Ancient Maya documents concerning the movements of Mars

A large part of the pre-Columbian Maya book known as the Dresden Codex is concerned with an exploration of commensurate relationships among celestial cycles and their relationship to other, nonastronomical cycles of cultural interest. As has long been known, pages 43b–45b of the Codex are concerned with the synodic cycle of Mars. New work reported here with another part of the Codex, a complex table on pages 69–74, reveals a concern on the part of the ancient Maya astronomers with the sidereal motion of Mars as well as with its synodic cycle. Two kinds of empiric sidereal intervals of Mars were used, a long one (702 days) that included a retrograde loop and a short one that did not. The use of these intervals, which is indicated by the documents in the Dresden Codex, permitted the tracking of Mars across the zodiac and the relating of its movements to the terrestrial seasons and to the 260-day sacred calendar. While Kepler solved the sidereal problem of Mars by proposing an elliptical heliocentric orbit, anonymous but equally ingenious Maya astronomers discovered a pair of time cycles that not only accurately described the planet's motion, but also related it to other cosmic and terrestrial concerns.

Definition of a metal-dependent/Li(+)-inhibited phosphomonoesterase protein family based upon a conserved three-dimensional core structure.

Inositol polyphosphate 1-phosphatase, inositol monophosphate phosphatase, and fructose 1,6-bisphosphatase share a sequence motif, Asp-Pro-(Ile or Leu)-Asp-(Gly or Ser)-(Thr or Ser), that has been shown by crystallographic and mutagenesis studies to bind metal ions and participate in catalysis. We compared the six alpha-carbon coordinates of this motif from the crystal structures of these three phosphatases and found that they are superimposable with rms deviations ranging from 0.27 to 0.60 A. Remarkably, when these proteins were aligned by this motif a common core structure emerged, defined by five alpha-helices and 11 beta-strands comprising 155 residues having rms deviations ranging from 1.48 to 2.66 A. We used the superimposed structures to align the sequences within the common core, and a distant relationship was observed suggesting a common ancestor. The common core was used to align the sequences of several other proteins that share significant similarity to inositol monophosphate phosphatase, including proteins encoded by fungal qa-X and qutG, bacterial suhB and cysQ (identical to amtA), and yeast met22 (identical to hal2). Evolutionary comparison of the core sequences indicate that five distinct branches exist within this family. These proteins share metal-dependent/Li(+)-sensitive phosphomonoesterase activity, and each predicted tree branch exhibits unique substrate specificity. Thus, these proteins define an ancient structurally conserved family involved in diverse metabolic pathways including inositol signaling, gluconeogenesis, sulfate assimilation, and possibly quinone metabolism. Furthermore, we suggest that this protein family identifies candidate enzymes to account for both the therapeutic and toxic actions of Li+ as it is used in patients treated for manic depressive disease.

