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The coda draws out the implications of modernist physiognomy for our contemporary moment. As we move from nineteenth-century physiognomy to modernist physiognomy, we encounter more minimalist descriptions of faces – facial sketches, outlines. We encounter faces reduced to a minimalist form. This form is taken up by contemporary facial recognition technologies. Across the scholarly literature on facial recognition technologies, there is a growing awareness of bias: technology is biased because training sets are biased. As Cathy O’Neil writes, “data embeds the dark past.” At the conclusion of this book, the coda frames its contribution to the call issued by Soshana Zuboff in Surveillance Capitalism: “If the digital future is to be our home, then it is we who must make it so.” This book will have aimed to give historicized substance to a fragment of this past: algorithmic data embeds the long history of the face, including elements of modernist physiognomy.
This chapter follows on from the previous chapter in quantum statistical mechanics but specialising on systems with identical particles. Using Gibbs prescritpion on generic states from Chapter 3, the occupation number representation is introduced. Constraints imposed on statistics by irreducible representations of the permutation group are discussed. These group-theoretic considerations are used to justify the use of Gentile’s parastatistics. Fermions and bosons are introduced as special cases of Gentile’s statistics, corresponding to the trivial representation of the permutation group for bosons, and the sign representation of the permutation group for fermions. Basic applications to fermions and bosons is given, including the Fermi–Dirac and Bose–Einstein statistics. A detailed expose of why photons are said to have zero chemical potential is also proposed.
This chapter provides a framework for the reader to describe abnormalities of the electrographic background and foreground. The electrographic background may be described based on symmetry, continuity, voltage, organization, reactivity, and sleep architecture. A waveform or potential abnormality may be described based on its location, occurrence (sporadic or repetitive – rhythmic or periodic), and morphology (slow or sharp wave). Further, this description can be qualified based on modifiers such as prevalence, frequency, duration, and amplitude. When reporting waveforms, the modifiers should precede the key features in your description. [88 words/557 characters]
One of life’s most fundamental revelations is change. Presenting the fascinating view that pattern is the manifestation of change, this unique book explores the science, mathematics, and philosophy of change and the ways in which they have come to inform our understanding of the world. Through discussions on chance and determinism, symmetry and invariance, information and entropy, quantum theory and paradox, the authors trace the history of science and bridge the gaps between mathematical, physical, and philosophical perspectives. Change as a foundational concept is deeply rooted in ancient Chinese thought, and this perspective is integrated into the narrative throughout, providing philosophical counterpoints to customary Western thought. Ultimately, this is a book about ideas. Intended for a wide audience, not so much as a book of answers, but rather an introduction to new ways of viewing the world.
Symmetries are a key idea in physics. In the classical world, they are associated to conservation laws, courtesy of Emmy Noether. The same, and more, is true in the quantum world. In this chapter we explore how symmetries manifest themselves in quantum mechanics. Special attention will be given to time evolution and the role of SU(2) and angular momentum
This accessible text is an introduction to the theory of phase transitions and its application to real materials. Assuming some familiarity with thermodynamics and statistical mechanics, the book begins with a primer on the thermodynamics of equilibrium phase transitions, including the mean-field and Ginzburg-Landau approaches. The general kinetic features and dynamics of phase transitions are explained, ensuring that readers are familiar with the key physical concepts. With the foundations established, the general theory is applied to the study of phase transitions in a wide range of materials including ferroic materials, caloric materials, liquid crystals and glasses. Non-equilibrium phase transitions, superconductors and quantum phase transitions are also covered. Including exercises throughout and solutions available online, this text is suitable for graduate courses as well as researchers in physics and materials science seeking a primer on popular and emerging research topics.
This appendix gives some examples of presentations of 2-categories by 3-polygraphs. In many examples, the presented 2-categories are in fact monoidal categories and, actually, PROs.
The principle of equality of belligerents mandates that the rules of international humanitarian law (IHL) apply equally to each party in an armed conflict, regardless of the legality of their use of force under jus ad bellum. This principle has been extensively analyzed in academic literature; its importance is universally recognized and its legal foundations and effects are well defined. However, this is primarily true with respect to its application in international armed conflicts (IACs) – in contrast, the principle does not receive equivalent recognition in situations of non-international armed conflict (NIAC), where at least one party is a non-State armed group. The issue arises from the lack of an accepted definition of the principle in NIACs, given the absence of any applicable international jus ad bellum in such conflicts. The present paper will try to remedy this issue by proposing that the principle is composed of two elements: symmetry of application and symmetry of substance. It will introduce this definition as it applies to IACs and NIACs and argue that the principle in NIACs is primarily defined by its symmetry of substance component. It will also evaluate the principle’s nature as a general principle of IHL and explore some of its concrete effects on IHL rules.
