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Since the Internet first became a mainstream form of communication, researchers have sought to understand its impact on civic engagement. Given the unprecedented ability of Internet users to access volumes of information and news sources, connect with like-minded people around the world, and communicate instantaneously, it is important to understand how the Internet changes our community relationships and civic engagement. While early research painted a largely positive picture of the Internet’s impact, more recent work has pointed to the dangers posed by online echo chambers, misinformation, and the substitution of virtual interactions for real-life community activities. Against this backdrop, we explore the relationship between Internet use and voting in the 2016 and 2018 U.S. elections, paying particular attention to different kinds of devices, technologies, and online activities. In testing a statistical model of voting that includes indicators of Internet use and other relevant characteristics, we merge overlapping samples from four supplements to the U.S. Census Bureau’s Current Population Survey. First, the November 2017 edition of the National Telecommunications and Information Administration’s (NTIA) Internet Use Survey captures extensive information about Internet adoption and various devices used by Americans. The November 2016 and November 2018 Voting and Registration Supplements capture information regarding voter registration, turnout, and reported reasons for not voting. Finally, the September 2017 Volunteering and Civic Life Supplement captures other important markers of civic engagement, such as the various ways in which people volunteer and participate in activities in their communities. Taking advantage of the Current Population Survey’s sample design, which leads to households being included in eight monthly data collections over the course of sixteen months, we examine voting and Internet use while also controlling for variables such as ethnicity, age, gender, education, and income. Our preliminary findings suggest that Internet use was positively related to voter turnout in both the 2016 presidential election and 2018 midterm election. In both 2016 and 2018, an Internet user was more likely to vote than a non-user after controlling for other factors believed to be related to voter turnout. Other results are equally illuminating; for example, PC or tablet computer use was associated with a higher likelihood of voting, while smartphone use had no statistically significant impact. It is these and other results that our group incorporates into the paper and weaves a story about how the Internet impacts American civic participation.

Financial technology (fintech), including mobile money services, peer-to-peer lending, and mobile insurance is promised as a means to economic inclusion for the un(der)banked. These online financial services, however, require Internet access, adoption, and digital literacy. Given the important interdependencies between banking and Internet adoption in the United States, this paper merges datasets from FDIC’s June 2015 Unbanked and Underbanked survey and NTIA’s July 2015 Computer and Internet Use survey to study the issue more closely. While the process of merging CPS supplements at the household level is fairly straightforward, treating sampling weights and variance raises some complications. Our paper proposes a methodology for merging CPS supplements and addressing these issues. The merged dataset shows a strong relationship between the un(der)banked and the level of Internet activity, as measured both through the type of Internet service(s) used and the types of devices used by the household. For example, nearly half (47 percent) of unbanked households do not have a fixed or mobile Internet connection. Likewise, while less than 40 percent of the unbanked households rely on multiple types of devices, roughly 75 percent of the underbanked and banked households use multiple types of devices. Results suggest that, to successfully expand financial inclusion in the US, fintech could require Internet access, adoption, and digital literacy training.

Atoll and island coastal communities are highly exposed to sea-level rise, tsunamis, storm surges, rogue waves, king tides, and the occasional combination of multiple factors, such as high regional sea levels, extreme high local tides, and unusually strong wave set-up. The elevation of most of these atolls averages just under 3 meters (m), with many areas roughly at sea level. The lack of high-resolution topographic data has been identified as a critical data gap for hazard vulnerability and adaptation efforts and for high-resolution inundation modeling for atoll nations. Modern topographic survey equipment and airborne lidar surveys can be very difficult and costly to deploy. Therefore, unmanned aircraft systems (UAS) were investigated for collecting overlapping imagery to generate topographic digital elevation models (DEMs). Medium- and high-resolution satellite imagery (Landsat 8 and WorldView-3) was investigated to derive nearshore bathymetry. The Republic of the Marshall Islands is associated with the United States through a Compact of Free Association, and Majuro Atoll is home to the capital city of Majuro and the largest population of the Republic of the Marshall Islands. The only elevation datasets currently available for the entire Majuro Atoll are the Shuttle Radar Topography Mission and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model Version 2 elevation data, which have a 30-m grid-cell spacing and a 8-m vertical root mean square error (RMSE). Both these datasets have inadequate spatial resolution and vertical accuracy for inundation modeling. The final topobathymetric DEM (TBDEM) developed for Majuro Atoll is derived from various data sources including charts, soundings, acoustic sonar, and UAS and satellite imagery spanning over 70 years of data collection (1944 to 2016) on different sections of the atoll. The RMSE of the TBDEM over the land area is 0.197 m using over 70,000 Global Navigation Satellite System real-time kinematic survey points for validation, and 1.066 m for Landsat 8 and 1.112 m for WorldView-3 derived bathymetry using over 16,000 and 9,000 lidar bathymetry points, respectively.

