VictorJuiz/thesis huggingface dataset:
Durability and crash recovery in distributed in-memory storage systems [electronic resource]

This dissertation presents fast crash recovery for the RAMCloud distributed in-memory data center storage system. RAMCloud is designed to operate on thousands or tens-of-thousands of machines, and it stores all data in DRAM. Rather than replicating in DRAM for redundancy, it provides inexpensive durability and availability by recovering quickly after server crashes. Overall, its goal is to reconstitute the entire DRAM contents of a server and to restore full performance to the cluster in 1 to 2 seconds after failures. Consequently, RAMCloud provides continuous availability by recovering from failures so quickly that applications never notice failures. To achieve this, RAMCloud scatters backup data across thousands of disks, and it harnesses hundreds of servers in parallel to reconstruct lost data. The system uses a decentralized log-structured approach for all of its data, in DRAM as well as on disk; this provides high performance both during normal operation and during recovery. RAMCloud employs randomized techniques at several key points to balance load and to manage the system in a scalable and decentralized fashion. In an 80-node cluster, RAMCloud recovers 40 GB of data from a failed server in 1.86 seconds, and the approach scales to recover larger servers in the same period as cluster size scales.

Advisor: Ousterhout John K. primary advisor. Thesis advisor
Mazières David (David Folkman)
Rosenblum Mendel advisor. Thesis advisor
Dynamic asset allocation using adaptive particle filters [electronic resource]

Asset allocation is one of the most important problems in practical investment management and also plays a central role in financial economics. This study is devoted to an econometric treatment of asset allocation problems. We propose a very general procedure for dynamic asset allocation by using adaptive particle filters. It represents an advance over the traditional asset allocation because it incorporates jumps in mean returns and volatilities when using historical data. An advantage of our procedure is that it is very general and independent from any specific utilities. The empirical study shows our procedure indeed outperforms traditionally methods. The theoretical contribution of our paper is that we propose a general methodology which can accommodate lots of asset allocation problems. The methodology is easy to implement and simple to apply many models which are popular in returns modelling and asset allocation. It also inherits all the advantages of many variants of particle filtering approach. In fact, we provide a powerful tool for the researchers in finance area to solve the problems mentioned above. The empirical contribution is that we first apply our approach to the double-jump model. Based on S& P 500 data from 1996 to 2011, we find variations in posterior distributions of parameters. Our algorithm can quickly adapt to the new information and update the values. Next, we apply our framework to Log and Power utility. In general, we observe the same pattern for both cases: higher cumulative excess returns and larger CER for SVCJ model than SV model with same framework, higher cumulative excess returns and larger CER for our sequential strategy than others with same model.

Keywords: Management Science and Engineering.
Advisor: Lai T. L. primary advisor. Thesis advisor
Luenberger David G.
Primbs James advisor. Thesis advisor
A dynamic attenuator for computed tomography [electronic resource]

The utilization of x-ray computed tomography (CT) has increased dramatically in recent decades. While extremely useful, a major drawback of CT scans is their use of ionizing radiation. Today, one quarter of the radiation dose received by the U.S. population can be attributed to CT scans. We present the use of a dynamic attenuator which is capable of personalizing the radiation usage in the scan. This attenuator is inspired by a stationary-source, inverse geometry CT scanner, which is an architecture with several advantages but which is also very complex. The dynamic attenuator consists of a series of movable wedges which together produce a time-varying, piecewise-linear thickness profile. In simulations, this attenuator reduces dose by 30% in nontargeted scans and 50% in targeted scans without increasing peak noise. On many datasets, this attenuator can also achieve order-of-magnitude dynamic range reductions, which may aid in the adoption of photon-counting detectors, a separate technology which may provide additional dose reductions. We show that most of these dose reduction benefits can be achieved using a real-time control algorithm to position the wedges dynamically during the scan. Additionally, we have developed a framework for optimizing the control of a broad range of dynamic attenuators. A prototype system suggests that the level of artifacts produced by the wedge transitions is within the range of tens of Hounsfield units, although further refinements are expected to reduce artifacts. Based on these positive results, we believe that this dynamic, piecewise-linear attenuator is a practical and effective option for CT.