Photoconductivity and Electro-Optical Properties of Wide Band Gap Metal Oxides

The PhD activity described in this Thesis was focused on the study of metal-oxide wide-bandgap materials, aiming at fabricating new optoelectronic devices such as solar-blind UV photodetectors, high power electronics, and gas sensors. Photocurrent spectroscopy and DC photocurrent time evolution were used to investigate the performance of prototypes under different atmospheres, temperatures and excitation wavelengths (or dark conditions). Cathodoluminescence, absorption spectroscopy, XRD and SEM were used to assess structural, morphologic, electrical and optical properties of materials. This thesis is divided into two main sections, each describing the work done on a different metal-oxide semiconductor. 1) MOVPE-grown Ga2O3 thin films for UV solar-blind photodetectors and high power devices The semiconducting oxides, among them Ga2O3, have been employed for several decades as transparent conducting oxide (TCO) electrodes for fabrication of solar cells, displays, electronic, and opto-electronic devices. The interest was mainly confined to such applications, as these materials tend to grow intrinsically n-type, and attempts to get an effective p-type doping has consistently failed. The key requirements of TCO electrodes are indeed high electrical conductivity and good transparency, while crystallographic perfection is a minor issue. Furthermore, for a long period no high-quality substrates and epi-layers were available, which in turn impeded the development of a truly full-oxide electronics. Recently, Ga2O3 has attracted renewed interest, as large single crystals and high-quality homo- and hetero-epitaxial layers became available, which paved the way to novel application areas. Our research group spent the last two years in developing a low temperature (500-700°C) MOVPE growth procedure to obtain thin films of Ga2O3 on different substrates (Dept. of Physics and IMEM-CNR at UNIPR). We obtained a significant result growing on oriented sapphire epitaxial films of high crystalline, undoped, pure phase -Ga2O3 (hexagonal). The crystallographic properties of this phase were investigated by XRD, in order to clarify the lattice parameters of the hexagonal cell. First design and development of solar blind UV photodetectors based on -phase was carried out and the optoelectronic performance is evaluated by means of photocurrent spectroscopy. The UV-response is adequately fast and reliable to render this unusual phase a subject of great interest for future applications. The availability of a hexagonal phase of Ga2O3 stable up to 700°C, belonging to the same space group of gallium nitride, with high crystallinity and tunable electrical properties, is intriguing in view of the development of nitride-based devices, by taking advantage of the more favorable symmetry and epitaxial relationships with respect to the monoclinic β-phase. In addition, annealing at temperatures higher than 700°C demonstrate that the hexagonal phase converts totally in the monoclinic one. 2) ZnO nano-tetrapods: charge transport mechanisms and time-response in optoelectronic devices and sensors Size and morphology of ZnO at the nanometer scale play a key role in tailoring its physical and chemical properties. Thanks to the possibility of growing zinc oxide in a variety of different nanostructures, there is a great variety of applications, among which gas sensors, light emitting diodes, transparent conducting oxides, solar cells. Even if the operation of ZnO nanostructure-based devices has been recently demonstrated, the mechanisms of charge transport in these assembly is still under debate. The candidate performed an accurate investigation by photocurrent spectroscopy and DC-photocurrent time evolution of electrical response of both single-tetrapod and tetrapod-assembly devices. During the research done for this thesis, a thermal activation energy enables the performance of samples at high temperatures (above about 300°C). The energy barrier is related to the leg-to-leg interconnection in the assembly of nanotetrapods. Percolation mechanisms are responsible for both the very slow photo-response (minutes to hours or days) and the significant persistent photocurrent. Below the bandgap energy, electronic states were investigated but their contribution to the photocurrent are two-three order of magnitude lower than the band edge. Such devices are suitable for employ in photodetectors as well as in gas sensors, provided that the mechanism by which the photo-current is generated and gas adsorption on the surface modify the conductivity of the material are known.

Inventions and industry in the art of Howard Finster

This paper examines Finster’s collection of Inventions of Mankind and his paintings of American industrial icons such as Henry Ford and Eli Whitney. Additionally, this study explores Finster’s compulsive artistic productivity and his experimentation with mechanisms designed to create self-sustaining energy. By providing a comprehensive overview of Howard Finster’s fascination with inventions and industry, this paper serves to provide new insight and dimension into the often over-generalized interpretations of his extensive body of work

Beautiful victims : childhood and the holocaust in the work of Gottfried Helnwein

"For the past three decades, contemporary artist Gottfried Helnwein has shocked viewers with his Holocaust-related paintings, drawings and installations. Born in Austria in 1948, Helnwein witnessed the immediate aftermath of World War II in Europe from a child’s perspective. Consequently, the horrifying images summoned from Helnwein’s imagination are inspired by the memories and repercussions of this tragedy. His work addresses his parents’ unwillingness to speak of the atrocities as well as the exploitation of the Holocaust in contemporary popular media. His work questions not only how such a tragedy could have taken place, but also how contemporary perception of this event has been affected by total media saturation and the passage of time. To shock viewers, Helnwein portrays strikingly realistic images of distressed, wounded and morally ambiguous children in works that have been regarded as controversial and outspoken"

