http://hdl.handle.net/1813/39 Tue, 21 May 2013 14:10:37 GMT 2013-05-21T14:10:37Z http://ecommons.library.cornell.edu:80/retrieve/569/grad_school2.jpg http://hdl.handle.net/1813/39 http://hdl.handle.net/1813/33230 Title: The cost and quality of school bus transportation and the distribution of state aid for transportation in New York State. Authors: Crane, Edmund Harold Abstract: The final purpose of this study was to suggest a method of distributing state aid for transportation in accordance with the equalization principle. Description: 196 l. illus. 28 cm. Fri, 01 Jan 1943 00:00:00 GMT http://hdl.handle.net/1813/33230 1943-01-01T00:00:00Z http://hdl.handle.net/1813/33154 Title: MEANS OF TRAVEL AND TRANSPORTATION IN THE OTTOMAN EMPIRE Authors: Mouhtar, S.F. Wed, 01 May 1929 00:00:00 GMT http://hdl.handle.net/1813/33154 1929-05-01T00:00:00Z http://hdl.handle.net/1813/31387 Title: Identification Of A Novel, Rapid Mechanism To Alleviate The Nucleosome Barrier To Transcription Authors: Petesch, Steven Abstract: To efficiently transcribe genes, RNA Polymerase II (Pol II) must overcome the barrier imposed by nucleosomes and higher order chromatin structure. Many genes, including Drosophila melanogaster Hsp70, undergo changes in chromatin structure upon activation. It has long been thought that changes to chromatin structure occur co-transcriptionally as a result of Pol II movement through the gene and recruitment of Pol II associated factors that disrupt chromatin structure. In this dissertation, I demonstrate that, upon activation, the changes in chromatin structure of Drosophila melanogaster's Hsp70 gene occur in an extremely rapid manner that is independent of act ive transcription of the gene. In addition, these changes extend beyond the gene encoding unit to natural chromatin insulating elements. From a series of targeted RNAi screens I indentified four proteins necessary for the rapid, transcriptionindependent loss of nucleosomes at the Hsp70 locus following heat shock and an ordered mechanism through which they function. The first factor identified, heat shock factor (HSF), is the master transcriptional activator of heat shock genes and is rapidly recruited to the gene within seconds of heat shock, and binds cooperatively with the second factor, GAGA Factor, already bound to the gene. HSF is necessary for the recruitment of the third identified factor, dTip60, a histone acetyltransferase that acetylates histo ne H2A lysine 5. This acetylation is necessary for the enzymatic activation of the fourth and final factor, Poly(ADP)-Ribose Polymerase (PARP), which catalyzes the formation Poly(ADP-ribose). PARP is associated with the 5' end of Hsp70 before heat shock, and its enzymatic activity is rapidly induced by heat shock. This activation causes PARP to redistribute throughout the Hsp70 loci and Poly(ADP-ribose) to concurrently accumulate in the wake of PARP's redistribution. Both the protein PARP and its catalytic activity are necessary for the rapid loss in nucleosome structure of Hsp70 upon heat shock and full transcriptional activation of Hsp70. In this dissertation I propose a novel mechanism to overcome the nucleosome barrier to achieve full transcriptional activation through the enzymatic activation of PARP which results in a rapid, transcription-independent, locus-wide disruption of chromatin structure. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31387 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31388 Title: Opto Acoustic Oscillator Using Silicon Rf Mems Based Optical Modulator Authors: Sridaran, Suresh Abstract: Mechanical resonators have been used for the last few decades as the frequency selection element of high frequency oscillators and radio frequency filters due to their high quality factors. Mechanical resonators scaled to the micro scale, called micromechanical resonators, offer the promise of integration of these high precision frequency selection elements along with microelectronics on the same substrate. Scaling to the micro scale allows micromechanical resonators operate at desired higher frequencies compared to their macroscopic counterparts. This along with the advantage of lower manufacturing cost due to the microelectronic fabrication process used for the their fabrication have made them attractive candidates for use in modern wireless radio devices. Micromechanical resonators excited and sensed using electrostatic air gap capacitive transduction have been shown to have very high quality factors close to the material loss limit. While electrostatic air gap transducers are easy to co-fabricate with microelectronics in a shared process, it suffers from lower sensitivity at higher frequencies making it difficult to use in high frequency applications. Cavity optomechanical systems, where a mechanical resonator is also an optical resonance cavity, has been shown to be one of the most sensitive methods for detecting mechanical motion. Such systems use shifts in the optical resonance frequency of the optomechanical resonator to sense mechanical motion. Presently, these optomechanical systems are used for measuring mechanical thermal noise displacement or mechanical motion actuated by optical forces. In this dissertation, a monolithic scheme for integration of electrostatic capacitive actuation of mechanical resonators with optical sensing using silicon optomechanical disk resonators and waveguides is presented. To obtain an optically sensed