Keywords: Electrical Engineering.
Advisor: Pelc Norbert J. primary advisor. Thesis advisor
Fleischmann Dominik advisor. Thesis advisor
Nishimura Dwight George advisor. Thesis advisor
Dynamic portfolio execution [electronic resource]

As financial markets have become increasingly complex, the need to understand price dynamics at the microstructure level has become vital for market participants. Over the past decade, highly sophisticated ``high-frequency'' trading firms have emerged and have come to dominate equity markets and other asset classes, controlling anywhere between 50\%-90\% of the average traded volume on any given day. These sophisticated players utilize price and supply/demand dynamics in limit order markets to make trading decisions and provide liquidity at the micro-second level. In this environment, the optimal management of execution costs and control of price impact is of central importance to market participants, including portfolio managers for pension and mutual funds, hedge funds, market markers, etc. This thesis analyzes the optimal execution problem of a portfolio manager trading multiple assets in a limit order book environment. In addition to the consideration of liquidity and risk of each individual asset, we have to consider cross-asset interactions in these two dimensions, which are challenging to address. Focusing on the market microstructure, we develop a tractable order book model to capture the supply/demand dynamics in a multi-asset setting. The results suggest that cross-asset risk and liquidity considerations are of critical importance in constructing the optimal execution policies. Even when the goal is to trade a single asset, its optimal execution may involve transitory trades in other assets. In general, optimally managing the risk of the portfolio during the execution process influences the synchronization of trading in different assets. Moreover, correlations in the liquidity across assets lead to complex patterns in the optimal execution policies. In particular, we highlight cases where aggregate costs can be reduced by temporarily overshooting one's target portfolio.

Keywords: Management Science and Engineering.
Advisor: Giesecke Kay primary advisor. Thesis advisor
Infanger Gerd
Weyant John P. (John Peter) advisor. Thesis advisor
Dynamic procedure aids [electronic resource] : increasing access, assimilation, acceptance, and attention in crisis response and high-reliability domains

Many information-rich domains, from aviation to crisis response, require accurate responses under extreme time constraints. Paper checklists have been shown to improve important outcome measures. While these paper checklists are valuable, they are static, slow to access, and show both too much and too little information. Little is known about how to design checklists well, especially new forms of computer-aided checklists; experts produce most existing designs in an ad-hoc manner. In response, we introduce the Dynamic Procedure aids approach. Dynamic Procedure aids address four key problems in checklist usage: ready access to the aids, rapid assimilation of their content, professional acceptance of their use in medical procedures, and the limited attention available to their users. This design solution arose through a multi-year participation in medical crisis response training featuring realistic team simulations. A study compared Dynamic Procedure aids, paper aids, and no aid conditions, finding that participants with Dynamic Procedure aids performed significantly better than with paper aids or no aid. This study introduces the Narrative Simulation paradigm for comparatively assessing expert procedural performance through a score-and-correct approach Next, this thesis compares alternative checklist design proposals, distills effective design patterns, and shows that designing checklists with these features improves performance. A two-part experiment with medical participants was conducted in a laboratory with an eye-tracker. The first part compared time performance, eye-traces, and memory retention for five alternative checklist designs. From the results and design patterns, we distilled three key design principles to support rapid reading and instantiated them in a new design style. The second part compared the original designs to this redesigned style, called RapidRead. Applying these RapidRead principles reduced variance in response times, importantly minimizing the frequency of slow responses.

Advisor: Klemmer Scott primary advisor. Thesis advisor
Card Stuart K.
Chu Larry advisor. Thesis advisor
Dynamics of payoff and stimulus effects on decisions under time pressure [electronic resource] : combined behavioral, EEG and model-based analysis

