In recent years, inverse spectra were investigated with imaging optics and a quantitative description with radiometric units was suggested. It could be shown that inverse spectra complement each other additively to a constant intensity level. Since optical intensity in radiometric units is a power area density, it can be expected that energy densities of inverse spectra also fulfill an inversion equation and complement each other. In this contribution we report findings on a measurement of the power area (...) class='Hi'>density of inverse spectra for the near ultraviolet, visible and the infrared spectral range. They show the existence of corresponding spectral regions ultra-yellow and infra-cyan in the inverted spectrum and thereby present additional experimental evidence for equivalence of inverse spectra beyond the visible range. (shrink)

Principles of Laser Spectroscopy and Quantum Optics is an essential textbook for graduate students studying the interaction of optical fields with atoms. It also serves as an ideal reference text for researchers working in the fields of laser spectroscopy and quantum optics. The book provides a rigorous introduction to the prototypical problems of radiation fields interacting with two- and three-level atomic systems. It examines the interaction of radiation with both atomic vapors and condensed matter systems, the density matrix (...) and the Bloch vector, and applications involving linear absorption and saturation spectroscopy. Other topics include hole burning, dark states, slow light, and coherent transient spectroscopy, as well as atom optics and atom interferometry. In the second half of the text, the authors consider applications in which the radiation field is quantized. Topics include spontaneous decay, optical pumping, sub-Doppler laser cooling, the Heisenberg equations of motion for atomic and field operators, and light scattering by atoms in both weak and strong external fields. The concluding chapter offers methods for creating entangled and spin-squeezed states of matter. Instructors can create a one-semester course based on this book by combining the introductory chapters with a selection of the more advanced material. A solutions manual is available to teachers. Rigorous introduction to the interaction of optical fields with atoms Applications include linear and nonlinear spectroscopy, dark states, and slow light Extensive chapter on atom optics and atom interferometry Conclusion explores entangled and spin-squeezed states of matter Solutions manual. (shrink)

The concept of a technical frontier in branches of experimental measurement, such as the resolution of the microscope, angular measure and time telling, has been around for more than 60 years. The purpose of this brief paper is to identify the technical frontier operating on the achromatic astronomical telescope, where a limiting factor of the resolution of fine detail was the quality of the optical glass available. The achromatically corrected objective is formed from two kinds of glass, the common (...) crown glass and the heavy clear flint glass or lead glass. This last was difficult to make homogeneous, that is without regions of different density, and therefore different refraction and dispersion. Unusually, optical glass had to pass a second frontier, this time placed on the whole glass industry by the English Government in the form of excise duty, administered with a bureaucratic efficiency that effectively stopped, in around 1800, the making of optical glass suitable for the serious astronomical telescopes. The result of the tax imposition was to delay the English production of improved optical glass for more than 80 years. (shrink)

Johannes Kepler dedicated much of his work to discover a law for the refraction of light. Unfortunately, he formulated an incorrect law. Nevertheless, it was useful for anticipating the behavior of light in some specific conditions. Some believe that Kepler did not have the elements to formulate the law that was later accepted by the scientific community, that is, the Snell–Descartes law. However, in this paper, we propose a model that agrees with Kepler’s heuristics and that is also successful in (...) anticipating the behavior of light when it passes through a surface that separates two media with different optical densities. This model adopts strategies that were recommended by Kepler in two types of analogies. The obstacles that led to the failure of the two types of analogies are presented in the article, and we argue that the model proposed here could overcome these specific obstacles. Finally, we show how the proposed model could be articulated with Kepler’s metaphysics of light. (shrink)

The effect of germanium addition on the physical properties, i.e. density, molar volume, compactness, number of lone-pair electrons, average coordination number, heat of atomization, mean bond energy, cohesive energy and glass-transition temperature, of (Se80Te20)100− x Ge x (x = 0, 2, 4, 6) bulk glassy alloys was investigated. The density of the glassy alloys is found to decrease with increasing Ge content. The molar volume and compactness of the structure of the glass were determined from the measured (...) class='Hi'>density. The mean bond energy is proportional to the glass-transition temperature. The cohesive energy of the samples has been calculated using a chemical bond approach and is correlated with an increase in the optical energy gap with increase in the Ge content. The heat of atomization was also calculated and correlated with the optical energy gap. The glass-transition temperature has been estimated using different methods and is found to increase with an increase of Ge content. (shrink)