This Element is broadly about the geometrization of physics, but mostly it is about gauge theories. Gauge theories lie at the heart of modern physics: in particular, they constitute the Standard Model of particle physics. At its simplest, the idea of gauge is that nature is best described using a descriptively redundant language; the different descriptions are said to be related by a gauge symmetry. The over-arching question this Element aims to answer is: why is descriptive redundancy fruitful for physics? I will provide three inter-related answers to the question: ``Why gauge theory?'', that is: why introduce redundancies in our models of nature in the first place? The first is pragmatic, or methodological; the second is based on geometrical considerations, and the third is broadly relational.
Some anatomical structures vary greatly in number among species, a phenomenon that often remains unexplained. We investigate interspecific variation in the number of collar spines among trematodes from the superfamily Echinostomatoidea, using a dataset comprising hundreds of species. These trematodes possess a ring of spines around their anterior sucker; in some families, they form 2 arcs on either side of the sucker, with a central gap, whereas in other families, they form a continuous collar with no gap. First, we confirm that even numbers of spines are the norm among species in which they are arranged as 2 arcs with a central gap, while odd numbers (mainly prime numbers) predominate among species in which spines form a continuous collar. Second, we tested whether variation among species in the number of spines might reflect selective pressures. The spines serve to attach the worm to the inside lining of the host gut. Our analysis confirms that spine numbers correlate positively with worm body size among echinostomes, supporting the hypothesis that larger worms require more spines for stronger attachment. Finally, we tested whether phylogenetic conservatism may explain interspecific variation in the number of collar spines, i.e. whether closely related species have more similar numbers of spines than expected by chance due to shared ancestry. Our analysis confirms that spine numbers show strong phylogenetic conservatism across species. Overall, our findings indicate that the number of collar spines, a hallmark of echinostomes, is the product of conserved phylogenetic inheritance overlaid by adaptive functional adjustments.
The main aim of Chapter 2 is to develop your understanding of how signs are formed and to help you improve the accuracy of your sign articulation. Section 2.1 contains detailed information related to the five components of signs: handshape, location, movement, orientation and non-manual features, and also includes some description of the arrangement of the hands and how to put signs together with the least influence from English possible. The following section, 2.2, provides examples of common sign articulation errors made in relation to the five components and how to correct them. This includes explanation of the typical errors that are made when learners rely on English words and do not think about the meaning or context of the concept they want to express. This chapter ends with Section 2.3, which provides exercises to improve sign articulation and encourages BSL learners to practice use of both manual and non-manual features of BSL.
Three-dimensional contingency tables are analyzed, with one variable (e.g., sex) as a factor, and with a natural relation between the other variables (e.g. left and right eye vision). Models of special interest, like symmetry and proportional symmetry between the related variables, and homogeneity across the factor levels, are investigated. Maximum likelihood estimators of parameters and partitions of chi-square goodness-of-fit statistics are explicitly presented; the independence of certain models is noted, and an example is discussed.
Symmetry is a salient visual feature in the natural world, yet the perception of symmetry may be influenced by how natural lighting conditions (e.g., shading) fall on the object relative to its symmetry axis. Here, we investigate how symmetry detection may interact with luminance polarity grouping, and whether this modulates neural responses to symmetry, as evidenced by the Sustained Posterior Negativity (SPN) component of Event-Related Potentials (ERPs). Stimuli were dot patterns arranged either symmetrically (reflection, rotation, translation) or quasi-randomly, and by luminance polarity about a grouping axis (i.e., black dots on one side and white dots on the other). We varied the relative angular separation between the symmetry and polarity-grouping axes: 0, 30, 60, 90 deg. Participants performed a two interval-forced-choice (2IFC) task indicating which interval contained the symmetrical pattern. We found that accuracy for the 0 deg polarity-grouped condition was higher compared to the single-polarity condition for rotation and translation (but not reflection symmetry), and higher than all other angular difference (30, 60, 90) conditions for all symmetry types. The SPN was found to be separated topographically into an early and late component, with the early SPN being sensitive to luminance polarity grouping at parietal-occipital electrodes, and the late SPN sensitive to symmetry over central electrodes. The increase in relative angular differences between luminance polarity and symmetry axes highlighted changes between cardinal (0, 90 deg) and other (30, 60 deg) angles. Critically, we found a polarity-grouping effect in the SPN time window for noise only patterns, which was related to symmetry type, suggesting a task/ symmetry pattern influence on SPN processes. We conclude that luminance polarity grouping can facilitate symmetry perception when symmetry is not readily salient, as evidenced by polarity sensitivity of early SPN, yet it can also inhibit neural and behavioral responses when luminance polarity and symmetry axes are not aligned.
