Luminous Bodies Research Articles

Robert Halifax, an Oxford Calculator of Shadows

In his commentary on Lombardʼs Sentences, question 1, Robert Halifax OFM presents a remarkably original and inventive optical argument. It compares two pairs of luminous and opaque bodies with two shadow cones until the luminous bodies reach the zenith. In placing two moving human beings into the shadow cones whose moral evolution parallels the size of the shadows, Halifax creates an unprecedented shadow theater equipped with mathematics and theorems of motion from Thomas Bradwardineʼs Treatise on Proportions. This paper is a first attempt at analyzing this imaginary experiment and the mathematics of the infinite it implies. It also shows that optics had new aims through its connexion with the theorems of motion of the Oxford Calculators.

تصوير الآلهة المرتبطة بالسماء في العصرين اليوناني والروماني في مصر

The sky is the basis of the most important cosmic phenomena, as it represents a flat area dependent on the corners of the earth by four pillars, and it forms the upper part of the universe as it is represented as a kind of cover that protects it, and in which the luminous bodies move in it: such as the sun, the moon, stars, clouds and planets. The ancient Egyptian tried from the beginning to get acquainted with the secrets of the surrounding universe, especially the world of the sky with all its components. The sky is responsible for the implementation mechanism of the cosmic system by determining the field that the sun, moon and stars cross daily. She represents the divine mother who is tender to all creatures, as his Lord embodied the sky in the form of a female animal in the form of a lady or the cow of the sky, either in the Greek and Roman eras, the earth gave birth to Gaya, what he saw in it, the star-studded dome, the sky Uranus, and the sky became the seat of the gods.

Analysis for Science Librarians of the 2020 Nobel Prize in Physics: Luminous Bodies, Black Holes, and How They Come Together at the Milky Way’s Heart

ABSTRACT The 2020 Nobel Prize in Physics was awarded to Roger Penrose, Reinhard Genzel, and Andrea Ghez. Penrose was awarded half of the Nobel Prize for creating a groundbreaking black hole theorem that drew on a half-century of theoretical speculations about singularities in general relativity. Ghez and Genzel share the remaining half of the prize for their research teams’ decades of precise observations of the center of the Milky Way, determining from stellar orbits that a supermassive compact object lies at the heart of the galaxy, consistent with predictions for a roughly 4 million solar-mass black hole. This paper describes the science behind the prize, each scientist’s career, and concludes with a citation analysis of each laureate that draws on Web of Science and Scopus data.

Contemporary Hungarian Women’s Writing and Cosmopolitanism

This article investigates contemporary Hungarian women’s writing in the context of cosmopolitan feminism. The literary works explored are Noémi Szécsi’s The Finno-Ugrian Vampire, Noémi Kiss’s Trans and Virág Erdős’s Luminous Bodies: 100 Little Budapest, which I read as examples of a cosmopolitan feminist engagement with urban space. As opposed to the Kantian concept of cosmopolitanism, which has been critiqued for failing to take the experiences of particular social groups and geographical regions into account, cosmopolitan feminism focuses on the local and the embodied. The discussed texts thematise border crossing both on the level of form and content, while they engage with the mundane, affective aspects of everyday life in an emphatically urban setting. This cosmopolitan feminism challenges parochial, heavy, national literary traditions and points towards a distinct feministaesthetics in contemporary Hungarian literature.

Luminous Bodies, Playful Children, and Abusive Grandmothers: Trauma, Dissociation, and Disorganized Attachment in the Early History of Great Perfection (rDzogs Chen) Buddhism

This contribution explores the development of the highest teachings of the “Old School” (rnying ma) of Tibetan Buddhism, known as the Great Perfection (rdzogs chen). Between the tenth and the twelfth centuries, when the “New Schools” (gsar ma) rose to prominence and challenged the legitimacy of the established ones, Dzogchen underwent radical transformations and grew into a complex of contradictory voices. Unlike existing scholarship, which relies exclusively on textual–philological analysis to elucidate the conflictual relationships between sub-traditions like the Mind Series (sems sde), the Seminal Heart (snying thig), and the Crown Pith (spyi ti), this article proffers a transdisciplinary perspective, which complements history with psychological investigations into myth and cognition. Introducing research from cognitive science, trauma studies, attachment theory, and dissociation, it scrutinizes fascinating Dzogchen myths of luminous bodies, playful children, and abusive grandmothers. Ultimately, this transdisciplinary approach results in a new interpretation of the early history of the Great Perfection, as marked by an internal division in the tradition that was the direct result of a historical trauma, which was first processed, then internalized, and finally perpetuated.

