VictorJuiz/thesis huggingface dataset:
Bobcat distribution and abundance at Jasper Ridge Biological Preserve in Northern California
Keywords: Dirzo, Rodolfo
Biology, 2015
Department of Biology
Stanford
Ecology and Evolution
ecology
animal behavior
bobcat
lynx rufus
Jasper Ridge Biological Preserve
Thesis

Conservation and land management decisions are often based on an understanding of the distribution, abundance, and habitat requirements of wildlife. In this study, I examined the spatial distribution and abundance of the bobcat (Lynx rufus), a mid-sized predator, at Jasper Ridge Biological Preserve (JRBP) using camera traps. The initial camera trap survey was conducted from 2006 to 2008. I conducted another survey from 2014 to 2015. The comparison suggests that the relative abundance of bobcats has decreased substantially from the 2006-2008 survey to the 2014-2015 survey. This may be due to several factors, including the recent drought, increased human activity and construction, the incidence of notoedric mange, and increased puma abundance. The drought could indirectly affect bobcats by altering vegetation and reducing prey abundance. In both surveys, bobcats and their prey species exhibited crepuscular activity patterns, and bobcat occurrences did not vary by season. The distribution of bobcats was not predicted by canopy type or vegetation cover. As expected, bobcat abundance was positively correlated with prey abundance across both surveys. Human activity was measured only in the 2014 to 2015 survey and did not affect bobcat distribution, likely due to the temporal separation between the diurnal activity of humans and the crepuscular activity of bobcats. Unexpectedly, in the most recent survey, they were most abundant in locations with relatively high abundance of puma. In addition, bobcats and puma had a high degree of diel overlap. This could indicate that puma contribute to the decreased abundance of bobcats by competition or predation. Further research on the impacts of human activity, the recent drought, notoedric mange, and increased puma abundance are necessary, as well as continued camera trap monitoring of bobcats.
Books vs. Bombs: Reading Objects in Michael Ondaatje's The English Patient
Keywords:  Department of English
Michael Ondaatje
The English Patient
postcolonial literature
postmodern literature
identity
ideology
thing theory
objects
books
bombs
World War II
Thesis

This thesis uses objects to understand Michael Ondaatje's treatment of his characters' identities and ideologies in the 1992 novel The English Patient. An analysis of books and bombs reveals how these objects' physical and representational qualities shape the characters who interact with them, pointing to a relational model of identity.
Bounding Creativity: Explicit and Implicit Constraints in the Design Process Yield More Novel Results
Keywords: creativity
design process
constraints
design fixation
Thesis

We present a series of human creativity experiments that examined the effects of two styles of constraints — external task requirements imposed by others and internal fixation on values or ideas that are self­-imposed. Counter to prevailing wisdom that late changes to project requirements reduce outcome quality and that design fixation reduces novel concept exploration, we find that both produce more novel results in creative processes. Participants were asked to create static graphic advertisements. The first study introduced participants to a narrowed constraint either at the beginning, middle, or end of the prototyping process. The narrow constraint addressed goal and task requirements by specifying the target audience and ad size. Late constraints were shown to yield more novel results. If explicit constraints can produce more novel constraints, might implicit constraints do the same? The second study examined the effect of fixation on creativity. Higher fixation (induced via preference construction) yielded more novel results. However, this effect reversed when participants were also given late constraints. Designers may not welcome late constraints or design fixation; however, our results showed that boundaries around a creative problem, whether they be imposed by others or oneself, may further optimize ideation and design methodologies.
Building bigness [electronic resource] : religious practice and social support in rural South India
Keywords: Anthropology.

This dissertation investigates the ways in which people in two villages in Tamil Nadu, India use religious practice to gain insight into the underlying character and intentions of others. More broadly, it is an evaluation of the social causes and consequences of religious action and a test of the "costly signaling theory of religion." In these villages, residents sometimes undertake what can be quite dramatic religious acts: walking on a bed of hot coals, piercing their cheeks with spears, sacrificing animals, and getting possessed. They also pray in their homes, worship at temples, and attend church services. Drawing from survey data providing reputational evaluations and social support network data, this dissertation elucidates the social consequences of religious practice, both for the individuals who undertake these ritual acts, and for the communities of which they are a part. The data show that those who are involved, and involved in costlier ways, in the religious life of the village are not only seen as more devout, but also seen as having a wider suite of prosocial traits. In accordance with those reputational qualities, villagers are more likely to go to a person for support of any kind, if he/she is involved in the religious life of the village. Greater religiosity does not just burden a person with requests for assistance: such individuals are themselves better able to access the social support so necessary to one's livelihood. Many of these supportive bonds are between religious co-participants: shared participation in rituals increases the likelihood of a support tie between individuals, and, at the group structural level, results in more dense and reciprocal ties between participants. These results provide broad support for the costly signaling theory of religion, but also suggest more complex relationships. The scale of the audience (which make some acts "dramatic" and some "subtle") and the diverse types of "cost" (including not only what is endured in carrying out a ritual act, but also the external threats of gossip and censure) mean that there is quite a range of religious acts to be undertaken. Importantly, villagers are differentially able to undertake those various acts because of their relative social positions.
Building the nation, binding the state [electronic resource] : nationalism, insecurity, and ethnic tolerance in Kyrgyzstan
Keywords: Political Science.