Background: Primary open-angle glaucoma patients exhibit widespread white matter degeneration throughout their visual pathways. Whether this degeneration starts at the pre- or post-geniculate pathways remains unclear. In this longitudinal study, we assess the progression of WM degeneration exhibited by the pre-geniculate optic tracts and the post-geniculate optic radiations of POAG patients over time, aiming to determine the source and pattern of spread of this degeneration.Methods: Diffusion-weighted MRI scans were acquired for 12 POAG patients and 14 controls at two time-points 5.4 (...) ± 2.1 years apart. Fiber density, an estimate of WM axonal density, was computed for the OTs and ORs of all participants in an unbiased longitudinal population template space. First, FD was compared between POAG patients and the controls at time-point 1 and time-point 2 independently. Secondly, repeated measures analysis was performed for FD change in POAG patients between the two time-points. Finally, we compared the rate of FD change over time between the two groups.Results: Compared to the controls, POAG patients exhibited significantly lower FD in the left OT at TP1 and in both OTs and the left OR at TP2. POAG patients showed a significant loss of FD between the time-points in the right OT and both ORs, while the left OR showed a significantly higher rate of FD loss in POAG patients compared to the controls.Conclusions: We find longitudinal progression of neurodegenerative WM changes in both the pre- and post-geniculate visual pathways of POAG patients. The pattern of changes suggests that glaucomatous WM degeneration starts at the pre-geniculate pathways and then spreads to the post-geniculate pathways. Furthermore, we find evidence that the trans-synaptic spread of glaucomatous degeneration to the post-geniculate pathways is a prolonged process which continues in the absence of detectable pre-geniculate degenerative progression. This suggests the presence of a time window for salvaging intact post-geniculate pathways, which could prove to be a viable therapeutic target in the future. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:The Listening Eye: Postmodernism, Paranoia, and the HypervisibleJerry Aline Flieger (bio)Jean Baudrillard. The Transparency of Evil: Essays on Extreme Phenomena. Trans. James Benedict. London: Verso, 1993. Trans. of La transparence du mal: Essai sur les phénomènes extrêmes. Paris: Galilée, 1990.Jean-François Lyotard. The Inhuman: Reflections on Time. Trans. Geoff Bennington and Rachel Bowlby. Stanford: Stanford UP, 1991. Trans. of L’inhumain. Paris: Galilée, 1988.Slavoj Zizek. Looking Awry: An Introduction to Jacques (...) Lacan Through Popular Culture. Cambridge: MIT P, 1992.“To the insides of the ear belong those who have a sight of internal hearing.” That’s the nocturnal look, the listening eye.—Emmanuel Swedenborg, cited in Lyotard, The InhumanPostmodernism, Yet AgainIn this essay, I shall take a cue from Slavoj Zizek’s discussion of Lacanian anamorphosis, or skewed perspective (Looking Awry), in order to read three dissimilar works alongside one another, and from a “paranoid” slant. For in spite of sometimes radically incommensurate subject matter, the three works I discuss here—The Transparency of Evil (Jean Baudrillard), Looking Awry (Slavoj Zizek) and The Inhuman (Jean-François Lyotard)—all share a focus on the dehumanizing effects of technology as determinants of what Lyotard has called the postmodern condition. 1 Moreover, all three works themselves adopt something like a paranoid perspective, suggesting that under the sway of an ethic of sheer performativity, human contact—face to face—has been rendered obsolete by interface.In the bleak vision of The Transparency of Evil (1993), for instance, Baudrillard describes an isolated disembodied satellite man, cut loose from his moorings: “The centrifugal force of our proliferating technologies has stripped us of all weight.... Freed of all density, all gravity, we are being dragged into an orbital motion which threatens to become perpetual” [30–31]. Similarly, in “The Ecstasy of Communication” (1983), Baudrillard describes a robotic subject mesmerized by pornographic hypervisibility, [End Page 90] “more visible than the visible... the obscenity of what no longer has any secret, or what dissolves completely in information and communication” [130–31]. 2Like Baudrillard, Lyotard (The Inhuman) describes the loss of dimensional intersubjectivity, suggesting that space is no longer an enabling interval between subjects, the scene of the exchanged gaze: contemporary cyberspace is the scene of communication without community, saturated with hypervisible information. But while for Baudrillard, we are already in weightless orbit, in a postcatastrophic, fractal aftermath, for Lyotard our fate is not yet cast, although adumbrated disaster—the end of the species or of the universe—provides a telos for our existence.Slavoj Zizek is not nearly so metaphysical, nor so glum, as his fellow post-philosophers, but he is every bit as concerned with the optical, Looking Awry. Zizek is a patient and even cheery exegete of Lacan, attempting to “introduce” Lacanian thought by looking at film, detective fiction, and other user-friendly instances of modern culture as templates of theory. Indeed, compared to his fellow travelers, Zizek is resolutely quotidian, even earthbound, focusing on the contemporary human subject as consumer/spectator, seated not in a satellite capsule or at a computer terminal but at the movies, popcorn in hand.Yet in spite of his goodwill, Zizek’s take on postmodernism is anything but sanguine: he too depicts a subject who is prey to the fascination of overexposed “obscene” virtual reality (X-rated Hitchcock, if you will), and always threatened as well by the eruption of the menacing Lacanian real into the web of symbolic reality—an intrusion that awakens the paranoid “post-man” from an absorption in the image on the screen, with a reminder of the precariousness of all that appears evident or meaningful. Thus in “The Obscene Object of Postmodernity” [Looking Awry, chap. 8], Zizek describes a blot or stain that sticks out or refuses assimilation to the totalizing gaze, eclipsing the heretofore meaningful and legible symbolic universe with an ineffable real that “produces a radical opacity and blocks every essay of interpretation” [151]. I suggest that Zizek’s notion of the obscene object as blot—like the hair on the camera lens that “disturbs” our absorption in the screen—as well as Lyotard’s notion of obdurate matter, may... (shrink)