Jellyfish galaxies with the IllustrisTNG simulations – I. Gas-stripping phenomena in the full cosmological context

We use IllustrisTNG, a suite of gravity and MHD simulations, to study the demographics and properties of jellyfish galaxies in the full cosmological context. By jellyfish galaxies, we mean satellites orbiting in massive groups and clusters that exhibit highly asymmetric distributions of gas and gas tails. We use the TNG100 run and select galaxies at redshifts $z\le0.6$ with stellar mass exceeding $10^{9.5}{\rm M_\odot}$ and with host halo masses of $10^{13}-10^{14.6}\,{\rm M_\odot}$. Among more than about 6000 (2600) galaxies with stars (and some gas), we identify 800 jellyfish galaxies by visually inspecting their gas and stellar mass maps in random projections. About $31\%$ of cluster satellites are found with signatures of ram-pressure stripping and gaseous tails stemming from the main luminous bodies. This is a lower limit, since the random orientation entails a loss of about $30\%$ of galaxies that in an optimal projection would otherwise be identified as jellyfish. The connection with ram-pressure stripping is further confirmed by a series of findings: jellyfish galaxies are more frequent at intermediate and large cluster-centric distances ($r/R_{\rm 200c}\gtrsim 0.25$); they move through the ICM with larger bulk velocities and Mach numbers than the general cluster population, typically orbiting supersonically and experiencing larger ram pressures. Furthermore, the gaseous tails usually extend in opposite directions to the galaxy trajectory, with no relation between tail orientation and the host's center. The frequency of jellyfish galaxies shows a very weak dependence on redshift $(0\le z\le0.6)$ but larger fractions of disturbed gaseous morphologies occur in more massive hosts and at smaller satellite masses. Finally, jellyfish galaxies are late infallers ($< 2.5-3$ Gyrs ago, at $z=0$) and the emergence of gaseous tails correlates well with the presence of bow shocks in the ICM.

Near-infrared (NIR) up-conversion optogenetics.

Non-invasive remote control technologies designed to manipulate neural functions have been long-awaited for the comprehensive and quantitative understanding of neuronal network in the brain as well as for the therapy of neurological disorders. Recently, it has become possible for the neuronal activity to be optically manipulated using biological photo-reactive molecules such as channelrhodopsin (ChR)-2. However, ChR2 and its relatives are mostly reactive to visible light, which does not effectively penetrate through biological tissues. In contrast, near-infrared (NIR) light (650–1450 nm) penetrates deep into the tissues because biological systems are almost transparent to light within this so-called ‘imaging window’. Here we used lanthanide nanoparticles (LNPs), composed of rare-earth elements, as luminous bodies to activate ChRs since they absorb low-energy NIR light to emit high-energy visible light (up-conversion). Here, we created a new type of optogenetic system which consists of the donor LNPs and the acceptor ChRs. The NIR laser irradiation emitted visible light from LNPs, then induced the photo-reactive responses in the near-by cells that expressed ChRs. However, there remains room for large improvements in the energy efficiency of the LNP-ChR system.

Charge on luminous bodies resembling natural ball lightning produced via electrical arcs through lump silicon.

A phenomenon resembling natural ball lightning can be produced via electrical arcing through silicon. We use lump silicon instead of silicon wafers to achieve higher production rates and larger, longer-lived luminous balls than previously reported. The luminous balls consist of a silicon core surrounded by a porous network of loosely bound silicon dioxide nanoparticles. We find that the balls carry a small net charge on the order of 10(-12) C and propose that the nanoparticles are electrostatically bound to the core due to this charge.

