Aerodynamic pressure and heating-rate distributions in tile gaps around chine regions with pressure gradients at a Mach number of 6.6

Surface and gap pressures and heating-rate distributions were obtained for simulated Thermal Protection System (TPS) tile arrays on the curved surface test apparatus of the Langley 8-Foot High Temperature Tunnel at Mach 6.6. The results indicated that the chine gap pressures varied inversely with gap width because larger gap widths allowed greater venting from the gap to the lower model side pressures. Lower gap pressures caused greater flow ingress from the surface and increased gap heating. Generally, gap heating was greater in the longitudinal gaps than in the circumferential gaps. Gap heating decreased with increasing gap depth. Circumferential gap heating at the mid-depth was generally less than about 10 percent of the external surface value. Gap heating was most severe at local T-gap junctions and tile-to-tile forward-facing steps that caused the greatest heating from flow impingement. The use of flow stoppers at discrete locations reduced heating from flow impingement. The use of flow stoppers at discrete locations reduced heating in most gaps but increased heating in others. Limited use of flow stoppers or gap filler in longitudinal gaps could reduce gap heating in open circumferential gaps in regions of high surface pressure gradients

Saturated-Unsaturated flow in a Compressible Leaky-unconfined Aquifer

An analytical solution is developed for three-dimensional flow towards a partially penetrating large-diameter well in an unconfined aquifer bounded below by an aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage assumption due to Neuman [1972]. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The investigation of model-predicted results shows that leakage from an underlying aquitard leads to significant departure from the unconfined solution without leakage. The investigation of dimensionless time-drawdown relationships shows that the aquitard drawdown also depends on unsaturated zone properties and the pumping-well wellbore storage effects

Drones: Proposed Standards of Liability

Drones: Proposed Standards of Liabilit

The neurophysiology of biological motion perception in schizophrenia.

IntroductionThe ability to recognize human biological motion is a fundamental aspect of social cognition that is impaired in people with schizophrenia. However, little is known about the neural substrates of impaired biological motion perception in schizophrenia. In the current study, we assessed event-related potentials (ERPs) to human and nonhuman movement in schizophrenia.MethodsTwenty-four subjects with schizophrenia and 18 healthy controls completed a biological motion task while their electroencephalography (EEG) was simultaneously recorded. Subjects watched clips of point-light animations containing 100%, 85%, or 70% biological motion, and were asked to decide whether the clip resembled human or nonhuman movement. Three ERPs were examined: P1, N1, and the late positive potential (LPP).ResultsBehaviorally, schizophrenia subjects identified significantly fewer stimuli as human movement compared to healthy controls in the 100% and 85% conditions. At the neural level, P1 was reduced in the schizophrenia group but did not differ among conditions in either group. There were no group differences in N1 but both groups had the largest N1 in the 70% condition. There was a condition × group interaction for the LPP: Healthy controls had a larger LPP to 100% versus 85% and 70% biological motion; there was no difference among conditions in schizophrenia subjects.ConclusionsConsistent with previous findings, schizophrenia subjects were impaired in their ability to recognize biological motion. The EEG results showed that biological motion did not influence the earliest stage of visual processing (P1). Although schizophrenia subjects showed the same pattern of N1 results relative to healthy controls, they were impaired at a later stage (LPP), reflecting a dysfunction in the identification of human form in biological versus nonbiological motion stimuli

On the Internet by Means of Popular Music: The Cases of Grimes and Childish Gambino

What is the internet? It began as a military research experiment, but the internet has since become a sweeping cultural phenomenon. One of the most prevalent areas of the internet’s cultural dominance is in popular music, and this thesis addresses how the internet is being understood and discussed by popular music artists. I study the works of Grimes and Childish Gambino, two popular music artists who grew up alongside the internet’s rise to cultural dominance and explicitly address this experience as an integral component of their lives and works. I look specifically at discourse surrounding Grimes’ “post-internet” music and Childish Gambino’s expansive conceptual work Because the Internet (2013). This research concludes by addressing how popular music artists like Grimes and Childish Gambino are helping produce the ways in which we understand and discuss the cultural phenomenon of the internet, and how they provide a foundation for future artists and research to build upon

Jump-Starting the Internet Revolution: How Structural Conduciveness and Global Connections Help Diffuse the Internet