Following an outbreak of ethnic violence in 2010, the Kyrgyz Republic embarked on an ambitious program of promoting a Kyrgyz-centric form of national identity. The international community reacted with alarm, worried that the "Kyrgyz-i cation" of the country would lead alienate minorities and encourage more violence from the Kyrgyz, while the Kyrgyzstani government argued that Kyrgyz culture was itself under threat, and that solidifying its position within Kyrgyzstan would ultimately reduce tensions. These arguments reflect a wider and more abstract debate within the political science literature about the dangers and benefits of nationalism, the challenges of building national identity in a multi-ethnic context, and the relationship between nationalism and ethnic violence. Using a combination of interviews, ethnography, and survey experiments, I find that exposure to nationalist propaganda reduces feelings of insecurity on the part of ethnic Kyrgyz, which in turn reduces their propensity to view members of minority groups as threats. This, in turn, makes ethnic violence less likely. Minority group members, in turn, are willing to tolerate Kyrgyz culture, language, and history receiving a certain amount of privilege within the Kyrgyz Republic. However, the content of nationalist propaganda can vary considerably, and in cases in which it advocates hostility towards minorities it can do great harm.
Building the Neural Circuit: Neuronal Extracellular Matrix Components Required for Proper Synapse Formation and Morphology
Keywords:  Department of Biology
Stanford University
Department of Biology
Department of Pathology
Howard Hughes Medical Institute
developmental neurobiology
synapse formation
neuronal extracellular matrix
C. elegans
genetic screen
RNA interference
pathway mapping
Thesis

Despite synapse formation’s central role in neurological development, its underlying mechanisms still remain to be fully characterized. Until recent years, molecular studies of this process have largely ignored the neuronal extracellular matrix (ECM), as well as the basement membrane proteins that define the extent and functionality of the region. However, due to their localization at neuronal cell surfaces, basement membrane proteins are now increasingly being identified as prospective mediators of the guidance mechanisms necessary for proper circuit assembly.
This investigation further develops an emerging role for the neuronal ECM in synapse formation. First, we describe a novel model of defective synapse formation in C. elegans, characterized by a loss-of-function allele for GON-1, a basement membrane protein (of the ADAMTS metalloprotease family) with putative ECM remodeling functions. Unbiased genetic screens carried out on this gon-1-/- background revealed neuronal ECM proteins with both enhancing and suppressing effects on the synapse-formation-defective phenotype. These modifier screen hits were then assayed for reproducible exacerbation or amelioration of this phenotype via both genetic knockout and translational inhibition experiments, implicating several in a cohesive, ECM-specific synapse development pathway centered on the GON-1 protein.
Ultimately, this pathway must be characterized if neurobiologists are to understand nervous system development on a cellular level. In the meantime, these mechanisms are expected to provide vital insight into neurodevelopmental disorders (with particular optimism regarding autism spectrum disorders) and the demands of viable nerve tissue repair strategies, which will have enormous clinical significance in the coming decades.
Buy it Now: An Analysis of the Effects of Buy Prices in Auction Listings
Keywords:  Department of Economics
Internet auctions
online markets
anchoring
bidder behavior
Stanford Department of Economics
Thesis