The Royal Society possesses three long-focus simple lenses of diameters 195, 210 and 230 mm, all inscribed with the signature ‘C. Huygens’ and various dates in the year 1686. These prove to have been made by Constantine Huygens, the elder brother of the famous Christiaan Huygens. All three lenses have been examined by a variety of physical and chemical methods, both to define their optical characteristics and to establish the composition of dated samples of late-seventeenth-century Continental glass. The focal (...) lengths of 37·9, 50·1 and 65·2 metres found by combination agree with Huygens' own values of 122, 170 and 210 feet respectively, and are so great that practical employment of the lenses in aerial telescopes has rarely been achieved. All are made from the same very poor glass—a heterogeneous and discoloured potash-rich ‘forest glass’—with a refractive index of 1·516, a costringence of 60, and a density of 2·5 g cm−3. The three lenses were ground with just two concave laps, of radii of curvature 27·11 and 71·15 metres, one lens being plano-convex to a high degree of accuracy. A claim by previous investigators that one lens was a ‘light flint’ glass has been disproved. (shrink)

Gibson's ecological approach to depiction is compared with Nelson Goodman's relativist theory of representation. Goodman's commitment to radical relativism and Gibson's to direct realism would make these thinkers unlikely candidates for comparison if Goodman himself had not indicated a substantial body of agreement with Gibson in the area of picture perception. The present study analyzes this agreement through systematic discussion of the following theses: realism in representation is not a function of geometrical optics, physical similarity to what is depicted, or (...) deception; pictures differ in density and articulation from words, so that picturing has no explicit vocabulary; and artists can teach us new ways to see the world. The agreement between Goodman and Gibson has wide-ranging implications for the further development of what might be called a Gibsonian relativism. (shrink)

In quantum field theory, coherent states can be created that have negative energy density, meaning it is below that of empty space, the free quantum vacuum. If no restrictions existed regarding the concentration and permanence of negative energy regions, it might, for example, be possible to produce exotic phenomena such as Lorentzian traversable wormholes, warp drives, time machines, violations of the second law of thermodynamics, and naked singularities. Quantum Inequalities have been proposed that restrict the size and duration of (...) the regions of negative quantum vacuum energy that can be accessed by observers. However, QIs generally are derived for situations in cosmology and are very difficult to test. Direct measurement of vacuum energy is difficult and to date no QI has been tested experimentally. We test a proposed QI for squeezed light by a meta-analysis of published data obtained from experiments with optical parametric amplifiers and balanced homodyne detection. Over the last three decades, researchers in quantum optics have been trying to maximize the squeezing of the quantum vacuum and have succeeded in reducing the variance in the quantum vacuum fluctuations to \ dB. To apply the QI, a time sampling function is required. In our meta-analysis different time sampling functions for the QI were examined, but in all physically reasonable cases the QI is violated by much or all of the measured data. This brings into question the basis for QI. Possible explanations are given for this surprising result. (shrink)