The growing perception that the Internet is becoming an engine of global economic and social change has inspired both governments and intergovernmental agencies to accelerate the diffusion of the Internet around the globe via multimillion dollar programs and initiatives. Unfortunately, few empirical studies guide these initiatives. The purpose of this research is to investigate the causes that drive Internet capacity, with special emphasis on diffusion theory. Global diffusion of IT requires some degree of structural conduciveness (similarities between developed and developing countries in economic, political, and social structures) as well as contact with developed countries. In our pooled time-series models of 58 developing nations over the 1995-2000 time period, we find that both structural conduciveness (i.e., teledensity, service economies, political openness, and global urban share) and globalization (i.e., aid share, tourist share, foreign investment share, and trade share) shape the distribution and growth of Internet usage

Matrix Microarchitecture and Myosin II Determine Adhesion in 3D Matrices

SummaryBackgroundReports of adhesions in cells growing in 3D vary widely—from nonexistent to very large and elongated—and are often in apparent conflict, due largely to our minimal understanding of the underlying mechanisms that determine 3D cell phenotype. We address this problem directly by systematically identifying mechanisms that determine adhesion in 3D matrices and, from our observations, develop principles widely applicable across 2D and 3D substrates.ResultsWe demonstrate that nonmuscle myosin II activity guides adhesion phenotype in 3D as it does in 2D; however, in contrast to 2D, decreasing bulk matrix stiffness does not necessarily inhibit the formation of elongated adhesions. Even in soft 3D matrices, cells can form large adhesions in areas with appropriate local matrix fiber alignment. We further show that fiber orientation, apart from influencing local stiffness, modulates the available adhesive area and thereby determines adhesion size.ConclusionsThus adhesion in 3D is determined by both myosin activity and the immediate microenvironment of each adhesion, as defined by the local matrix architecture. Important parameters include not only the resistance of the fiber to pulling (i.e., stiffness) but also the orientation and diameter of the fiber itself. These principles not only clarify conflicts in the literature and point to adhesion modulating factors other than stiffness, but also have important implications for tissue engineering and studies of tumor cell invasion

INTERACTION-BASED SECURITY FOR MOBILE APPS

Mobile operating systems pervade our modern lives. Security and privacy is of particular concern on these systems, as they have access to a wide range of sensitive resources. Apps access these sensitive resources to help users perform tasks. However, apps may use these sensitive resources in a way that the user does not expect. For example, an app may look up reviews of restaurants nearby, but also leak the user’s location to an ad service every hour. I claim that interaction serves as a valuable component of security decisions, because the user’s interaction with the app’s user interface (UI) deeply informs their mental model of how apps access sensitive data. I introduce the notion of interaction-based security, wherein security decisions are driven by this interaction. To help understand and enforce interaction-based security, I present four pieces of work. The first is Redexer, which performs binary instrumentation of off-the-shelf Android binaries. Binary instrumentation is a useful tool for enforcing and studying security properties. I demonstrate one example of how Redexer can be used to study location privacy in apps. Android permissions constrain how data enters apps, but do not constrain how the information is used or where it goes. Information-flow allows us to formally define what it means for data to leak from applications, but it is unclear how to use information-flow policies for Android apps, because apps frequently declassify information. I define interaction-based declassification policies, and show how they can be used to define policies for several example apps. I then implement a symbolic executor which checks Android apps to ensure they respect these policies. Next, I test the hypothesis that the app’s UI influences security decisions. I outline an app study that measures when apps use sensitive resources with respect to their UI. I then conduct a user study to measure how an app’s UI influences their expectation that a sensitive resource will be accessed. I find that interactivity plays a large role in determining user expectation of sensitive resource use, and that apps largely access sensitive resources interactively. I also find that users may not always understand background uses of these sensitive resources and using them expectation requires special care in some circumstances. Last, I present a tool which can help a security auditor quickly understand how apps use resources. My tool uses a novel combination of app logging, symbolic execution, and abstract interpretation to infer a formula that holds on each per- mission use. I evaluate my tool on several moderately-sized apps and show that it infers the same formulas we laboriously found by hand

Rare Diatom Stauroneis schinzii (Brun) Cleve var. schinzii Microfossil Collected and Georeferenced in Alabama

The diatom Stauroneis schinzii (Brun) Cleve var. schinzii has an underreported record of its autecology, distribution, and natural history. While the species is found in Africa and South America, it is rare in North America and very few specimens have been collected and cataloged. As part of a landscape evolution study, we cored the sediments of an oxbow lake in the coastal plain of Alabama, USA, for diatom analysis. Among 40,608 individual diatoms sampled, we counted a single valve of S. s. var. schinzii, georeferenced its location, and recorded a micrograph. Based on the carbon dating of the sediment core, we conclude the diatom was not anthropogenically introduced from another continent