All the rest is merely exploitation and perseverance : the poster art of Frank Kozik

"The history of poster art tends to focus on the art of Henri Toulouse-Latrec, Jules Cheret, and Alfonse Mucha, while leaving out or barely mentioning the work of artists such as Wes Wilson, Stanley Mouse, and Alton Kelley. The aim of this thesis is to widen the gaze of poster art by centering on a contemporary rock poster artist: Frank Kozik. By focusing on formal and sociological analysis ofa number of Kozik's posters, I illustrate how he not only fits in with the arc of poster art development, but also influences it into the next century"

Closer to life : the work of sari dienes

Like many of her female contemporaries, artist Sari Dienes’s contributions to the art historical dialogue have been largely overlooked in favor of her male counterparts. Often seen as a mentor and mother figure to neo-Dada artists Jasper Johns and Robert Rauschenberg, Dienes was an active member of the New York avant-garde circle surrounding composer/choreographer duo John Cage and Merce Cunningham in the 1950s and 1960s. These social relationships are central to the existing discourse on Sari Dienes, while her work remains little discussed. The fact that her dynamic, ever-changing style lacked aesthetic consistency was commonly lamented by notable figures such as Betty Parsons, however, I argue that Dienes’s diverse oeuvre is unified by her philosophies on art and life. The unification of art and life, denoted clearly by Dienes’s use of the found object, experimentation and chance happenings, and sensory experience, marks her as an innovator and catalyst in the neo-Dada movement as well as in other experimental art endeavors that took place in the aftermath of Abstract Expressionism.

Graveyards to Glamour : Development of Sexualized Angel Imagery in American Art and Advertising

Images of female angels in American art and advertisements have been sexualized in the late twentieth and early twenty-­‐first centuries. Companies such as Victoria’s Secret have appropriated the image of female angels, which first appeared at the beginning of the nineteenth century, and clothed them in lingerie in order to sell a product. This Masters Research Paper explores the evolution of female angelic imagery in the United States in order to understand how and when the image of angels began to be sexualized and used in advertising. Angels in art have been studied extensively; however, there has been no work done which examines how the angels in art and advertising have been sexualized. Nor has any work been done to map the evolution of female angelic imagery in American art. This Masters Research Paper will fill that gap in scholarship.

Creating Beautiful Art: Challenging Comfort

Creating Beautiful Art: Challenging Comfort investigates the notion of beauty and its relationship to art while asking what is and can be art. Throughout the work, research supports the concept of beauty elevating art even with the use of atypical, unconventional, or mundane materials. Direct attention is given to this idea by completion of a Creative Capstone Project. I incorporated aesthetics with unconventional materials in order to challenge viewing comfort, as well as added value to the existing body of knowledge concerning beauty in contemporary art. The reflective section summarizes the importance of unconventional materials creating beauty in art in order to progress itself linearly by creating and reinventing the new.

Molecular signature of highly conductive metal-molecule-metal junctions

The simplicity of single-molecule junctions based on direct bonding of a small molecule between two metallic electrodes makes them an ideal system for the study of fundamental questions related to molecular electronics. Here we study the conductance properties of six different types of molecules by suspending individual molecules between Pt electrodes. All the molecular junctions show a typical conductance of about 1G0 which is ascribed to the dominant role of the Pt contacts. However, despite the metalliclike conductivity, the individual molecular signature is well expressed by the effect of molecular vibrations in the inelastic contribution to the conductance.

Common origin for surface reconstruction and the formation of chains of metal atoms

During the fracture of nanocontacts gold spontaneously forms freely suspended chains of atoms, which is not observed for the isoelectronic noble metals Ag and Cu. Au also differs from Ag and Cu in forming reconstructions at its low-index surfaces. Using mechanically controllable break junctions we show that all the 5d metals that show similar reconstructions (Ir, Pt, and Au) also form chains of atoms, while both properties are absent in the 4d neighbor elements (Rh, Pd, and Ag), indicating a common origin for these two phenomena. A competition between s and d bonding is proposed as an explanation.