A simple line drawing can reproduce a vast collection of phenomenal discontinuities: optical, material, chromatic, and also of density, dimension, resistance. All these discontinuities correspond to physical realities quite different from each other. This fact leads us to consider that our brain can retrieve from a pencil stroke a broad and amazing lot information at several levels, from the physical to the phenomenological, from the logical to the cognitive. Drawing demonstrates the existence in our brain of a complex (...) communication web between the visual and action cortical areas and the zones of the paleo encephalon, indicating the biological necessity of establishing a continuity between vision and action, between representation and abstraction. Thus, drawing is a natural language, and represents a biological and expressive invariant; it is also a cultural language, the result of technical and symbolic development of a civilization; and it is, finally, an universal language, indeed the main communication system between different cultures. (shrink)

Handwritten text recognition is considered as the most challenging task for the research community due to slight change in different characters’ shape in handwritten documents. The unavailability of a standard dataset makes it vaguer in nature for the researchers to work on. To address these problems, this paper presents an optical character recognition system for the recognition of offline Pashto characters. The problem of the unavailability of a standard handwritten Pashto characters database is addressed by developing a medium-sized database (...) of offline Pashto characters. This database consists of 11352 character images. Enriched feature extraction techniques of histogram of oriented gradients and zoning-based density features are used for feature extraction of carved Pashto characters. K-nearest neighbors is considered as a classification tool for the proposed algorithm based on the proposed feature sets. A resultant accuracy of 80.34% is calculated for the histogram of oriented gradients, while for zoning-based density features, 76.42% is achieved using 10-fold cross validation. (shrink)

At the beginning of the seventeenth century, the sine law of refraction had been discovered. Thus, natural philosophers tried even more to find a cause of refraction and to demonstrate the law. One of them was Thomas Hobbes, who was the author of the Leviathan and also worked on optics. At first, in the Hobbes analogy , he was influenced by Ibn al-Haytham, just as Descartes was in his famous proof in the Dioptrique . In his later optical scripts (...) Tractatus Opticus I , Tractatus Opticus II , and A Minute or First Draught of the Optiques , he developed a new explanation. Rejecting a corpuscular theory of light, Hobbes conceived a ray not as a body but as a motion originating from the light source: a ray can only be the motion of a body. The normal to the sides of a ray is called 'linea lucis'. If a ray is incident into another medium with a different density, one part of the linea lucis will be in the rarer and the other in the denser medium during an imperceptibly short period. Because the resistances in the two media are different, the parts of the linea lucis will move with different velocities; as a result the linea lucis will rotate and the direction of the ray will be changed. The next explanation given in De Corpore comes closer to the first one that Hobbes set down in the analogy. It must be asked why he replaced the theory of rotation by one which seems to carry less conviction. The reason could be that the dropped theory is founded in part on basic requirements of a corpuscular theory of light. Abandoning the whole theory might have been the lesser evil for Hobbes. In two later works, the Problemata Physica and the Decameron Physiologicum , Hobbes varied his explanation without giving any proof for the sine law. It should be noted, however, that in the Decameron he refers to the proof contained in the Tractatus Opticus I, but not that given in De Corpore. (shrink)

It is shown that below the threshold of pair creation, a consistent quantum mechanical interpretation of relativistic spin-0 and spin-1 particles (both massive and mussless) ispossible based an the Hamiltonian-Schrödinger form of the firstorder Kemmer equation together with a first-class constraint. The crucial element is the identification of a conserved four-vector current associated with the equation of motion, whose time component is proportional to the energy density which is constrainedto be positive definite for allsolutions. Consequently, the antiparticles must be (...) interpreted as positive-energy states traveling backward in time. This also makes it possible to define hermitian position operators with localized eigensolutions (δ-functions) as well as Bohmian trajectories for bosons. The exact theory is obtained by “second quantization” and is mathematically completely equivalent to conventional quantum field theory. The classical field emerges in the high mean number limit of coherent states of the exact theory. The formalism provides a new basis for computing tunneling times for photons and chaotic phenomena in optics. (shrink)