An underwater acoustic modem capable of point-to-point transmission of data at high bit rates is presented in this article. The high data-rate acoustic uplink operates between 262 kHz and 375 kHz in three sub-bands. The lower sub-band (262.5 kHz to 337.5 kHz) carries the binary information. The middle sub-band (347-373 kHz) is for detection purposes. The higher sub-band carries a narrow-band, 375-kHz tone designed to improve the Doppler-tracking capability of the high bit-rate acoustic uplink. The acoustic uplink uses phase-modulated symbols of adjustable bandwidth (25 kHz, 50 kHz or 75 kHz). The peak data rate is 87,768 bits-per-second at a maximum range of 180 m using an omni-directional source and an omni-directional receiver. The source level required to achieve this range is 185.8 dB re 1 μPa at 1 m. This modem is also equipped with an acoustic downlink designed for command-and-control in a lower frequency band (62-76 kHz) and at a lower data rate. The focus of this paper is on the high bit-rate uplink. A series of experimental results demonstrate that this underwater acoustic modem can operate reliably in difficult environments such as ports and very shallow waters. High-resolution sonar images are transmitted in real-time from various types of autonomous underwater vehicles during the inspection of ship hulls, walls and sea bottom.

Access to ubiquitous and affordable high-speed Internet is essential to many aspects of modern society. The Internet can assist in activities like accessing employment opportunities, healthcare options, affordable housing, and educational resources. However, millions of Americans still do not use the Internet, and even among those who do, the speed, quality and form of access can vary greatly. We seek to better understand the challenges faced by non-adopters and under-connected Americans using new data from the July 2015 Computer and Internet Use Supplement to the Current Population Survey. We find that the nature of the digital divide is evolving. As usage habits and technologies change, new disparities are appearing, even while others gradually narrow. New divides based on the cost of owning multiple Internet-enabled devices appear to be surfacing. To better understand the changing needs of underserved communities, we examine three important and emerging trends. First, we analyze survey data from Internet non-adopters. NTIA added new questions to its 2015 survey in order to better understand why households report not using the Internet. We allowed households to report multiple reasons for not using the Internet, enabling us to better understand why some households are not online. We also asked whether households lacking home Internet service would subscribe to such a service if it were offered at a lower price. Second, we look specifically at one group of low adopters: rural communities. Americans in rural communities may face a disadvantage based on cumulative impact of various barriers to Internet use. For example, rural areas often face high broadband deployment costs, and may lack local facilities that offer public Internet access (e.g., community centers). Together, these factors may further depress Internet use in rural areas among those demographic groups already facing disparities, such low-income households. To understand these issues, we compare Internet use for similar demographic groups in rural and urban areas. Research suggests that, particularly among groups traditionally affected by the digital divide, Internet adoption rates are lower in rural areas.Third, we focus on the diversification of devices used to access the Internet. The proliferation of devices means more people have more alternatives for getting online. However, this trend may open up a new digital divide, based on whether an individual has access to the right type of device for a particular task. Using a smartphone to access the Internet, for example, has qualitative strengths and weaknesses compared to using a laptop computer. To better understand this new divide, we investigate device use, particularly for those most likely to be on the wrong side of the digital divide.Stimulating greater Internet use is an important and widely-prioritized public policy goal. In considering the best strategies to reach this goal, it is important to have a full, nuanced, and granular picture of the digital divide. Looking ahead, policy makers need to better understand how this divide is evolving with Internet and technology usage. Our paper aims to address these questions.