Interview with Professor Alexei Filippenko

B S J A lex F ilippenko Prashant Bhat, Kuntal Chowdhary, Jingyan Wang, and Ali Palla BSJ had the exciting opportunity to interview UC Berkeley’s 9 time “Best Professor” winner, Professor Alexei Filippenko, an astrophysicist and a professor of astronomy. His highly acclaimed research on progenitor stars and explosion mechanisms of different types of supernovae has appeared in numerous TV shows, documentaries, and textbooks. Stemming from our topic on Death and Dying, we discussed the exciting phenomena of star death and the formation of brilliant supernovae. BSJ: To begin, we wanted to know how you got involved in cosmos research and what led you to focus on supernovae? F: As a graduate student at Caltech, I was doing a survey of the five hundred brightest, nearest galaxies in the northern hemisphere to find evidence for a giant black hole that’s swallowing material. Little miniature quasars. Quasars are bright, luminous bodies very far away. We think that they are big black holes swallowing lots of material at the center of galaxies. So in nearby parts of the universe there should be descendents of quasars. In other words, the black holes should still be there, swallowing material at a lower rate. I was doing a survey at the 200-inch (5.1 meter) Hale Telescope at the Palomar Observatory with my former thesis advisor at Caltech, Wal Sargent. This is now February of 1985, I’m a post-doctoral scholar now at Berkeley and at the end of the fifth night of the five night observing run I had time left for just two more galaxies to observe. I had a hundred possibilities because the survey was still in its early stages—I chose a galaxy almost at random because the picture of it looked interesting. So I said, “let’s survey that one.” When we pointed the telescope to that galaxy, we B erkeley S cientific J ournal • D eath and D ying • S pring 2013 • V olume 17 • I ssue 2 • 1

Surface-Enhanced Emission from Single Semiconductor Nanoribbons

Emission enhancement from single semiconductor CdSe nanoribbons by introduction of surface plasmon polaritons (SPPs) via Au contacts is studied. Scanning confocal microscopy is employed to investigate the emission enhancement behavior via photoluminescence measurements. Large enhancement factors of 77-130 at a peak emission of CdSe of ∼710 nm are obtained, which are ascribed to the gain-assisted propagation of the short-range mode of SPPs. Our findings open the exciting possibilities for high-efficiency SPP-enhanced light-emitting devices based on luminous bodies with finite lateral dimensions.

レーザプラズマ式３Ｄディスプレイにおける点列を用いた物体表現

This research proposes a method of representing objects for a 3D display device that uses a pulse laser and generates plasma luminous bodies in arbitrary positions in midair. By using a xyz-scanner, the device controls the position of plasma luminous bodies that appear and disappear one by one in 1 kHz. The device can display an object in one stroke in midair. We propose our method of representing primitive objects— polygons, polyhedrons and curved surface objects— in consideration of hardware limitations and human visual characteristics, and evaluate the objects in experiments. As a result, polygons can be represented visually, effectively reducing the scanner burden by smoothing accelerations at corners and increasing the plasma density; polyhedron faces are best drawn one by one; and when curved surface objects are drawn using spiral, we can stably perceive them.

Nonuniqueness of stationary accretion in the Shakura model

We investigate the accretion onto luminous bodies with hard surfaces within the framework of newtonian theory. The accreting gases are assumed to be polytropes and their selfgravitation is included. A remarkable feature of the model is that under proper boundary conditions some parameters of the sonic point are the same as in the Bondi model and the relation between luminosity and the gas abundance reduces to an algebraic relation. All that holds under assumptions of stationarity and spherical symmetric. Assuming data that are required for the complete specification of the system, one finds that generically for a given luminosity there exist two solutions with different compact cores.