In his ‘Theory of Light and Colours’, presented to the Royal Society in November 1801, Thomas Young defended a mechanical explanation of the coloured fringes observed outside of the shadow of an opaque object – the so-called ‘colours by inflection’ – that was based on the hypothesis of an ethereal density gradient surrounding all material bodies. However, two years later, he publicly rejected that hypothesis, without giving much detail of his reasons. Although Geoffrey Cantor has demonstrated the crucial role (...) of mechanical and astronomical arguments in explaining the withdrawal of this fundamental hypothesis long ago, the purpose of this article is to draw deeper attention to a set of experiments performed by David Brewster on the inflection of light, described in a letter he addressed to the Royal Society in January 1802, but was retained by William Herschel, and finally was neither read before the Society, nor published in its Philosophical Transactions. For the hypothesis that will be evaluated here is that these unpublished experiments of Brewster’s were eventually known to Young through the mediation of Herschel, and eventually played a significant role in Young’s rejection of his ether distribution hypothesis. (shrink)

If the density matrix is treated as an objective description of individual systems, it may become possible to attribute the same objective significance to statistical mechanical properties, such as entropy or temperature, as to properties such as mass or energy. It is shown that the de Broglie--Bohm interpretation of quantum theory can be consistently applied to density matrices as a description of individual systems. The resultant trajectories are examined for the case of the delayed choice interferometer, for which (...) Bell [Int. J. Quantum chem. 155--159, (1980)] appears to suggest that such an interpretation is not possible. Bell’s argument is shown to be based upon a different understanding of the density matrix to that proposed here. (shrink)

The following strong form of density of definable types is introduced for theoriesTadmitting a fibered dimension functiond: given a modelMofTand a definable setX⊆Mn, there is a definable typepinX, definable over a code forXand of the samed-dimension asX. Both o-minimal theories and the theory of closed ordered differential fields are shown to have this property. As an application, we derive a new proof of elimination of imaginaries for CODF.

Seventeenth-century optics naturalizes the eye while estranging the mind from objects. A mere screen, on which rests a blurry array of light stains, the eye no longer furnishes the observer with genuine re-presentations of visible objects. The intellect is thus compelled to decipher flat images of no inherent epistemic value, accidental effects of a purely causal process, as vague, reversed reflections of wholly independent objects. Reflecting on and trespassing the boundaries between natural and artificial, orderly and disorderly, this optical (...) paradox is a Baroque phenomenon; and it is the origin of Descartes’ celebrated doubt---whether we know anything at all. (shrink)

It is well known that density matrices can be used in quantum mechanics to represent the information available to an observer about either a system with a random wave function (“statistical mixture”) or a system that is entangled with another system (“reduced density matrix”). We point out another role, previously unnoticed in the literature, that a density matrix can play: it can be the “conditional density matrix,” conditional on the configuration of the environment. A precise definition (...) can be given in the context of Bohmian mechanics, whereas orthodox quantum mechanics is too vague to allow a sharp definition, except perhaps in special cases. In contrast to statistical and reduced density matrices, forming the conditional density matrix involves no averaging. In Bohmian mechanics with spin, the conditional density matrix replaces the notion of conditional wave function, as the object with the same dynamical significance as the wave function of a Bohmian system. (shrink)

Minkowski geometry is axiomatized in terms of the asymmetric binary relation of optical connectibility, using ten first-order axioms and the second-order continuity axiom. An axiom system in terms of the symmetric binary optical connection relation is also presented. The present development is much simpler than the corresponding work of Robb, upon which it is modeled.

In this paper we prove that the preordering $\lesssim $ of provable implication over any recursively enumerable theory $T$ containing a modicum of arithmetic is uniformly dense. This means that we can find a recursive extensional density function $F$ for $\lesssim $. A recursive function $F$ is a density function if it computes, for $A$ and $B$ with $A\lnsim B$, an element $C$ such that $A\lnsim C\lnsim B$. The function is extensional if it preserves $T$-provable equivalence. Secondly, we (...) prove a general result that implies that, for extensions of elementary arithmetic, the ordering $\lesssim $ restricted to $\Sigma_{n}$-sentences is uniformly dense. In the last section we provide historical notes and background material. (shrink)

