VictorJuiz/thesis huggingface dataset:
Optimizing remote procedure calls in datacenters using hardware/software co-design

In this dissertation, we present the nanoPU, a new NIC-CPU co-design that provides ultra low and predictable remote procedure call (RPC) response time and thus accelerates datacenter applications. The nanoPU achieves its goal by providing a fast path between the network and applications. This fast path has the following three characteristics: (1) it moves key resource scheduling decisions from software to hardware (reliable network transport & congestion control, RPC load balancing across cores, thread scheduling) allowing them to operate much more efficiently, (2) it provides a path directly between the network and applications which bypasses the cache and memory hierarchy placing arriving messages directly into the CPU register file, and (3) it supports a unique thread scheduling feature to bound the tail response time experienced by certain high-priority applications. We built an FPGA prototype of the nanoPU fast path by modifying an open-source RISC-V CPU, and evaluated its performance using cycle-accurate simulations on AWS FPGAs. The wire-to-wire time for nanoPU to receive an incoming message and initiate transmission of a response (response time) is just 69ns, an order of magnitude quicker than the best-of-breed, low latency, commercial NICs. Our hardware implementation of the NDP transport protocol adds less than 10ns to the wire-to-wire response time. We demonstrate that the hardware thread scheduler is able to lower (and potentially bound) RPC tail response time by about 5x while enabling the system to sustain 20% higher load, relative to traditional thread scheduling techniques. Furthermore, the nanoPU's core selection policy in hardware is able to efficiently distribute RPCs across cores eliminating hot spots and reducing tail response time. We implement and evaluate a suite of applications on the nanoPU, including MICA, Raft, and set algebra for document retrieval

Keywords: Electrical Engineering.
Advisor: McKeown Nick
Brebner Gordon
Ousterhout John K.
Organizational learning and knowledge creation

How does invention happen? The initial step of organizational learning is knowledge creation. The foundational processes of knowledge creation are little understood. Eminent scholars of organizational learning have made calls for more "fine-grained" examinations of knowledge creation, agreeing that "more theoretical work is needed to further expand on processes through which new organizational knowledge emerges, " and that the knowledge creation process is the area that would "most benefit from more theorizing and empirical research...and is needed to round out our understanding of organizational learning"(Argote & Miron-Spektor, 2011; Tsoukas, 2009). To understand these processes, I embedded over two years with an engineering team that was seeking to invent the world's first 3D printed production car. Immersing in a group that was so explicitly tasked with invention was vital to answering these central questions. In this work, I seek to answer the following question: How do workers intentionally craft experiences through which knowledge is created, particularly in situations where knowledge creation is the central activity of the workers' efforts? I answer this question across three papers, introducing the concept of Wargaming and describing the typology of Learning Episodes as well as the three Experiential Approaches that knowledge workers use to direct their learning activities

Advisor: Fischer Martin
Bednar Jeff 
Hancock Jeffrey
Organizational Structure and Decision-Making in Corporate Venture Capital

This paper studies corporate venture capital (CVC) units of large US corporations to learn how they make decisions across several areas: internal organization of CVC units, relationships with parent companies, CVC unit objectives, investment process and approval, deal structure, relationship with portfolio companies, compensation, and composition of CVC teams. The study is conducted by interviewing senior team members of seventy-four CVC units, representing 78% of the active CVC units of companies in the S&P 500 index. CVC units are organized in significantly more diverse ways than institutional VC firms. Unlike institutional VC firms, most CVC units do not manage committed venture funds, but instead invest from the balance sheets of their parent companies. Investment committees, in which parent company executives play a pivotal role in approving individual decisions, are common. Many corporate venture capitalists (CVCs) believe executives at their parent companies do not understand the norms of the venture space. The demographic composition of senior team members at CVC units is very different than that of their counterparts at institutional VC firms. The results raise a number of issues about the economic role of CVC units in corporate innovation.