President’s message

As we celebrate the 50th anniversary of the founding of echocardiography this year, it is appropriate that we recognize both the inventors and the inventions that have made echocardiography the robust imaging technique it is today. At the same time, it is interesting to put them into context by noting what other events were occurring in the world of cardiology, medicine, and engineering. Here then, in chronological order, is a brief history of echocardiography. Although there are many early discoveries and many starting points of echocardiography, Johann Christian Doppler’s 1842 description of the effect which bears his name is perhaps the best. He noted that “the color of luminous bodies, just like the pitch of a sounding body, changes with motion of the body to and from the observer.” At the time, cardiology was not a medical specialty; yet in 1844 Bernard performed the first cardiac catheterization—his patient was a horse! Thirty-nine years later, in 1881, Jacques and Pierre Curie (husband of Marie) discovered the principle of piezoelectricity—an electric polarization produced by the compression or the expansion of crystals in the direction of the axis of symmetry. Soon thereafter, Einthoven began experimenting with the string galvinometer, and in 1903 he recorded the first ECG and PQRST waves. In addition to winning the Nobel Prize in 1924, the invention of the electrocardiogram also led to the creation of the specialty of cardiology, in a very interesting way. Possession of and knowing how to use a technology (an ECG machine), rather than a purely cognitive set of skills, defined a physician as a cardiovascular specialist. The first half of the twentieth century saw continued early developments in echocardiography. In 1917 (Jean) Paul Langevin was the first to attempt to use the piezoelectric effect as sonar, to detect U-boats. Unfortunately he succeeded only in heating water and killing fish. In 1941 Karl T. Dussik was the first to attempt to use ultrasound in medicine, although he examined the brain and not the heart. That same year, A. Cournand and D. Richards perfected Werner Forssmann’s 1929 experiment on himself, and invented modern cardiac catheterization, for which they later won the Nobel Prize in 1955. In 1950, W.D. Keidel was the first to use ultrasound on the heart. He reported his (unsuccessful) attempts to measure cardiac volumes by recording synchronous ultrasound and phonocardiograms in a paper entitled: “On a new method for the registration of volume changes of the human heart.” Two years later, J.J. Wild and J.M. Reid and D. Howry and W. Bliss independently developed the first 2-dimensional ultrasound imaging systems, but did not attempt to image the heart. In 1953, Inge Edler (a physician) and C. Hellmuth Hertz (an engineer) borrowed a shipyard sonar machine made by Siemens used for detecting structural flaws in boat hulls. They are credited with performing the first human echocardiogram, which they termed ultrasound cardiography (UCG). Images were crude, but the posterior left ventricular wall and anterior mitral leaflet were visualized (although the valve was initially thought to be the anterior left atrial wall). This was the first successful imaging of any organ for medical purposes, and Edler and Hertz won the Lasker award in 1977 for the invention of medical ultrasound imaging. While Edler continued to be a pioneer in echocardiography, Hertz, whose father won the Nobel Prize in physics, went on to invent the ink jet printer. Hertz also advised Siemens not to bother with cardiac ultrasound because he saw little commercial future in it, although he did stay in the field long enough to invent the first mechanical 2-dimensional cardiac scanner in 1971. Other echocardiography pioneers included Hsu Chih-Chang (China), Sven Effert (Germany), and Schmitt and Braun (Germany). In 1956 S. Satumora, Yoshida, and Nimura were the first to apply the Doppler principle to the use of ultrasound to detect cardiac motion (but not blood flow). That same year, the videotape recorder was invented and Paul Zoll performed the first external defibrillation. The use of cardiac ultrasound was growing; in 1957, the year of Sputnik, J.J. Wild and J.M. Reid identified a myocardial infarction in vitro, using both M-mode and 2-dimensional echocardiograhpy in the US, and published their images in the American Heart Journal. Cardiovascular medicine was thriving as well. In 1958 Sones performed the first selective coronary angiogram, Ross performed the first transseptal catheterization, and Sherry first used streptokinase to treat acute myocardial infarction in 24 patients. To be continued next month…

Hobbes et Gassendi: la psychologie dans le projet mécaniste

L'amitié et l'affinité intellectuelle qui caractérisèrent les rapports de Hobbes avec Gassendi forment un tissu ténu dont il n'est point aisé de démêler la trame. Aux côtés de points de convergence clairement définis, telle la commune aversion envers le dualisme et l'innéisme cartésiens, et par-delà des divergences non moins nettes dans leurs orientations philosophiques particulières, le sens des parcours maintes fois parallèles doit encore être éclairé de façon circonstanciée. Le terrain privilégié sur lequel élever une confrontation étroite entre deux auteurs est sans doute la construction d'une psychologie profondément marquée par des prémisses empiriques et dont l'orientation vise à établir une relation très étroite entre les processus de la perception, du désir (appetitus) et de la volonté avec ce qui les détermine matériellement et mécaniquement. On peut même affirmer que les écrits de Gassendi rédigés au tout début des années 1640 définissent une série d'hypothèses innovatrices sur lesquelles s'inscrit une certaine convergence avec les élaborations de Hobbes à elles contemporaines. Sous ce profil, le groupe de textes remontant aux années 1640-41, et où le philosophe d'Aix s'interroge sur la nature des phénomènes lumineux, est emblématique. L'explication du comportement des corps lumineux en terme de systole et de diastole, l'interprétation de la propagation de la lumière s'inspirant de la pure actualité cinématique (en polémique ouverte et explicite envers les thèses de la Dioptrique de Descartes sur la luminosité comme simple inclinaison au mouvement), le vacuisme (qui est propre à Gassendi, servant justement à rendre compte des phénomènes d'expansion et de contraction des sources lumineuses et qui, à cette époque, n'était pas encore exclu par Hobbes), la représentation, enfin, tout à fait matérielle et mécanique des phénomènes d'irradiation, voilà autant d'aspects de la recherche de Gassendi qui peuvent facilement être confrontés aux écrits de Hobbes.