Diabetic cardiomyopathy is a clinically distinct disease characterized by impaired cardiac function as a result of reduced contractility and hypertension-induced athero- or arteriosclerosis. This may be due either to generalized vascular disease, tissue-based injury such as focal cardiomyocyte dysmorphia, or microvascular damage manifested by myocardial capillary basement membrane (CBM) thickening. Hyperglycemia-driven increases in reactive oxygen species (ROS) have been proposed to contribute to such damage. To address this hypothesis, we utilized light (LM) and transmission electron microscopy (TEM) to demonstrate cardiomyocyte morphology and myocardial CBM thickness in the left ventricles of four mouse genotypes: FVB (background Friend virus B controls), OVE (transgenic diabetics), Mt [transgenics with targeted overexpression of the antioxidant protein metallothionein (MT) in cardiomyocytes], and OVEMt (bi-transgenic cross of OVE and Mt) animals. Mice were prepared for morphometric analysis by vascular perfusion. Focal myocardial disorganization was identified in OVE mice but not in the remaining genotypes. Not unexpectedly, myocardial CBM thickness was increased significantly in OVE relative to FVB (P0.05) and Mt (P0.05) animals (+28% and +39.5%, respectively). Remarkably, however, OVEMt myocardial CBMs showed no increase in width; rather they were ~3% thinner than FVB controls. Although the molecular mechanisms regulating CBM width remain elusive, it seems possible that despite a significant hyperglycemic environment, MT antioxidant activity may mitigate local oxidative stress and reduce downstream excess microvascular extracellular matrix (ECM) formation. In addition, the reduction of intra- and perivascular ROS may protect against incipient endothelial damage and the CBM thickening that results from such injury.

Acoustic networks of autonomous underwater vehicles (AUVs) cannot typically rely on protocols intended for terrestrial radio networks. This work describes a new location-aware source routing (LASR) protocol shown to provide superior network performance over two commonly used network protocols—flooding and dynamic source routing (DSR)—in simulation studies of underwater acoustic networks of AUVs. LASR shares some features with DSR but also includes an improved link/route metric and a node tracking system. LASR also replaces DSR's shortest-path routing with the expected transmission count (ETX) metric. This allows LASR to make more informed routing decisions, which greatly increases performance compared to DSR. Provision for a node tracking system is another novel addition: using the time-division multiple access (TDMA) feature of the simulated acoustic modem, LASR includes a tracking system that predicts node locations, so that LASR can proactively respond to topology changes. LASR delivers 2-3 times as many messages as flooding in 72% of the simulated missions and delivers 2–4 times as many messages as DSR in 100% of the missions. In 67% of the simulated missions, LASR delivers messages requiring multiple hops to cross the network with 2–5 times greater reliability than flooding or DSR.

Multiple cooperative vehicles, joined in an acoustic communication network, can perform time-critical, cooperative operations given a robust task allocation mechanism and an efficient path planning model. In this paper, we present solutions for the task-allocation and path-planning problems of the cooperative schema for multiple AUVs: a Location-Aided task Allocation Framework (LAAF) algorithm for multi-target task assignment and the Grid-based Multi-Objective Optimal Programming (GMOOP) mathematical model for finding an optimal vehicle command decision given a set of objectives and constraints. Our research is based on an existing mobile ad-hoc network underwater acoustic simulator and two routing protocols (blind flooding and dynamic source routing). The LAAF and GMOOP controllers combine within a “task-planact” structure to generate an optimized local system output in a timely manner to achieve fleet-wide cooperation. Our preliminary results demonstrate that the location-aided auction strategies perform significantly better than a generic auction algorithm in terms of task-allocation time and network bandwidth consumption. We also demonstrate that the GMOOP path planning technique provides an efficient method for multi-objective tasks by cooperative agents with limited communication capabilities with its results can be referenced in [7]. Prior to this work, existing multi-objective action selection methods were limited to robust networks where constant, reliable communication was available. Both the LAAF and GMOOP algorithms were robust to poor acoustic network conditions and ongoing changing environments. LAAF dynamic task allocation and the GMOOP path planning controller provide an effective solution for cooperative search-classify missions with multiple AUVs under marginal communication conditions.