Keywords: Department of Economics
corporate venture capital
corporate innovation
venture capital
deal structure
portfolio companies
balance sheet investing
Thesis
Organized grouping mediates the environmental interactions of social squids

A surge of recent research suggests that current and future shifts in marine species' distributions are ultimately driven by physiological responses to environmental variation. These observations and predictions are important because changes in species' distributions cause ecological change through community reorganization. However, they do not necessarily capture the full effects of behavioral adaptations on species' ecologies. Behaviors mediate the response of an organism's physiological processes to environmental variation, and can profoundly affect individual fitness, and thus population demography and community dynamics, under environmental variability. One of the most conspicuous and taxonomically widespread behaviors of animal life in the ocean is social behavior, or aggregation behavior related to inter-individual cohesion among conspecifics. Social interactions can buffer physiological responses to stressful conditions, shape behavioral patterns of individuals, and drive individual decision-making, with ecological and evolutionary consequences. While these impacts are becoming increasingly apparent in other systems, to date very few investigations explicitly consider the mechanisms and physiological effects of social behavior in the ocean. Squid, a predominantly predatory clade of highly motile molluscs, are a particularly compelling group of marine animals with which to develop such understanding. Many squids are social, occur across a range of environmental conditions, possess activity-limiting physiological constraints, visually communicate with complex pigmentation patterning, and demonstrate considerable ecological and life history flexibility. In this dissertation, I examine the patterns, mechanisms, and physiological effects of social behavior in open ocean squids, and how physiological sensitivities to environmental variability in squids can lead to new ecological interactions of potential consequence. Joining an emerging body of research, my dissertation work shows how social behaviors that confer emergent benefits are adapted to environmental gradients in the ocean. It also highlights the importance of social behavior in understanding habitat selection and the corresponding ecological changes in the ocean. As empirical and theoretical research continues to explore how social behavior shapes such ecological patterns, the understanding we develop will facilitate more sustainable harvest, more effective conservation, and more accurate predications under global change

Keywords: Biology.
Advisor: Denny Mark W.
Goldbogen Jeremy
Robison Bruce H.
Somero George N.
Out of many, one : distilling the physics of behavior across scales for an animal without a brain

The physics of behavior is a rapidly growing discipline which seeks simple descriptions of an animal's behavior in the language of low dimensional dynamical systems constructed from data driven approaches. Despite rapid progress, we still do not generally understand the rules which shape these emergent behavioral manifolds in the face of complicated neuro-construction --- even in the simplest of animals. In this work, we introduce a non-neuromuscular model system which is complex enough to teach us something new but also simple enough for us to understand deeply: Trichoplax Adhaerens. Through the study of this experimental model, we stand to learn more about how the animal kingdom builds successful animals from millions of specialized cells. Central to this work, we report five experimental discoveries: 1. a broad crossover regime between swimming and stalling in ciliary oscillators interacting with a surface via an adhesion energy which we call 'ciliary walking', 2. sub-second ciliary reorientations can self-organize into a collective phenomena which we call 'ciliary flocking', 3. the dominant behavioral manifold of ciliary flocking is shaped by a stable emergent coherent structure topologically classified as a +1 defect, 4. the top layer of the organism exhibits ultrafast cellular contractions which can reduce the cellular cross section by 50\% in a single second generating nonlinear contraction waves, and 5. the bottom tissue of the organism mixes different cell types to tune the material response introducing the concept of an 'epithelial alloy'. We complement these discoveries with a suite of models by construction at every scale of the problem from organelle to organism. Through a careful study of these frameworks of many-body dynamical systems driven out-of-equilibrium by distributed activity, we report an array of conceptual tools (excitable mechanics of spatio-temporal fields, active-elastic parametric resonance, and an inverse energy cascade) which enable these non-neuromuscular animals to perform agile locomotion across millions of cells without a central controller. We hope these results can inspire future approaches to technologies which exploit distributed agency such as swarm robotics and edge computing. Looking ahead, we suggest that the simple perception-actions cycles of this organism provide a promising opportunity to study the morphological computation embedded in this physical reservoir of high-dimensional, nonlinear tissue dynamics

Keywords: Applied Physics.
Advisor: Prakash Manu
Bryant Zev David
Ganguli Surya
Over-the-air statistical estimation

The data fueling today's rise in machine learning is often generated by devices at the edge of a network, like sensors or mobile devices. To use all this data to train a common model, devices need to communicate something about their own data to a central server. But physical communication channels have limits, and these constraints are increasingly becoming the bottleneck in distributed and federated learning systems. Can we improve such learning algorithms by explicitly incorporating the physical communication layer into their design? We explore this question using a new framework that draws on wireless communication theory and statistical estimation. We propose "analog" estimation schemes that exploit the superposition inherent in multiple-access wireless networks, and analyze their performance. We then consider fundamental limits on how well "digital" schemes, which separate the communication and estimation stages, can possibly do. Comparing the two under several statistical models shows that the analog approach can yield drastic improvements in estimation error over the digital one. We also derive lower bounds for analog schemes that are within a logarithmic factor of our achievability results, and we present experimental results showing that these ideas can translate to performance gains in a federated machine learning context

