11 resultados para Oscillating mirrors

em Bucknell University Digital Commons - Pensilvania - USA


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According to Charles Musser, Huygens had two key innovations for his magic lantern: 1. Images painted on glass instead of etchings on mirrors. 2. An artificial light source was used instead of the reflection of sunlight. (20) Glass slides (often more than one) with hand drawn images are the standard aesthetic for these slides. They are then usually mounted in rectangular wooden frames approx. 4 x 7 inches with a 3 inch circular opening for the image. (Musser 30) The various mechanisms attached to the images are described in the Object Narrative section.

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According to Charles Musser, Huygens had two key innovations for his magic lantern: 1. Images painted on glass instead of etchings on mirrors. 2. An artificial light source was used instead of the reflection of sunlight. (20) Glass slides (often more than one) with hand drawn images are the standard aesthetic for these slides. They are then usually mounted in rectangular wooden frames approx. 4 x 7 inches with a 3 inch circular opening for the image. (Musser 30) The various mechanisms attached to the images are described in the Object Narrative section.

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According to Charles Musser, Huygens had two key innovations for his magic lantern: 1. Images painted on glass instead of etchings on mirrors. 2. An artificial light source was used instead of the reflection of sunlight. (20) Glass slides (often more than one) with hand drawn images are the standard aesthetic for these slides. They are then usually mounted in rectangular wooden frames approx. 4 x 7 inches with a 3 inch circular opening for the image. (Musser 30) The various mechanisms attached to the images are described in the Object Narrative section.

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According to Charles Musser, Huygens had two key innovations for his magic lantern: 1. Images painted on glass instead of etchings on mirrors. 2. An artificial light source was used instead of the reflection of sunlight. (20) Glass slides (often more than one) with hand drawn images are the standard aesthetic for these slides. They are then usually mounted in rectangular wooden frames approx. 4 x 7 inches with a 3 inch circular opening for the image. (Musser 30) The various mechanisms attached to the images are described in the Object Narrative section.

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Wheatstone’s stereoscope placed two mirrors on either side that were mounted at a right angle in order to view the two dissimilar drawings presented (Hankins 148). There are two identical monocular tubes that allow each eye to view the images (Hankins 148). Each eye views the image it was intended to see. The two eyes see slightly different images through this binocular vision (Hankins 148). The combination of the two images creates this illusion of depth and solidarity through their superimposition (Hankins 154). In order to view these images, the eyes were covered from all external light (Clay 152). The stereoscope was first seen as a philosophical toy along with other inventions such as the zoetrope, providing entertainment as well as scientific insight (Hankins 148). The stereoscope above is more similar to the “Holmes Stereoscope”, which transformed Wheatstone’s stereoscope into a handheld version that could be put on a stand (Hawkins 155). He replaced the retina of the eye with a sensitive plate; therefore, the lenses acted as the eyes (Silverman 738). In the video, an embellishment adorns the bottom of the stand that holds up the binocular lens and the images. The lenses are in a wooden frame that has an attached stand that holds the slides of images. There also is a knob on the side of the device that can adjust the lens on the two monocular tubes (Bokander 485).

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The PM3 semiempirical quantum-mechanical method was found to systematically describe intermolecular hydrogen bonding in small polar molecules. PM3 shows charge transfer from the donor to acceptor molecules on the order of 0.02-0.06 units of charge when strong hydrogen bonds are formed. The PM3 method is predictive; calculated hydrogen bond energies with an absolute magnitude greater than 2 kcal mol-' suggest that the global minimum is a hydrogen bonded complex; absolute energies less than 2 kcal mol-' imply that other van der Waals complexes are more stable. The geometries of the PM3 hydrogen bonded complexes agree with high-resolution spectroscopic observations, gas electron diffraction data, and high-level ab initio calculations. The main limitations in the PM3 method are the underestimation of hydrogen bond lengths by 0.1-0.2 for some systems and the underestimation of reliable experimental hydrogen bond energies by approximately 1-2 kcal mol-l. The PM3 method predicts that ammonia is a good hydrogen bond acceptor and a poor hydrogen donor when interacting with neutral molecules. Electronegativity differences between F, N, and 0 predict that donor strength follows the order F > 0 > N and acceptor strength follows the order N > 0 > F. In the calculations presented in this article, the PM3 method mirrors these electronegativity differences, predicting the F-H- - -N bond to be the strongest and the N-H- - -F bond the weakest. It appears that the PM3 Hamiltonian is able to model hydrogen bonding because of the reduction of two-center repulsive forces brought about by the parameterization of the Gaussian core-core interactions. The ability of the PM3 method to model intermolecular hydrogen bonding means reasonably accurate quantum-mechanical calculations can be applied to small biologic systems.