In noun phrase coordinate constructions, there is a strong tendency for the syntactic structure of the second conjunct to match that of the first; the second conjunct in such constructions is therefore low in syntactic information. The theory of uniform information density predicts that low-information syntactic constructions will be counterbalanced by high information in other aspects of that part of the sentence, and high-information constructions will be counterbalanced by other low-information components. Three predictions follow: lexical probabilities will be lower (...) in second conjuncts than first conjuncts; lexical probabilities will be lower in matching second conjuncts than nonmatching ones; and syntactic repetition should be especially common for low-frequency NP expansions. Corpus analysis provides support for all three of these predictions. (shrink)

This paper proposes a formalization of the class of sentences quantified by most, which is also interpreted as proportion of or majority of depending on the domain of discourse. We consider sentences of the form “Most A are B”, where A and B are plural nouns and the interpretations of A and B are infinite subsets of \. There are two widely used semantics for Most A are B: \ > C \) and \ > \dfrac{C}{2} \), where C denotes (...) the cardinality of a given finite set X. Although is more descriptive than, it also produces a considerable amount of insensitivity for certain sets. Since the quantifier most has a solid cardinal behaviour under the interpretation majority and has a slightly more statistical behaviour under the interpretation proportional of, we consider an alternative approach in deciding quantity-related statements regarding infinite sets. For this we introduce a new semantics using natural density for sentences in which interpretations of their nouns are infinite subsets of \, along with a list of the axiomatization of the concept of natural density. In other words, we take the standard definition of the semantics of most but define it as applying to finite approximations of infinite sets computed to the limit. (shrink)

We prove several theorems about the cardinal $\mathfrak{g}$ associated with groupwise density. With respect to a natural ordering of families of nond-ecreasing maps fromω toω, all families of size $< \mathfrak{g}$ are below all unbounded families. With respect to a natural ordering of filters onω, all filters generated by $< \mathfrak{g}$ sets are below all non-feeble filters. If $\mathfrak{u}< \mathfrak{g}$ then $\mathfrak{b}< \mathfrak{u}$ and $\mathfrak{g} = \mathfrak{d} = \mathfrak{c}$ . (The definitions of these cardinals are recalled in the introduction.) (...) Finally, some consequences deduced from $\mathfrak{u}< \mathfrak{g}$ by Laflamme are shown to be equivalent to $\mathfrak{u}< \mathfrak{g}$. (shrink)

Realism about quantum theory naturally leads to realism about the quantum state of the universe. It leaves open whether it is a pure state represented by a wave function, or an impure (mixed) one represented by a density matrix. I characterize and elaborate on Density Matrix Realism, the thesis that the universal quantum state is objective but can be impure. To clarify the thesis, I compare it with Wave Function Realism, explain the conditions under which they are empirically (...) equivalent, consider two generalizations of Density Matrix Realism, and answer some frequently asked questions. I end by highlighting an implication for scientific realism. (shrink)

There has been much recent debate about the nature of the omnivoyant image that introduces Nicholas of Cusa’s De visione Dei. In this paper, I argue that Cusa’s concept of contraction and his ‘radical perspectivism’ lead us toward stretching the concept of omnivoyance beyond a simple dichotomy between a phenomenology of the image and a phenomenology of the icon. Instead of putting such emphasis on what is seen by the omnivoyant, we should think an omnivoyant optics starting from the material (...) milieu from which it sees. To this end, I define the concept of omnivoyance through the concept of the elemental. Using both the concept of an element derived from Presocratic Ionian philosophy and recent French and American continental philosophy, I put these discourses into conversation with Cusa in several ways: the way omnivoyance functions as a substratum of contracted seeing rather than as a transcendence, its operation as a pure frontality without objectifiable aspects, and the way in which omnivoyance implies not only a gaze that sees ‘all and each’ but also a plurality of modes of vision. To help us understand this enlarged concept of omnivoyance, I use the example of animal vision, particularly the gaze of the whale. With respect to cetacean vision, I deploy Melville’s metaphysical speculations in Moby Dick as our primary guide. (shrink)