Keywords: Electrical Engineering.
Advisor: Özgür Ayfer
Van Roy Benjamin
Weissman Tsachy
Parasitic intimacies : life, love, and labor in post-socialist Central Asia

This dissertation considers how the lives and labors of a diverse and disparate set of Central Asian women might help us reimagine economic possibilities and socio-political futures in a time of precarious employment and diminished social security. Based on over two years of research in Kyrgyzstan and across its borders, it narrates the exploits and travails of entrepreneurial traders traveling to China and Turkey, rural migrants and undocumented women in the sex trade, and marginalized drug addicts as they seek care from service providers and public health programs. These diverse groups were once criminalized as "social parasites" in the Soviet Union. Today, despite the residues of stigma, their activities are the mainspring of livelihoods. By bringing together both economic and medical discourses, my dissertation analyzes how the figure of the "parasite"—those classes of people who are not viewed as productive members of society—carries gendered and racial connotations. It argues that so-called "unproductive" activities and relations of dependence are, in fact, forms of generative, relational work that shape local imaginaries of care, as well as transnational flows of people, goods, and wealth

Keywords: Anthropology.
Advisor: Yanagisako Sylvia Junko
Ferguson James
Grant Bruce
Reeves Madeleine
Thiranagama Sharika
Particle resolved simulations of particle-flow interactions in fluidized beds to optimize design and operation of domestic wastewater treatment systems

Recently, the Staged Anaerobic Fluidized-bed Membrane Bioreactor (SAF-MBR), which consists of an anaerobic fluidized-bed reactor (AFBR) and a particle-sparged membrane bioreactor (P-MBR), has been developed to reduce the energy intensity of domestic wastewater treatment by using anaerobic microorganisms that convert organics into methane in the absence of aeration. While this has the potential to transform domestic wastewater treatment into an energy positive process, the moving particles in the SAF-MBR induce hydrodynamic processes related to flow-particle and particle-particle interactions that are poorly understood. With a better understanding of hydrodynamics, better design and operational practices can be developed. In this dissertation, a collocated particle resolved simulation (PRS) using the immersed boundary method (IBM) is developed to accurately quantify the fluid-particle and particle-particle interactions in a fluidized-bed reactor. This dissertation first investigates the effect of particle Reynolds number which is essentially a nondimensional flow rate that controls the bed expansion. Results imply the existence of an intermediate particle Reynolds number regime at which the combined effect of flow and collisions is optimal and both mixing in the AFBR and membrane scouring in the P-MBR are expected to be maximized. While the Reynolds number is a critical parameter, the design of fluidized beds depends critically on the Archimedes number that combines the effect of particle and fluid properties. Simulation results reveal that particles with Archimedes number greater than roughly 1000 should be used to avoid flow short-circuiting due to clusters in the AFBR and reduced membrane scouring due to ineffective collisions in the P-MBR. In industrial applications, fluidized beds typically contain particles of different sizes that tend to segregate into layers in which the particle size increases moving upward. Our simulations reveal that segregated layers behave identically as they would in their corresponding monodispersed fluidized bed layers. However, the transition region between the two segregated layers cannot be described as a simple superposition of the two segregated layers

Advisor: Criddle Craig 
Fringer Oliver B. (Oliver Bartlett)
Hickey Robert F.
McCarty Perry L.
Partisan polarization and international politics

This dissertation explores the relationship between partisan polarization and international politics. The project asks two questions. The primary question is: How does polarization affect the way democracies behave in international politics? Relative to non-democracies, democracies are generally better at keeping foreign policy consistent despite regular leadership turnover (stability advantage), credibly signaling information to adversaries (credibility advantage), and maintaining their international commitments (reliability advantage). I argue that extreme polarization undermines these "democratic advantages" by eroding the vertical and horizontal constraints on political power that confer them. I build evidence for this argument by leveraging new cross-national data on foreign policy positions of executives in 55 democratic countries from 1945-2015. I then focus on how polarization affects contemporary American foreign policy. Drawing on three original survey experiments, analyses of descriptive data on the behavior of political officials, and a series of elite interviews conducted in Washington, D.C., I show that growing polarization makes the United States a less credible adversary and less reliable ally. The secondary question this dissertation asks is: How does a state's security environment affect domestic polarization? A common explanation for the increasing polarization in contemporary American foreign policy is the absence of external threat. Using three methods—computational text analysis of congressional speeches, examination of historic public opinion polls, and a survey experiment about threats from a rival foreign power—I find that the external threat hypothesis has limited ability to explain either polarization in US foreign policy or affective polarization among the American public. Instead, responses to external threats reflect the domestic political environment in which they are introduced. Overall, this dissertation project emphasizes that partisan polarization is an important and under-explored source of variation in democratic foreign policymaking. I argue that we have little evidence that international threats have major impacts on domestic polarization. However, polarization over foreign affairs has important—and largely negative—consequences for the stability, credibility, and reliability of democratic states