Hermes is a two-way half-duplex underwater acoustic modem developed to transfer large amounts of information from an underwater asset to a surface operator, while being able to send command-and-control information to the underwater asset. In addition, this communication system must operate in very challenging environments such as busy ports and very shallow waters. Hermes must also provide the ability to transfer data from multiple sources simultaneously, without any impact on the source of information. To do so, the communication system uses a specific pipe architecture tailored for wireless underwater applications, combined with a multi-scale, parallel decision-feedback-equalizer technique. The authors show that Hermes can relay simultaneously and reliably high-resolution scan sonar images with target recognition, mosaics and vehicle status in various port environments, at a range of up to 130 m using high-frequency, omni-directional transducers. The fastest data rate tested is 87,768 bps. The main platform is the Bluefin Robotics HULS3. Experimental results are also presented using the WHOI Remus-100 Gudgeon.

This paper proposes to investigate the performance of a path planning controller for a search-classify mission using multiple cooperative underwater vehicles. We present a control strategy for multi-agent cooperative systems, namely the Grid-based Multi-Objective Optimal Problem (GMOOP) solving technique, to find the optimal solutions for a search-classify mission using an action determination map subject to certain constraints and objectives. This technique is based on an Interval Programming (IvP) algorithm introduced in for representing and optimizing over multiple competing objective functions. We made improvements in this GMOOP technique to suit the harsh underwater acoustic communication environment by taking advantages of the Location-Aware Source Routing (LASR) protocol for underwater Mobile Ad hoc Network (MANET). Preliminary simulation trials based on two simplified scenarios have been carried out. Results show that the demanded cooperative search task could be finished satisfactorily under harsh acoustic constraints, and the performance of the GMOOP model are studied in various aspects.

A new generation of high-speed, high-frequency acoustic modem, named HERMES, has been developed. The acoustic communications link consists of a topside component and an underwater (wet-side) component. Together these components implement two underwater acoustic communication channels: a very high bit rate broadband data uplink and a low bit rate command downlink. The experimental results, obtained with the high-speed high-frequency acoustic uplink, demonstrate the system's ability to transmit high-resolution, uncompressed acoustic images with sufficient quality for any practical purposes. At the fastest data rate (mode 5), HERMES can transmit an uncompressed, high-resolution 400000-bit sonar image in 4.6 seconds. The results presented in this paper demonstrate that these data can be transmitted at a range of 120 m.

A significant problem in missions employing multiple autonomous underwater vehicles (AUVs) is the difficulty of communicating effectively. This challenging communication problem is best addressed in the realm of mobile, ad hoc networking (MANET). This paper describes work towards improving location-aware source routing (LASR), our modification of the dynamic source routing (DSR) protocol to add location awareness and link quality metrics. Specifically designed for use in underwater acoustic networks, LASR is explained and results of investigations into the sensitivity of LASR to medium-model error, tracking error and compression of communicated routing data are shown.

Autonomous underwater vehicles (AUVs) are being used in ever larger numbers, and the rise in the simultaneous use of multiple AUVs is introducing challenging communication problems best addressed in the realm of mobile, ad hoc networking (MANET). This paper describes location-aware source routing (LASR), our modification of the dynamic source routing (DSR) protocol to add location awareness and link quality metrics. A new protocol is needed because of the unique difficulties of underwater networking: radio links do not work through water, and the acoustic links that are used instead have much lower data-rates and much higher latency. Specifically designed for use in underwater acoustic networks, LASR is explained, and initial simulation results are presented to show that the new protocol performs better than two existing techniques.

Potato cell suspension cultures (Solanum tuberosumL. cv. Merrimack) have been selected which are resistant to growth inhibition by D,L-5-methyltryptophan. Anthranilate synthetase activity in crude extracts from resistant cells was less sensitive to feedback inhibition by L-tryptophan and D,L-5-methyltryptophan than the activity from the sensitive line. This altered feedback control apparently accounts for the cell's resistance to growth inhibition since there is a 48-fold increase in free tryptophan in one of the resistant cell lines. Preparative polyacrylamide gel electro-phoresis separated feedback-sensitive and -resistant forms of anthranilate synthetase in extracts from both 5-methyltryptophan-susceptible and -resistant cells, with a predominance of the corresponding form in the respective cell type. The anthranilate synthetase activity from the 5-methyltryptophan-resistant line was inactivated more slowly by incubation of crude extracts at 50°C than the activity from the sensitive line. These results suggest the presence of two isoenzymes of anthranilate synthetase in cultured potato cells.