Extraction of paleohydrology and paleoclimate proxies from vadose zones and paleolake records in the southwestern Great Basin

Thick vadose zones in arid regions recorded past climate changes up to 100 ka, so they are unique archives for continental paleoclimate change and groundwater recharge during the late Quaternary. Despite extensive research on flow and transport in arid regions, the transport properties and general response of arid vadose zones to climate regimes are still not well understood. Some of these issues are addressed with four distinct studies in this dissertation. The first study investigates effects of soil texture, vegetation coverage, and macropores on soil moisture variation at Nevada Test Site (NTS). The simulations show that bare soils have higher soil water content than vegetated soils. Effects of macropore flow on soil water content are insignificant; The second study evaluates the impacts of climate change on solute transport in arid vadose zones. Undisturbed soil cores were collected at ground surface, directly below where tension infiltrometer measurements were made. The water fluxes and Br dispersion coefficients at investigated matric heads were very high due to the coarseness of the soils and possibly due to preferential flow pathways. These high water fluxes are more likely to occur in ephemeral washes. However, higher fluxes through the surface soil would be more likely during wetter climates; The third study simulates paleolake extent in Owens Valley in the last 18 ka. A coupled catchment-lake model is developed in this study, and used to reconstruct the observed paleolake levels for Owens Lake and Searles Lake. Finally, a quantitative time-series of paleoclimate information was obtained; The fourth study models the actual measured chloride profile in Amargosa Desert Research Site (ADRS) with the modified version of the HYDRUS-1D computer code by using variable boundary conditions. The paleoinformation estimated from the third study, and chloride concentration in Greenland ice core (GISP2) are used to prepare the atmospheric boundary file. The simulated chloride profile is in agreement with the measured chloride profile, and simulated water flux at ADRS is ∼0.016 mm/year upward at the base of the profile; Transport properties and general response of vadose zones to climate regimes are addressed by these four independent studies

Trust In and Adoption of Online Recommendation Agents

Online product recommendation agents are becoming increasingly prevalent on a wide range of websites. These agents assist customers in reducing information overload, providing advice to find suitable products, and facilitating online decision-making. Consumer trust in recommendation agents is an integral factor influencing their successful adoption. However, the nature of trust in technological artifacts is still an under-investigated and not well understood topic. Online recommendation agents work on behalf of individual users (principals) by reflecting their specific needs and preferences. Trust issues associated with online recommendation agents are complicated. Users may be concerned about the competence of an agent to satisfy their needs as well as its integrity and benevolence in regard to acting on their behalf rather than on behalf of a web merchant or a manufacture. This study extends the interpersonal trust construct to trust in online recommendation agents and examines the nomological validity of trust in agents by testing an integrated Trust-TAM (Technology Acceptance Model). The results from a laboratory experiment confirm the nomological validity of trust in online recommendation agents. Consumers treat online recommendation agents as social actors and perceive human characteristics (e.g., benevolence and integrity) in computerized agents. Furthermore, the results confirm the validity of Trust-TAM to explain online recommendation acceptance and reveal the relative importance of consumers\u27 initial trust vis-¨¤-vis other antecedents addressed by TAM (i.e. perceived usefulness and perceived ease of use). Both the usefulness of the agents as tools and consumers\u27 trust in the agents as virtual assistants are important in consumers\u27 intentions to adopt online recommendation agents

Effects of Impulse and Habit on Privacy Disclosure in Social Networking Sites: Moderating Role of Privacy Self-Efficacy

Prior research on privacy disclosure primarily focuses on conscious factors leading to intentional disclosure. In this study, we identify two unconscious factors, i.e., the habit of self- disclosure and the impulse of self-disclosure, which lead to users’ privacy disclosure behavior in social networking sites (SNS). We contribute to the existent literature by investigating the effects of these two factors on privacy disclosure behavior in SNS and examining a contingent factor for the effects of these two unconscious factors. Our results reveal that both habit and impulse have significant effects on privacy disclosure in SNS. The effects of habit and impulse are moderated by users’ privacy self-efficacy. Particularly, privacy self-efficacy weakens the effects of impulse on self-disclosure but strengthens the effect of habit on self-disclosure

The Effects of Portal Affiliations and Self-Proclaimed Assurance on Consumer Trust: Investigating Customers\u27 Purpose of Visit as a Moderator

Customers sometimes visit Internet stores just for fun, without strong intentions to purchase a product (hereafter to browse ), and they sometimes visit with strong intentions to purchase a product (hereafter to purchase ). Our research question is whether or not customers respond to the same interface features in a different manner depending on their purpose of visit (e.g., to browse or to purchase). We believe that this is an important question for Internet stores. If Internet stores can predict different influence of a certain web interface feature on customers who have strong purchase intentions from the store, then they can design Web shopping sites to serve those customers more effectively. For example, assuming that those customers who visit to purchase usually conduct checkout processes, while those who visit to browse are less likely to conduct checkout processes, it would be effective to include the Web interface features that are especially effective for those who visit to purchase in the checkout screens. This study will investigate whether or not customers\u27 purpose of visit (e.g., to purchase or to browse) moderates the impact of portal affiliation and a store\u27s self-proclaimed assurance on customer trust. A laboratory experiment is designed to investigate whether or not customers who have a different purpose of visit respond to portal affiliation and self-proclaimed assurance in a different manner

Multi-network Contrastive Learning Based on Global and Local Representations

The popularity of self-supervised learning has made it possible to train models without relying on labeled data, which saves expensive annotation costs. However, most existing self-supervised contrastive learning methods often overlook the combination of global and local feature information. This paper proposes a multi-network contrastive learning framework based on global and local representations. We introduce global and local feature information for self-supervised contrastive learning through multiple networks. The model learns feature information at different scales of an image by contrasting the embedding pairs generated by multiple networks. The framework also expands the number of samples used for contrast and improves the training efficiency of the model. Linear evaluation results on three benchmark datasets show that our method outperforms several existing classical self-supervised learning methods

Evaluation of the Effect of Saturated Silty and Fine Sand Foundation Improved by Vibro-Flotation in Seismic Area

The improvement of liquefaction foundations in seismic region has been concerning many engineers. The authors had carried out experimental studies on the improvement of saturated silty and fine sand foundations at the suburbs of Beijing by vibroflotation method. The test results are described and the improvement effects are evaluated in this paper

How Story Works in Mobile App Stores? Exploring the Same-Side Effect from the Storytelling Perspective

The growing number of mobile apps has contributed to an innovation diffusion paradox whereby the accelerated pace with which mobile apps are being developed and updated has stymied their own diffusion. Due to consumers’ limited personal involvement with mobile apps, storytelling, as an emerging and novel product recommendation format, is gaining traction as a promotional mechanism for diffusing mobile apps within the ecosystem. Storytelling is particularly amenable to the context of mobile app stores by giving affective meaning to the focal app being promoted and strengthening its association with other apps available from these stores. To this end, we construct a research model to illustrate how consumers’ demand for related mobile apps is shaped by similarity in functional and visual attributes between these apps and the focal app being promoted via storytelling. Our model also sheds light on how the preceding effects could be mitigated by within-developer influence