Keywords: Political Science.
Advisor: Schultz Kenneth A.
Tomz Michael
Weinstein Jeremy M.
Past and future changes in river temperatures and nitrogen export

Climate change poses a growing threat to freshwater ecosystems and water quality. This dissertation examines the relationship between changes in climate and two key water quality parameters: the transport of nitrogen within rivers, referred to as nitrogen loading, and river temperature. Chapter 2 examines how changes in air temperature and precipitation influence historical trends in U.S. nitrogen loading. I find that annual precipitation, extreme springtime precipitation, and springtime temperature are key drivers of trends in historical loading. The Appendix addresses time scales for recovery of Gulf of Mexico nitrogen loading, challenging an assertion made in a previous study that achieving nitrogen reduction goals will inevitably take decades. Chapter 3 quantifies how river temperature extremes and variability have changed in recent decades. I find that the majority of rivers have already experienced warming of hot extremes and a significant change in variability. Chapter 4 explores the sensitivity of river heatwaves— periods of persistent, extreme river temperature—to future climate change using a neural network and global climate models. I find that river heatwaves are projected to increase significantly in frequency, duration, and severity in response to climate change, including a tripling of heatwave days by 2050 under a high carbon emissions scenario. Overall, this dissertation reveals that substantial changes in nitrogen loading and river temperatures are already underway in rivers across the U.S. Increases in river temperature extremes and ensuing ecological and socioeconomic impacts may also become critically severe in the coming decades

Keywords: Environmental Earth System Science.
Advisor: Boehm Alexandria
Jackson Robert W. (Robert Wilson)
Konings Alexandra
Michalak Anna M.
Past present : the literature of human rights in postdictatorial Brazil, Argentina and Chile

From an interdisciplinary perspective situated across memory studies, law, and literature, I examine what I define as the literature of human rights in contemporary Latin America: legal and literary narratives with a truth-seeking function vis-à-vis the past that have the potential to impact the present. I analyze narratives from postdictatorial Brazil, Chile, and Argentina, namely truth and reconciliation commission reports and the following fictional narratives: Julián Fuks's A resistência (2016), Alia Trabucco Zerán's La resta (2014), and Selva Almada's Chicas muertas (2015). In each chapter, I interrogate the relevance of concepts such as "truth" and "trust" to memory studies and jurisprudence, as well as their impact on the development of public awareness and discussion—the necessary preconditions for democracy and political change. Considering legal and literary narratives to be part of the activity frameworks that drive social and political change, I explore literature's relevance to human rights and its potential to uncover and examine issues, subjects, and geographic regions that legal systems might exclude

Keywords: Iberian and Latin American Cultures.
Advisor: Hoyos Ayala Héctor
Barletta Vincent 
Briceño Ximena
Meyler Bernadette
Patterns in fungal community composition and decomposition

Fungi play important roles in terrestrial ecosystems. Here, I perform four investigations (chapters two, three, four, and five) into variation in fungal communities and examine how this variation affects processes controlled by fungi. In chapter two, I use a natural dispersal gradient to evaluate whether a mechanism proposed to support diversity in plant communities whereby the dispersal ability of a species trades off with its competitive strength is applicable to communities of root-symbiotic fungi. I determine that such a tradeoff exists and maintains fungal diversity in my study system. In chapter three, I compare the effects of wildfire on soil fungal communities across two different ecosystem types, finding that ecosystems which are adapted to regular fire exhibit less change in their fungal communities when burned than other ecosystems. In chapter four, I combine modelling and meta-analysis to determine the effects of competition between different types of fungi on litter decomposition. I find that fungal competition has context-specific effects, with decreases in decomposition rate occurring only where recalcitrant litter chemistry allows root-symbiotic fungi to prevail against free-living decomposer fungi. In chapter five, I show that communities of wood-decay fungi have multiple qualitatively different links with wood decomposition rate, the relative strength of which are subject to the spatial scale at which systems are examined

Keywords: Biology.
Advisor: Peay Kabir
Fukami Tadashi
Jackson Rob
Vitousek Peter Morrison