It is well established that prior knowledge about payoff can bias decisions toward higher-paying alternatives. However, little is known about how payoff information affects the neural mechanism underlying these biased choices in humans. We address this question by recording electroencephalography (EEG) signals from 13 participants while they performed a two-alternative forced-choice task. On each trial, the participant judged whether a rectangle was shifted to the right or to the left of the fixation point and responded by squeezing the right- or left-hand dynamometer. Participants were cued about the payoff of each choice before stimulus onset and had to respond correctly before a short deadline (375-475 ms) to obtain the payoff. We show that payoff information influences participants' choices and response times: the frequency and speed of choices toward the higher-paying alternative increases. Moreover, we show that payoff bias is represented in the lateralized readiness potential (LRP), a response-related brain potential reflecting the preparation of motor activity in a specific hand. The representation of payoff bias in LRP has two components: a static component that shifts the LRP baseline toward the higher-paying alternative for hundreds of milliseconds before stimulus onset; and a dynamic component that causes an abrupt rise in LRP toward the higher-paying alternative after stimulus onset (but before stimulus information influences the decision). These components seem to reflect different processes; while the static component is not predictive of participants' choices or response times, the dynamic component predicts both. We also provide evidence showing that the static and dynamic LRP components propagate down to the muscles and can generate isometric forces measurable by dynamometers. Finally, drawing on both the LRP and motor responses, we present a new model for the effects of payoff information on the decision-making process. This model is based on a competition between a fast- guess process that is informed solely by payoff information and an evidence accumulation process that is informed by the sensory stimulus.

Keywords: Electrical Engineering.
Advisor: McClelland James L. primary advisor. Thesis advisor
Shenoy Krishna V. (Krishna Vaughn) primary advisor. Thesis advisor
Widrow Bernard
Dynamics of photo-excited bismuth [electronic resource]

The dynamics of photo-excited semi-metallic bismuth are determined by the strong interactions between the electronic and lattice degrees of freedom. In this thesis, I present results from ultrafast optical and x-ray experiments that explore the nonequilibrium behavior of photo-excited bismuth and help elucidate the coupling between these degrees of freedom. First of all, there has been sustained interest in the coupling between the photo-excited carriers and the zone-center longitudinal (A1g) optical phonon, as it relates directly to the magnitude of the Peierls distortion. Therefore, I have used optical pump-probe method to study the inverse Peierls distortion by directly looking at the A1g phonons under high carrier photo-excitation. In addition, the mechanism of ultrafast-excitation of A1g and Eg (transverse optical) phonon modes has been widely studied but not yet fully understood. Older models, including Impulsive Stimulated Raman Scattering (ISRS) the Displacive Excitation of Coherent Phonons (DECP) cannot perfectly explain the discrepancy of the data between spontaneous and time-resolved Raman scattering. We show that elements of both models are responsible for the excitation mechanism and attribute the weak coupling to the coherent Eg mode as due to the fragile Eg electronic coherence, and in the process of figuring out a novel way of probing extremely fast electron decoherence rates. Optical experiments are primarily sensitive to zone-center excitations. To further understand the non-zero momentum phonon behavior of photo-excited Bi as well as the ultrafast melting process, I have utilized time resolved x-ray diffuse scattering using different X-ray sources, including synchrotron generation and X-ray free electron lasers (FEL). I have observed thermally activated phonons whose lifetime is consistent with the thermal transport characteristic time. This time scale also dictates the epitaxial regrowth following laser induced melting. Non-equillibrium phonons, which live for hundreds of ps have also been observed, similar to our earlier observation in polar semiconductors. With better time resolution (~100 fs) from the Linac Coherent Light Source (LCLS), we were able to produce and observe large momentum squeezed phonons. Experimental results were consistent with simulation from first principle calculations throughout the Brillouin Zone (BZ). Ultrafast melting measurements with 100 fs resolution show results consistent with observations from earlier ultrafast electron diffraction. Moreover, they also show for the first time the highly anisotropic phonon softening, which lives for up to 1 ps, before the melting happens.

Keywords: Applied Physics.
Advisor: Reis David A.
Bucksbaum Philip H. advisor. Thesis advisor
Fisher Ian R. (Ian Randal) advisor. Thesis advisor
Dynamics of top eigenvalues of empirical covariance matrices of financial data [electronic resource]

