantly, learn the correlations between audio speech and lip movements. To solve the collective problems, we explore the best modeling of the audio-visual correlations in building and training a lip-movement generator network. Specifically, we devise a method to fuse audio and image embeddings to generate multiple lip images at once and propose a novel correlation loss to synchronize lip changes and speech changes. Our final model utilizes a combination of four losses for a comprehensive consideration in generating lip movements; it is trained in an end-to-end fashion and is robust to lip shapes, view angles and different facial characteristics. Thoughtful experiments on three datasets ranging from lab-recorded to lips in-the-wild show that our model significantly outperforms other state-of-the-art methods extended to this task.
Mehmet Şükrü Kuran, Ahmet Erdem Tozoğlu, Cinzia Tavernari
In this paper we explain our experiences and observations on a blended world history course which combines classical lecture and discussion elements as well as video game sessions in which the students play strategy video games with heavy historical focus. The course, named Playing with The Past, is designed to experiment on how to integrate video games on teaching history especially in order to achieve a higher understanding of the contemporary social, political, economical, and technological context of a given era for a given nation. We ran the course four times between 2015 - 2018 with different video game titles having different historical models and observe the experiences and learning of students based on the quality of their written essays and articles. Our experiments and observations could be beneficial not only for the design of a general world history course, but also for a history course on specific periods, cultures, and nations.
El artículo aborda un acontecimiento histórico poco estudiado, pero muchas veces aludido. Para ello se intenta ofrecer, de manera preliminar, una síntesis interpretativa y una caracterización de la movilización opuesta al contrato-ley entre el Estado costarricense y la Aluminium Company of America (ALCOA), cuyo protagonista principal fue el componente estudiantil universitario. Tal investigación se hace mediante la descripción y el análisis del movimiento, indagando causas, composición, formas de acción, discursividades y consecuencias. Además, se analizan las principales respuestas dadas -mediante acciones y discursividades- por parte de contendientes nacionales del movimiento: los entes gubernamentales y los medios de comunicación.
Rapid, targeted hand movements exhibit a regular movement pattern described by Fitts law. We develop a model of these movements in which this movement pattern results from an optimal control model describing rapid hand movements and a utility model describing the speed/accuracy trade-off between moving the hand rapidly to the target and hitting the target accurately. The optimal control model is constructed using principled approach in which we forbid the muscle forces to exhibit any discontinuities and require the cost to be expressed in terms of a psychophysical representation of the movement. This yields a yank-control or jerk-control model of the movement which exhibits two constants of the motion that are closely related to the energy and momentum in classical mechanics. We force the optimal control model to obey Fitts law by requiring a particular relationship hold between the constants of the motion and the size of the target and show that the resulting model compares well to a standard expression of Fitts law obtained empirically using observations of computer mouse movements. We then proceed to further show how this relationship may be obtained as the result of a simple models of the movement accuracy and the speed/accuracy trade-off. We use the movement accuracy model to analyze observed differences in computer mouse movement patterns between older adults with mild cognitive impairment and intact older adults. We conclude by looking at how a subject might carry out in practice the optimization implicit in resolving the speed/accuracy trade-off in our model.
El artículo explica las causas socioambientales que en la primera mitad del siglo XX presionaron la emigración de familias del pueblo huetar, tanto a lo interno del actual cantón de Mora, Costa Rica, como hacia fuera de este mismo. En este estudio se establecen, además, las relaciones entre las causas de dichos desplazamientos y la participación periférica de Costa Rica en la economía-mundo entre 1900 y 1955.
Guatemala: Las líneas de su mano, es un texto especialmente sugerente para explorar las diferentes perspectivas desde las que los grupos ladinos han construido el mundo indígena guatemalteco, referente fundamental en la invención de su propia identidad. Sostenemos que, en el ansiado reencuentro con su tierra conforme el narrador penetra en la subjetividad del otro, su mirada termina por volcarse hacia él mismo, para hurgar en esos lugares sinuosos de la subjetividad, perturbadores sitios donde, quien representa lo que no se desea ser, se convierte en espejo de sí. La argumentación contenida en estas páginas se fundamenta en la interpelación de diferentes tradiciones intelectuales, las cuales se constituyeron en herramientas para ingresar en el análisis hermenéutico del texto.
Ferdinando Arzarello, Livia Giacardi, Fulvia Furinghetti
et al.
The celebration of the Centennial of the International Commission on Mathematical Instruction offered the occasion to look back at the history of ICMI and outline the evolution of mathematics education until it achieved its present status as an academic discipline. The years after WWII up to the late 1960s were crucial in this evolution for both the settlement of some institutional aspects, mainly concerning the relationship with mathematicians, and the establishment of new trends of the activities. In this paper we outline, on the basis of unpublished documents, the role of two important figures in those years: Heinrich Behnke and Hans Freudenthal.
Lars Lau Raket, Britta Grimme, Gregor Schöner
et al.
A central task in the analysis of human movement behavior is to determine systematic patterns and differences across experimental conditions, participants and repetitions. This is possible because human movement is highly regular, being constrained by invariance principles. Movement timing and movement path, in particular, are linked through scaling laws. Separating variations of movement timing from the spatial variations of movements is a well-known challenge that is addressed in current approaches only through forms of preprocessing that bias analysis. Here we propose a novel nonlinear mixed-effects model for analyzing temporally continuous signals that contain systematic effects in both timing and path. Identifiability issues of path relative to timing are overcome by using maximum likelihood estimation in which the most likely separation of space and time is chosen given the variation found in data. The model is applied to analyze experimental data of human arm movements in which participants move a hand-held object to a target location while avoiding an obstacle. The model is used to classify movement data according to participant. Comparison to alternative approaches establishes nonlinear mixed-effects models as viable alternatives to conventional analysis frameworks. The model is then combined with a novel factor-analysis model that estimates the low-dimensional subspace within which movements vary when the task demands vary. Our framework enables us to visualize different dimensions of movement variation and to test hypotheses about the effect of obstacle placement and height on the movement path. We demonstrate that the approach can be used to uncover new properties of human movement.