Underwater object detection plays an important role in research and practice, as it provides condensed and informative content that represents underwater objects. However, detecting objects from underwater images is challenging because underwater environments significantly degenerate image quality and distort the contrast between the object and background. To address this problem, this paper proposes an optical prior-based underwater object detection approach that takes advantage of optical principles to identify optical collimation over underwater images, providing valuable guidance for extracting (...) object features. Unlike data-driven knowledge, the prior in our method is independent of training samples. The fundamental novelty of our approach lies in the integration of an image prior and the object detection task. This novelty is fundamental to the satisfying performance of our approach in underwater environments, which is demonstrated through comparisons with state-of-the-art object detection methods. (shrink)

Ever since Big Data became a mot du jour across social fields, optical metaphors such as the microscope began to surface in popular discourse to describe and qualify its epistemological impact. While the persistence of optics seems to be at odds with the datafication of vision, this article suggests that the optical metaphor offers an opportunity to reflect about the material consequences of the modes of seeing and knowing that currently shape datafied worlds. Drawing on feminist new materialism, (...) the article investigates the optical metaphor as a material-discursive practice that actively constitutes the world, as metaphors imply modes of thinking, knowing and doing that have material enactions. Expanding visual culture theories, the notion of ‘optical unconscious’ is taken up to discuss the tensions between displacement and persistence of optics within datafied worlds, that is, how optical vision is displaced but also mobilised and repurposed by data-driven knowledge. In dialogue with feminist science and technology studies and speculative ethics, I suggest that the datafication of vision offers a chance to reconceptualize the sense of sight towards a sensorial engagement with Big Data premised on responsibility, care, and an ethics of unknowability. Within this framework, vision may be conceived differently, perhaps not only as enhancement and control, but as generator of new possibilities. Ultimately, the article proposes that the visual theories after which Big Data is being imagined matter not only for our understanding of Big Data's epistemic potential, but also for the possibility of shaping emerging data worlds. (shrink)

This paper is an attempt to count the proportion of tautologies of some intermediate logics among all formulas. Our interest concentrates especially on Medvedev’s logic and its fragment over language with one propositional variable.

Concerning Post's problem for Kleene degrees and its relativization, Hrbacek showed in [1] and [2] that if V = L, then Kleene degrees of coanalytic sets are dense, and then for all K ⊆ωω, there are N1 sets which are Kleene semirecursive in K and not Kleene recursive in each other and K. But the density of Kleene semirecursive in K Kleene degrees is not obtained from these theorems. In this note, we extend these theorems by showing that if (...) V = L, then for all K ⊆ ωω, Kleene semirecursive in K Kleene degrees are dense above K. (shrink)

We propose an analogy between optical holography and neural behavior as a hypothesis about the physical mechanisms of neural reuse. Specifically, parameters in optical holography (frequency, amplitude, and phase of the reference beam) may provide useful analogues for understanding the role of different parameters in determining the behavior of neurons (e.g., frequency, amplitude, and phase of spiking behavior).

We present a population density and moment-based description of the stochastic dynamics of domain $${\text{Ca}}^{2+}$$ -mediated inactivation of L-type $${\text{Ca}}^{2+}$$ channels. Our approach accounts for the effect of heterogeneity of local $${\text{Ca}}^{2+}$$ signals on whole cell $${\text{Ca}}^{2+}$$ currents; however, in contrast with prior work, e.g., Sherman et al. :985–995, 1990), we do not assume that $${\text{Ca}}^{2+}$$ domain formation and collapse are fast compared to channel gating. We demonstrate the population density and moment-based modeling approaches using a 12-state Markov (...) chain model of an L-type $${\text{Ca}}^{2+}$$ channel introduced by Greenstein and Winslow :2918–2945, 2002). Simulated whole cell voltage clamp responses yield an inactivation function for the whole cell $${\text{Ca}}^{2+}$$ current that agrees with the traditional approach when domain dynamics are fast. We analyze the voltage-dependence of $${\text{Ca}}^{2+}$$ inactivation that may occur via slow heterogeneous domain [ $${\text{Ca}}^{2+}$$ ]. Next, we find that when channel permeability is held constant, $${\text{Ca}}^{2+}$$ -mediated inactivation of L-type channels increases as the domain time constant increases, because a slow domain collapse rate leads to increased mean domain [ $${\text{Ca}}^{2+}$$ ] near open channels; conversely, when the maximum domain [ $${\text{Ca}}^{2+}$$ ] is held constant, inactivation decreases as the domain time constant increases. Comparison of simulation results using population densities and moment equations confirms the computational efficiency of the moment-based approach, and enables the validation of two distinct methods of truncating and closing the open system of moment equations. In general, a slow domain time constant requires higher order moment truncation for agreement between moment-based and population density simulations. (shrink)

We study the Vapnik–Chervonenkis density of definable families in certain stable first-order theories. In particular, we obtain uniform bounds on the VC density of definable families in finite $\mathrm {U}$-rank theories without the finite cover property, and we characterize those abelian groups for which there exist uniform bounds on the VC density of definable families.