Covariance matrices of financial data and their inverses play an important role in algorithmic portfolio optimization and risk management. For example, PCA (principal component analysis) based strategies in algorithmic portfolio trading, and Markowitz portfolio theory in risk control and portfolio construction. However, since the true covariance matrix is neither perfectly known nor constant in time, the dynamics of the empirical covariance covariances is of great importance, as the volatilities and correlations evolve with time. It is obviously too heavy to carry the whole empirical covariance matrices all the time, especially when they contain a lot of noise. As PCA strategies suggest, most of the meaningful economic information is contained in the large eigenvalues and eigenvectors of covariance matrices, especially, the largest eigenvalue and eigenvector correspond to a collective market mode. As also suggested in risk control, the largest eigenvalue and eigenvector represent the most risky direction in a financial context. The largest eigenvalue of the empirical covariance matrix and the corresponding eigenvector are of considerable importance and we want to analyze their stability over time and characterize their fluctuations. We thus study the dynamics of the top eigenvalues and eigenvectors, instead of the whole matrices. In the thesis, we use a one factor continuous time model and study the dynamics of the top eigenvalues of the empirical covariance matrices. We first model the dynamics of stock returns and construct the empirical covariance matrices through an exponential moving average of the returns. We then derive a stochastic differential equation for the deviation part of the empirical covariance matrix from the true covariance matrix. We also establish a weak convergence result for the top eigenvalue of the deviation matrix at the equilibrium level, and show that the dynamics of the top eigenvalues of the deviation matrices satisfies in probability a reflecting stochastic differential equation for large N (size of covariance matrix) and a large true top eigenvalue. Numerical results are presented at the end to validate our theoretical results.

Advisor: Papanicolaou George primary advisor. Thesis advisor
Giesecke Kay advisor. Thesis advisor
Glynn Peter W. advisor. Thesis advisor
The dynamics of translation initiation and elongation [electronic resource]

Translation is the final step that converts genetic information into proteins composed of amino acids using the ribosome-- a complex molecular machine that coordinates the kinetics, chemistry, and mechanics necessary to synthesize a polypeptide. Translation is highly dynamic with processes taking place on the microseconds to minutes timescales. Among the different techniques employed to probe the dynamics of translation, single-molecule fluorescence occupies a unique position, being able to track heterogeneous compositional and conformational changes occurring within tens of milliseconds to minutes. Leveraging several fluorescent signals, we probed the dynamics of translation initiation. Instead of a linear pathway, we observed several different pathways all leading to the formation of an elongation competent ribosome complex, with the flux through each modulated by initiation factors, tRNAs, and mRNA sequence. Next, we tracked how the aminoglycoside family of antibiotics inhibits ribosome and tRNA dynamics during peptide synthesis (elongation), concluding that their potency as bactericides stems from kinetically inhibiting elongation. Finally, we transitioned from model systems into observing elongation dynamics on a biologically functional protein stall sequence, SecM. Our results suggest that stalling the ribosome requires several precisely-timed peptide-ribosome interactions and that ribosomes stall in a distribution of locations on the SecM sequence. These results demonstrate the power of single-molecule fluorescence to monitor global translation dynamics, as well as highlighting the importance of the temporal dimension in forming a coherent and global mechanism for translation.

Keywords: Applied Physics.
Advisor: Doniach S. primary advisor. Thesis advisor
Puglisi Joseph D. primary advisor. Thesis advisor
Bryant Zev David advisor. Thesis advisor
Dysmorphic sovereignty [electronic resource] : colonial railroads, eminent domain, and the rule of law in British India, 1824-1857

This dissertation charts the origins of the law of expropriation, or eminent domain, in modern India, to shed historical light on the social conflicts and environmental risks that surround legalized mass dispossession and natural resource extraction there today. It locates the origins of the law in two moments in mid-nineteenth century colonial Bengal: the first, in the 1820s, when a modified version of British domestic expropriation law made its way into Bengal in response to ecological changes that had acted to constrict colonial expansion; and the second, in the late 1840s and early 1850s, when this law was revived and reshaped to meet the East Indian Railway's unprecedented demands for land. It ends with the passage of Act VI of 1857, wherein the Bengal law was generalized to create the first Land Acquisition Act for the whole of British India. The dissertation argues that although many of the mechanisms designed to protect landholders and justify infrastructure projects in Britain were stripped out of the law when it was filtered through the East India Company's uneven, or dysmorphic, conception of its sovereignty, that emphasized the state's prerogatives but downplayed its obligations, the colonial commitment to lawfulness, though sometimes only rhetorical, ensured that these distortions never constituted outright mishandling of the law. Although zamindars (landlords) were better compensated than raiyats (peasants), and Europeans were accorded substantial negotiated settlements but Indians generally had to accept official valuations, compensation was paid and petitions and other forms of supplication from Indians reporting on the indiscretions of railway engineers and contractors were entertained, if rarely acted upon.

Advisor: Roberts Richard L.
Kumar Aishwary advisor. Thesis advisor
Satia Priya advisor. Thesis advisor