Particle motion in the gravitational field of a charged, radiating body

The motion of test bodies is examined in the framework of the Vaidya–Bonner model of a charged, radiating mass. The null and time-like geodesic equations are obtained exactly. Similar equations are obtained exactly for the case of charged test particles. It is demonstrated that the luminosity of the central body induces a relative motion between positive and negative test charges, leading to accretion disk temperatures for luminous bodies which are higher than those of non-radiating bodies.

Leonardo da Vinci's solution to the problem of the pinhole camera

The longstanding challenge of the pinhole camera for medieval theorists was explaining why luminous bodies cast onto a screen different images at different distances from the screen.

Projectile Detection of Luminous and Nonluminous Bodies

In a large hyperballistics range, detection of projectiles atstations becomes more complex. Range length permits variation of projectile luminosity and requires greater area for detection. A technique has been devised, using electrooptics, triggering instrumented stations with luminous or nonluminous projectiles. The phototube circuit response, effect of velocity, and effect of light screen thickness on performance are discussed. Data on performance are presented for velocities of 10 000 to 21 000 feet per second. Performance is predicted for velocities of 40 000 and 60 000 feet per second. Nonluminous models as small as 3/16-inch diameter spheres have been detected at a velocity of 21 000 feet per second.

Spherical Plasmoids in Low Pressure Electrodeless Discharges†

ABSTRACT ‘ Plasmoids ’, of the kind originally observed by R. W. Wood, are luminous plasma bodies occasionally found in low pressure electrodeless discharges. Experiments with spherical plasmoids in. argon at a pressure of 10−4 mm Hg show that the electron temperatures are in the region of 105 to l·5×l05°c and the electron number density is of the order 108 cm−3. Plasmoids are affected by the presence of a probe, and variation in the probe potential can cause large changes in the size of the plasmoid. The plasma equation of Tonks and Laugmuir, for spherical symmetry and for ion generation proportional to the electron density, is solved and an approximate theory is advanced to explain some of the effects observed.

Preliminary Note on the Nature of the Luminous Bodies of Watasenia scintillans (Berry)

Preliminary Note on the Nature of the Luminous Bodies of Watasenia scintillans (Berry)

Our Astronomical Column

THE SYSTEM OF CASTOR.—A very interesting discovery with regard to this well-known binary star has been made by Dr. Belopolsky (Bull. Acad. Imp. Set. St. Petersbourg, vol. iv. No. 3). In addition to the two luminous bodies, which perform their revolution in a period of about 1000 years, Dr. Belopolsky's observations indicate that the brighter star, α1 Geminorum, has a dark companion very similar to that of Algol, except that it never produces eclipses. The existence of this dark body was suspected in 1894, and it was fully confirmed by photographs of the spectrum taken at Pulkowa early in the present year, showing periodic changes in the velocity of the star along the line of sight. Thirteen photographs were obtained, and from these the velocities of α1, Geminorum towards or away from the sun were deduced. Although the available data are insufficient for a complete determination of the orbit, it may be taken to be circular as a first approximation, and a period of revolution of 2˙98 days sufficiently accords with the spectroscopic measurements. The proper motion of the system of α1, is 1˙0 geographical mile (= 4˙6 English miles) per second away from the sun, while the relative orbital velocity is 4˙5 geographical miles (20˙7 English miles) per second.