electrostatically actuated mechanical resonator, a coupled disk geometry is used, where one disk acts as the sensing optomechanical resonator while mechanical vibrations are excited through electrodes around the other disk. The electrostatically actuated optomechanical resonator combines the frequency filtering response of a mechanical resonator with the optical amplitude modulation property of the optomechanical resonator thereby creating an integrated narrowband optical modulator.This narrow band optical modulator called the acousto optic modulator and fabricated on the silicon device layer of a silicon on insulator substrate modulates output light when the electrical input is around the mechanical resonance. For disks of 10[MICRO SIGN]m radius, the radial vibrational modes are observed as optical modulation around 236MHz with an extinction ratio of 12dB for a DC bias of 20V, RF input power of 5dBm and optical quality factor of 53,000. Scaling the radius of the disks to 3.8/mum increases the observed frequency of the fundamental mode resonance to 706MHz along with the second radial vibrational mode to 1.93GHz. An alternate geometry using ring resonators shows multiple mechanical modes up to 3.5GHz making this one of the highest observed mechanical frequencies with air gap electrostatic actuation. An important application of mechanical resonator is in frequency selection as part of an oscillator loop. Implementing the acousto optic modulator in an oscillator is similar to the opto-electronic oscillator (OEO), which is the current state-of-art oscillator in the few GHz regimes that uses optical feedback in the oscillation loop. The optical output from the modulator is converted back to the electrical domain using a high speed optical detector and then amplified and fed back into the modulator. Employing this technique, an opto-acoustic oscillator (OAO) has been demonstrated at the mechanical frequency of 236MHz of the disk resonator with an output power of 6.5dBm and a phase noise of 65dBc/Hz at 1kHz offset. Additionally, an OAO operating at 1.12 GHz with an output power of 8.8dBm and -65dBc/Hz at 10kHz offset is demonstrated using the ring resonator based modulator. In summary, this work presents a combined electrical-optical micromechanical system fabricated on a CMOS compatible process thereby opening up the possibility of novel devices for future electo-optic-mechanical multi domain systems. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31388 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31386 Title: Plant Genotypic Diversity And Its Influence On Arthropod Communities Authors: Mcart, Scott Abstract: Genotypic diversity varies markedly among populations of organisms, however the ecological consequences of intraspecific diversity are poorly understood. Here I directly compare the effects of plant species and genotypic diversity on arthropod communities and ecosystem functioning. Through behavioral observations, field experiments, and laboratory assays, I show contrasting mechanisms by which arthropod species richness and evenness are altered by each type of plant diversity. I then show how genotypic diversity of the common evening primrose (Oenothera biennis) reduces herbivory by changing herbivore behavior and physiology, ultimately decreasing consumption efficiency. Finally, I show how O. biennis genotypic diversity attenuates induced plant resistance to the Japanese beetle (Popillia japonica), indirectly increasing plant susceptibility to three native seed predators. As a result, this highly invasive beetle actually increases the fitness of O. biennis by consuming it. Overall, I show that plant genotypic diversity contributes substantially to the structure and functioning of arthropod communities through both direct and indirect mechanisms. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31386 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31385 Title: Perturbing Warped Throats: Explicit Predictions From A Corner Of The Landscape Authors: Gandhi, Sohang Abstract: Obtaining robust predictions from string theory has proven to be very challenging, simultaneously due to the vast number of possible vacua in the landscape and to the overwhelming geometric complexity of Calabi-Yau manifolds. We will present a promising new approach, applicable in the subset of string theory vacua possessing a warped throat region, in the form of a systematic procedure for perturbing Calabi-Yau cones. Most of the complexity of the bulk geometry is filtered out by the warping and effective descriptions for models constructed in the warped regions can be explicitly obtained. We will demonstrate the application of our procedure by analyzing the potential for angular moduli of an anti-D3-brane sitting at the tip of a Klebanov-Strassler throat. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31385 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31384 Title: A Controller Design Framework For Bipedal Robots: Trajectory Optimization And Event-Based Stabilization Authors: Bhounsule, Pranav Abstract: This thesis presents a model-based controller design framework for bipedal robots that combines energy-efficiency with stability. We start with a physics based model for the robot and its actuators. Next, the parameters of the model are identified in a series of bench experiments. Then we formulate an energy-optimal trajectory control problem. Our energy metric is the total cost of transport (TCOT) and is defined as the energy used per unit weight per unit distance travelled. We solve the trajectory control problem using parameter optimization software and an adequately fine grid. To implement the energy-optimal solution on the physical robot, we follow a two part approach. First, we approximate the converged optimal solution with a simpler representation that sufficiently captures the optimality. The resulting walking gait is called the nominal trajectory. Second, we stabilize the nominal trajectory using an eventbased, discrete, intermittent, feed-forward controller. Our stabilizing controller tries to regulate heuristically chosen quantities in a step, like step length or step velocity, doing feedback on a few key sensor data values collected at key points in a step. Using this control framework our knee-less 2D 1 m tall 9.9 kg 4-legged bipedal robot, Ranger, achieved two feats: one, Ranger walked stably with a TCOT of 0.19, which is the lowest TCOT ever achieved by a legged robot on level terrain and, two, Ranger walked non-stop for 65 km or 40.5 miles without battery recharge or touch by a human, setting a distance record for legged robots. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31384 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31383 Title: Extremely Efficient And Ultrafast: Electrons, Holes, And Their Interactions In The Carbon Nanotube Pn Junction Authors: Gabor, Nathaniel Abstract: The electronic properties of charge carriers in carbon nanotubes exhibit striking similarities to relativistic elementary particles. A remarkable prediction of relativistic quantum mechanics is the ability of particle-antiparticle pairs to be created and annihilated when interacting with other high-energy particles. In this thesis, I discuss optoelectronic experiments that probe the extremely efficient generation of electron-hole pairs and the (ultra-) fast transit of these electrons and holes through nanotube PN junction photodiodes. Spatially, spectrally, and temporally resolved photocurrent measurements suggest that that the generation of multiple electron-hole pairs from a single high energy carrier is extremely efficient, and that electrons and holes may undergo electron-hole pair annihilation as they transit the junction on sub-picosecond time scales. These processes, analogous to relativistic particle-antiparticle creation and annihilation, set new boundaries for the performance limits of nanoscale optoelectronic devices. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31383 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31381 Title: Greening Event Goers At The 2010 Fifa World Cup: A User Perspective Assessment Of Sustainable Transport Strategies Authors: Izawa, Masumi Abstract: Mega sporting events are tourist-based events that have recently begun subscribing to the sustainable development framework by greening its events to curtail environmental impact, especially on travel. The sustainable transport strategies outlined in the Green Goal Program for the 2010 FIFA World Cup aimed to reduce car use in favor of public transport, promote environmental awareness, and encourage behavior change. This thesis is an assessment of the structural and informational sustainable transport strategies implemented at the 2010 FIFA World Cup from the event goer perspective. An eclectic approach using social media, web resources, and quantitative-qualitative methods was used. Event goers reported using car more than public transport; many did not notice the environmental campaigns; hardly any post-event behavior changes related to travel were made. Event goer context provides insight on the effectiveness of structural and informational strategies and yields recommendations to improve outcomes for future events. iii Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31381 2012-05-27T00:00:00Z http://hdl.handle.net/1813/31382 Title: Human Ecological Dimensions Of Change In The Yukon River Basin:A Case Study Of The Koyukon Athabascan Village Of Ruby, Ak Authors: Wilson, Nicole Abstract: Although the three papers that comprise this thesis analyze distinct problems they are all rooted in the study of human ecology. To that end they are based on the same data set and share the same goals. Participatory research methods involving semi-structured interviews with twenty community experts, seasonal rounds and human ecological mapping are employed to analyze the subsistence livelihoods of the Koykon Athapaskan people of Ruby Village as a manifestation of human ecological relations. Chapter 1 examines the contribution of indigenous knowledge to understandings of hydrologic change in the Yukon River and its tributaries including observations of alterations in sediment and river ice regimes. Chapter 2 considers the ethical dimensions of adaptation and vulnerability to climate change in indigenous communities who are situated within a political context influenced by a history of colonization. Chapter 3 seeks to develop a concept of water sovereignty that addresses the complex socio-cultural and ecological relations between indigenous peoples and water. The integrated perspective provided by this thesis illustrates the connections between indigenous knowledge, subsistence livelihoods, socio-cultural and ecological relations to water and the assertion of sovereignty in the face of global change. Sun, 27 May 2012 00:00:00 GMT http://hdl.handle.net/1813/31382 2012-05-27T00:00:00Z