Helices are one of the most frequently encountered symmetries in biological assemblies. Helical symmetry has been exploited in electron microscopic studies as a limited number of filament images, in principle, can provide all the information needed to do a three-dimensional reconstruction of a polymer. Over the past 25 years, three-dimensional reconstructions of helical polymers from cryo-EM images have shifted completely from Fourier–Bessel methods to single-particle approaches. The single-particle approaches have allowed people to surmount the problem that very few biological polymers are crystalline in order, and despite the flexibility and heterogeneity present in most of these polymers, reaching a resolution where accurate atomic models can be built has now become the standard. While determining the correct helical symmetry may be very simple for something like F-actin, for many other polymers, particularly those formed from small peptides, it can be much more challenging. This review discusses why symmetry determination can be problematic, and why trial-and-error methods are still the best approach. Studies of many macromolecular assemblies, such as icosahedral capsids, have usually found that not imposing symmetry leads to a great reduction in resolution while at the same time revealing possibly interesting asymmetric features. We show that for certain helical assemblies asymmetric reconstructions can sometimes lead to greatly improved resolution. Further, in the case of supercoiled flagellar filaments from bacteria and archaea, we show that the imposition of helical symmetry can not only be wrong, but is not necessary, and obscures the mechanisms whereby these filaments supercoil.
This chapter advocates an ethic of “symmetric interpretation” as a solution to the challenges outlined in Chapter 1. To prevent undue politicization of constitutional law, judges should favor, when possible, constitutional understandings that are “symmetric” in the sense of conferring valuable protections across both sides of the nation’s major political and ideological divides. By the same token, they should disfavor understandings that frame constitutional law as a matter of zero-sum competition between rival partisan visions. Favoring symmetric understandings in this sense will not always be possible. When it is possible, however, favoring symmetry may provide a point of common orientation for judges with differing policy preferences and interpretive outlooks. Reflecting this approach's inherent appeal, an inchoate preference for symmetry is already evident in judges’ opinions, oral argument questions, and reasoning.
This chapter advances theoretical reasons to support symmetric interpretation. First, favoring symmetry accords with the Constitution’s character as a comparatively terse, “framework” document focused on establishing democratic procedures rather than definitive policies. Second, an ethic of symmetric interpretation accords with widely accepted features of judicial role-morality. Finally, symmetric interpretation accords with the framers’ own constitutional aspirations and interpretive methods. Multiple widely accepted theoretical considerations in constitutional law thus support preferring symmetric understandings when possible.
Originally established by “we the people,” as its preamble majestically states, the Constitution belongs to us all. But Americans increasingly treat it as the property of one political faction or the other. In keeping with their own preferences, conservatives interpret the Constitution to protect religion, limit gun control, and obstruct administrative governance while allowing state-level regulation of moral questions like abortion. Progressives see a mirror-image constitution that advances social justice, confers broad federal power, and allows flexible administrative regulation while at the same time limiting state and local police authority and guaranteeing sexual and reproductive autonomy. As national politics have grown ever more divided and polarized, preventing either side from implementing its goals through federal legislation, both coalitions have dreamed of capturing the courts and implementing their vision instead through constitutional interpretation. A document that should be a source of unity and shared commitments has become a vehicle for extending political conflict.
The third edition of this successful textbook has been redesigned to reflect the progress of the field in the last decade, including the latest studies of the Higgs boson, quark–gluon plasma, progress in flavour and neutrino physics and the discovery of gravitational waves. It provides undergraduate students with complete coverage of the basic elements of the Standard Model of particle physics, assuming only introductory courses in nuclear physics, special relativity and quantum mechanics. Examples of fundamental experiments are highlighted before discussions of the theory, giving students an appreciation of how experiment and theory interplay in the development of physics. The author examines leptons, hadrons and quarks, before presenting the dynamics and the surprising properties of the charges of the different forces, concluding with a discussion on neutrino properties beyond the Standard Model. This title is also available as open access on Higher Education from Cambridge University Press.
In modern physics, symmetries are a powerful tool to constrain the form of equations, namely the Lagrangian that describes the system. Equations are assumed to be invariant under the transformation of a given group, which may be discrete or a continuous Lie group. Classification of the various types of symmetry. The concept of spontaneous symmetry breaking. It will evolve into the Higgs mechanism, which gives origin to the masses of the vector bosons that mediate the weak interactions, of the quarks and of the charged leptons.
The discrete symmetries, in particular the parity and the particle–antiparticle conjugation operations and the corresponding quantum numbers.
An important dynamical symmetry of the hadrons, the invariance of the Lagrangian under rigid rotations in an ‘internal’ space, the isospin space. The unitary group is SU(2).