The rise of online auction platforms in the past decade has presented a wealth of new data and puzzling effects to researchers. New listing strategies and parameters created to give both sellers and bidder flexibility have also led the way for new types of listings. This paper explores the potential behavioral effects of simultaneously listing an auction with a fixed price option using data from eBay. It looks specifically at how the fixed price option—known as the Buy it Now (BIN) option on eBay—affects bidder behavior and how this translates into seller outcomes. It looks at (1) whether or not the BIN price has an effect on the final sale price of an auction, and (2) whether this effect can be attributed to anchoring. Two main results arise from this study. The first is that BIN prices have a positive effect on expected seller revenue, especially when the BIN price is more persistent and when the item is more unique. In the case of the former, this is caused by the higher probability of BIN exercise and in the later, this is caused in part by the pure existence of the BIN price. Second, bids anchor to the BIN price, which can help explain the mechanism through which final sale prices rise with the BIN price. This result is significant because in contrast to previous literature, it suggests that sellers might still benefit by setting a BIN option with effectively zero probability of exercise.
Buyer strategies to maintain suppliers in development-intensive supply chains [electronic resource]
Keywords: Management Science and Engineering.

The semiconductor equipment, aerospace, and defense industries are becoming ever more consolidated in today's globalized industrial scene: a few market-dominating buyers work with an ever-decreasing number of major suppliers for reasons including industry maturity, demand consolidation, and increasing capital intensity. All giant buyers such as Intel, Apple, Boeing, and the U.S. Department of Defense not only have to obtain critical equipment from a single supplier or a small number of suppliers but are also concerned about procurement decisions that may ultimately affect suppliers' incentives to perform R& D and stay in business. My dissertation research formulates and analyzes stylized game-theoretic models composed of two suppliers of different priority tiers, a preferred focal supplier and a partner supplier less preferred by the buyer. These two suppliers develop a product subject to financial pressures, and supply a powerful buyer who can influence their finances as well as development capabilities. I demonstrate the viability of several strategies for the buyer: (1) egalitarian value allocation schemes in the face of relationship decline, (2) commitment to develop partner suppliers against increased supplier asymmetry, and (3) commitment to competitive price targets and value-sharing to induce supplier collaboration.
BUZZ: The Impact of Positive User Sentiment on Startup Company Valuations in the USA
Keywords:  Department of Economics
Stanford University
Department of Economics
startup
consumer technology
venture capital
financial valuation
user acquisition
stages of funding
Crunchbase
Stanford University
Department of Economics
Thesis

In this paper, I exploit organic user buzz to reveal that investors view
positive user data as a proxy for future user acquisition and company growth.
After conducting venture capital investment analysis, I show that companies
that experience higher degrees of market excitement receive higher levels of
interest from investors. The more user buzz a startup receives, the more
likely it is that it will, first, participate in an additional funding round, and,
second, receive a higher valuation in the next funding cycle. My analysis also
finds that venture capitalists are not yet adept at predicting market
excitement for a particular product at earlier funding stages. Instead, they
are more likely to apply a “spray and pray” early-stage investing approach.
Can nonprofits lead a movement for economic justice? [electronic resource]
Keywords: Sociology.

The purpose of this dissertation is to use sociological theory to investigate how we might get a movement for economic justice in the United States. I argue that the participation of low-income and poor people is crucial to securing good solutions to poverty. I then suggest that participation could begin in the very civic institutions that make it their mission to alleviate poverty: nonprofit charities. After describing how I collected and analyzed my data and providing context in Chapter 2, the bulk of the dissertation addresses three questions related to that participation. First, how do low-income people define poverty and what does this imply about the types of solutions they might want to participate in? Second, what kinds of benefits do they reap from participation? And, third, what kinds of challenges do organizations face when they try to incorporate more participatory programs -- particularly community organizing -- and how can these challenges be overcome?.
Can't we all just get along? Native-born Americans' perspectives on race and immigration [electronic resource]
Keywords: Sociology.

How do native-born Americans understand and react to immigration-driven diversity? My dissertation explores this question in three distinct empirical projects. Using a combination of original survey experiments and longitudinal (panel) survey data, I examine the causal effects of a growing, racially diverse immigrant population on the attitudes and behaviors of native-born Americans. In the first paper I find that even as immigrants achieve social mobility, they are unable to break down the symbolic racial boundaries that White Americans believe separate themselves from others. In the second paper I find that immigration is leading to divergent views of racial social distance among native-born White, Black, and Latino Americans. However, identifying the precise mechanisms through which growing immigrant communities produce causal effects on Americans' attitudes and behaviors is more complicated than previous research would suggest. The final paper in my dissertation begins to tackle this question using longitudinal survey data, and finds that 'White flight' from growing local immigrant communities, rather than attitude change, explains the association between the size of local immigrant populations and public opinion on immigration. All together, these three papers suggest that while immigration-driven change is leading to some signs of racial progress, overwhelmingly White Americans continue to view society through highly racialized lenses which exclude most immigrant-origin groups.
Capacitive micromachined ultrasonic transducers (CMUTs) for therapeutic applications [electronic resource]
Keywords: Electrical Engineering.