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Atomic magnetometry was performed at Earth's magnetic field over a free-space distance of ten meters. Two laser beams aimed at a distant alkali-vapor cell excited and detected the Rb-87 magnetic resonance, allowing the magnetic field within the cell to be interrogated remotely. Operated as a driven oscillator, the magnetometer measured the geomagnetic field with less than or similar to 3.5 pT precision in a similar to 2 s data acquisition; this precision was likely limited by ambient field fluctuations. The sensor was also operated in self-oscillating mode with a 5.3 pT root Hz noise floor. Further optimization will yield a high-bandwidth, fully remote magnetometer with sub-pT sensitivity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4747206]

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As tissues and organs are formed, they acquire a specific shape that plays an integral role in their ability to function properly. A relatively simple system that has been used to examine how tissues and organs are shaped is the formation of an elongated Drosophila egg. While it has been known for some time that Drosophila egg elongation requires interactions between a polarized intracellular basal actin network and a polarized extracellular network of basal lamina proteins, how these interactions contribute to egg elongation remained unclear. Recent studies using live imaging have revealed two novel processes, global tissue rotation and oscillating basal actomyosin contractions, which have provided significant insight into how the two polarized protein networks cooperate to produce an elongated egg. This review summarizes the proteins involved in Drosophila egg elongation and how this recent work has contributed to our current understanding of how egg elongation is achieved.

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As tissues and organs are formed they acquire a specific shape that plays an integral role in their ability to function properly. A relatively simple system that has been used to examine how tissues and organs are shaped is the formation of an elongated Drosophila egg. While it has been known for some time that Drosophila egg elongation requires interactions between a polarized intracellular basal actin network and a polarized extracellular network of basal lamina proteins, how these interactions contribute to egg elongation remained unclear. Recent studies using live imaging have revealed two novel processes, global tissue rotation and oscillating basal actomyosin contractions, which have provided significant insight into how the two polarized protein networks cooperate to produce an elongated egg. This review summarizes the proteins involved in Drosophila egg elongation and how this recent work has contributed to our current understanding of how egg elongation is achieved.

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Solar energy is the most abundant persistent energy resource. It is also an intermittent one available for only a fraction of each day while the demand for electric power never ceases. To produce a significant amount of power at the utility scale, electricity generated from solar energy must be dispatchable and able to be supplied in response to variations in demand. This requires energy storage that serves to decouple the intermittent solar resource from the load and enables around-the-clock power production from solar energy. Practically, solar energy storage technologies must be efficient as any energy loss results in an increase in the amount of required collection hardware, the largest cost in a solar electric power system. Storing solar energy as heat has been shown to be an efficient, scalable, and relatively low-cost approach to providing dispatchable solar electricity. Concentrating solar power systems that include thermal energy storage (TES) use mirrors to focus sunlight onto a heat exchanger where it is converted to thermal energy that is carried away by a heat transfer fluid and used to drive a conventional thermal power cycle (e.g., steam power plant), or stored for later use. Several approaches to TES have been developed and can generally be categorized as either thermophysical (wherein energy is stored in a hot fluid or solid medium or by causing a phase change that can later be reversed to release heat) or thermochemical (in which energy is stored in chemical bonds requiring two or more reversible chemical reactions).