We show that there exist uncountably many pairwise nonisomorphic density-like ideals on $\omega $ which are not generalized density ideals. In addition, they are nonpathological. This answers a question posed by Borodulin-Nadzieja et al. in [this Journal, vol. 80, pp. 1268–1289]. Lastly, we provide sufficient conditions for a density-like ideal to be necessarily a generalized density ideal.

We show that for any ω-r.e. degree d and n-r.e. degree b with d

Mathematical Logic in Philosophy of Mathematics

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Nelson Goodman’s theory of symbol systems expounded in his Languages of Art has been frequently criticized on many counts (cf. list of secondary literature in the entry “Goodman’s Aesthetics” of Stanford Encyclopedia of Philosophy and Sect. 3 below). Yet it exerts a strong influence and is treated as one of the major twentieth-century theories on the subject. While many of Goodman’s controversial theses are criticized, the technical notions he used to formulate them seem to have been treated as neutral tools. (...) One such technical notion is that of the density of symbol systems. This serves to distinguish linguistic symbols from pictorial representations (after Goodman entirely rejected resemblance in that role) and is a crucial part of Goodman’s explanation of what constitutes aesthetic experience (and so indirectly what is art). Thus its significance for Goodman’s theory is fundamental. The aim of this paper is a detailed, logical analysis of this notion. It turns out that Goodman’s definition is highly problematic and cannot be applied to symbol systems in the way Goodman envisaged. To conclude, Goodman’s theory is problematic not just because of its controversial theses but also because of logical problems with the technical notions used at its very core. Hence the controversial claims are not simply contestable, but inaccurately expressed. (shrink)

We define a new type of “shatter function” for set systems that satisfies a Sauer–Shelah type dichotomy, but whose polynomial-growth case is governed by Shelah’s two-rank instead of VC dimension. We identify the least exponent bounding the rate of growth of the shatter function, the quantity analogous to VC density, with Shelah’s $\omega $ -rank.

Typically developing 3-day-old newborns take significantly more forward steps on a moving treadmill belt than on a static belt. The current experiment examined whether projecting optic flows that specified forward motion onto the moving treadmill surface would further enhance forward stepping. Twenty newborns were supported on a moving treadmill without optic flow, with optic flow matching the treadmill’s direction and speed, with optic flow in the same direction but at a faster speed, and in a control condition with an incoherent (...) optic flow moving at the same speed as in the Congruent condition but in random directions. The results revealed no significant differences in the number or coordination of forward treadmill steps taken in each condition. However, the Faster condition generated significantly fewer leg pumping movements than the Random control condition. When highly aroused, newborns made significantly fewer single steps and significantly more parallel steps and pumping movements. We speculate the null findings may be a function of the high friction material that covered the treadmill surface. (shrink)

The human brain shows neuroplastic adaptations induced by motor skill training. However, the description of the plastic architecture of the whole-brain network in resting-state is still limited. In the present study, we aimed to detect how motor training affected the density distribution of whole-brain resting-state functional connectivity (FC) brain in fast-ball student-athletes using resting-state functional magnetic resonance imaging (fMRI) data of student-athletes (SA), and non-athlete healthy controls (NC). The voxel-wise data-driven graph theory approach, namely global functional connectivity density (...) (gFCD) mapping was applied. The results showed that the SA group exhibited significantly decreased gFCD in brain regions centered at left triangular part of inferior frontal gyrus (IFG), extending to opercular part of left IFG and middle frontal gyrus (MFG) compared with NC group. The findings supported the idea of an increased neural efficiency of athletes’ brain in the brain regions associated with attentional-motor modulation and executive control. Furthermore, the behavioral results demonstrated that in the SA group, faster executive control reaction time was associated with smaller gFCD values in left IFG. The findings implied that the motor skill training would decrease the numbers of FC in IFG to accelerate the execution control with high attentional demands, and focus the attention to the target detection the athletes are interested in. (shrink)