High-intensity focused ultrasound (HIFU) is a noninvasive method to treat a variety of diseases. Most of the HIFU machines in clinic typically consist of a piezoelectric transducer array and an imaging system for temperature monitoring and anatomical location guidance. One of the limitations of piezoelectric transducers is self-heating, which requires cooling systems to protect both transducers and patients. Capacitive micromachined ultrasonic transducers (CMUTs) are another type of transducers fabricated with silicon micromachining. CMUTs are promising candidates as therapeutic transducers, as they experience a lot less self-heating compared to piezoelectric transducers. This dissertation mainly focuses on describing the design, simulation, fabrication, characterization, and experimental results of CMUTs for HIFU applications. Single-element transducers are fabricated using local oxidation of silicon (LOCOS)-wafer-bonding process. The measurement part compares the self-heating of a PZT and a CMUT, and discusses the charging issue of CMUTs. Geometric focusing using multiple single-element CMUTs is also demonstrated. The fabrication of 1-D CMUT arrays to enhance the output pressure for HIFU applications is discussed. Higher output pressure of a CMUT cell can be achieved by adding one extra fabrication step to the existing fabrication process. Two-dimensional transducer arrays are required for electronic focusing and beam steering. An 8-channel continuous wave (CW) excitation system is developed to drive a 2-D CMUT array. This 8-channel system minimizes the system complexity without significant loss of focusing capability, compared to a full system with hundreds to thousands of channels. The first successful 2-D CMUT array fabricated using the thick-buried-oxide (BOX) process is presented. The breakdown issue of the insulation layer observed in the test stage is investigated as well. Another type of 2-D CMUT array fabricated using the sacrificial-release process is also tested for HIFU applications. Using the 8-channel CW excitation system, the 2-D CMUT array has proven to be able to produce enough output pressure for thermal ablation. This dissertation presents the result of ex-vivo experiments, which created thermal lesions on bovine tissue using a CMUT array for the first time.
Capacitive micromachined ultrasonic transducers with substrate-embedded springs [electronic resource]
Keywords: Electrical Engineering.

After the first capacitive micromachined ultrasonic transducer (CMUT) was invented in 1994, it became one of the candidate technologies to advance the state-of-the-art of medical ultrasound imaging. Benefiting from its fabrication technique based on the semiconductor industry, CMUT technology has broadened the medical and therapeutic applications such as real-time volumetric ultrasound imaging, catheter-based forward-looking intravascular ultrasound (IVUS), photoacoustic imaging, high-intensity focused ultrasound (HIFU) and so on. In spite of many advantages, however, CMUT technology has been criticized with its relatively low transmit sensitivity (~10 kPa/V) or low average volume displacement efficiency (0.1 nm/V) as well as large drive and bias voltage requirements (in a range of a few hundreds of volts). In order to resolve these issues and open up new potential of clinical applications, this dissertation describes the design, fabrication, and system implementation of CMUTs with substrate-embedded springs, so-called post-CMUT (PCMUT). Since PCMUT structure resembles an ideal piston transducer, the improvements in performance mainly stem from the higher average displacement of the top plate for a given gap height. The overview of the first generation PCMUT is introduced and two main issues in simulation and fabrication aspects of the first generation PCMUT is discussed. To further improve the PCMUT device, a 3D finite element analysis (FEA) model of the PCMUT is demonstrated to predict the performance of the first generation PCMUT. In addition, the design guideline of the second generation PCMUT is proposed for achieving the maximum fractional bandwidth (100 %) as well as with the highest transmit sensitivity (~28 kPa/V). The second generation PCMUT is fabricated by using three combination MEMS processes: usage of two silicon-on-insulator (SOI) wafers, wafer bonding process, and wafer polishing process. The second generation PCMUT achieves high transmit sensitivity (~21 kPa/V) or large average volume displacement efficiency (1.1 nm/V) with a low bias voltage (55 V). Compared to a commercial piezoelectric transducer, the second generation PCMUT improves 2.75 times of the maximum output pressure and 5.25 times of the average volume displacement efficiency with respect to the same voltage. After fabrication and performance characterization of the second generation PCMUT, this dissertation demonstrates the feasibility of PCMUT to use it in medical imaging system by integrating PCMUT with a custom-built integrated circuit (IC). Photoacoustic imaging is also presented for one of its application examples.