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In writing “Not in the Legends”, one of the images and concepts which constantly returned was that of pilgrimage. I began to write these poems while studying abroad in London, after having passed the previous semester in France and travelling around Europe. There was something in the repetition of sightseeing— walking six miles in Luxembourg to see the grave of General Patton, taking photographs of the apartment where Sylvia Plath ended her life, bowing before the bones of saints, searching through Père Lachaise for the grave of Théodore Gericault— which struck me as numinous and morbid. At the same time, I came to love living abroad and I grew discontent with both remaining and returning. I wanted the opportunity to live everywhere all the time and not have to choose between home and away. Returning from abroad, I turned my attention to the landscape of my native country. I found in the New England pilgrims a narrative of people who had left their home in search of growth and freedom. In these journeys I began to appreciate the significance of place and tried to understand what it meant to move from one place to another, how one chose a home, and why people searched for meaning in specific locations. The processes of moving from student to worker and from childhood to adulthood have weighed on me. I began to see these transitions towards maturity as travels to a different land. Memory and nostalgia are their own types of pilgrimage in their attempts to return to lost places, as is the reading of literature. These pilgrimages, real and metaphorical, form the thematic core of the collection. I read the work of many poets who came before me, returning to the places where the Canon was forged. Those poets have a large presence in the work I produced. I wondered how I, as a young poet, could earn my own place in the tradition and sought models in much the same way a painter studies the brushstrokes of a master. In the process, I have tried to uncover what it means to be a poet. Is it something like being a saint? Is it something like being a colonist? Or is to be the one who goes in search of saints and colonists? In trying to measure my own life and work based on the precedent, I have questioned what role era and generation have on the formation of identity. I focused my reading heavily on the early years of English poetry, trying to find the essence of the time when the language first achieved the transcendence of verse. In following the development of English poetry through Coleridge, John Berryman, and Allison Titus, I have explored the progression of those basic virtues in changing contexts. Those bearings, applied to my modern context, helped to shape the poetry I produced. Many of the poems in “Not in the Legends” are based on my own personal experience. In my recollections I have tried to interrogate nostalgia rather than falling into mere reminiscence. Rather than allowing myself poems of love and longing, I have tried to find the meaning of those emotions. A dominant conflict exists between adventure and comfort which mirrors the central engagement with the nature of being “here” or “there”. It is found in scenes of domesticity and wilderness as I attempt to understand my own simultaneous desire for both. For example, in “Canned Mangoes…” the intrusion of nature, even in a context as innocuous as a poem by Sir Walter Raleigh, unravels ordinary comforts of the domestic sphere. The character of “The Boy” from Samuel Beckett’s Waiting for Godot proved such an interesting subject for me because he is one who can transcend the normal boundaries of time and place. The title suggests connections to both place and time. “Legends” features the dual meaning of both myths and the keys to maps. To propose something “Not in the Legends” is to find something which has no precedent in our histories and our geographies, something beyond our field of knowledge and wholly new. One possible interpretation I devised was that each new generation lives a novel existence, the future being the true locus of that which is beyond our understanding. The title comes from Keats’ “Hyperion, a Fragment”, and details the aftermath of the Titanomachy. The Titans, having fallen to the Olympians, are a representation of the passing of one generation for the next. Their dejection is expressed by Saturn, who laments: Not in my own sad breast, Which is its own great judge and searcher out, Can I find reason why ye should be thus: Not in the legends of the first of days… (129-132) The emotions of the conquered Titans are unique and without antecedent. They are experiencing feelings which surpass all others in history. In this, they are the equivalent of the poet who feels that his or her own sufferings are special. In contrast are Whitman’s lines from “Song of Myself” which serve as an epigraph to this collection. He contends for a sense of continuity across time, a realization that youth, age, pleasure, and suffering have always existed and will always exist. Whitman finds consolation in this unity, accepting that kinship with past generations is more important that his own individuality. These opposing views offer two methods of presenting the self in history. The instinct of poetry suggests election. The poet writes because he feels his experiences are special, or because he believes he can serve as a synecdoche for everyone. I have fought this instinct by trying to contextualize myself in history. These poems serve as an attempt at prosopography with my own narrative a piece of the whole. Because the earth abides forever, our new stories get printed over the locations of the old and every place becomes a palimpsest of lives and acts. In this collection I have tried to untangle some of those layers, especially my own, to better understand the sprawling legend of history.