Hydrocarbon Seepage at Campeche-Sigsbee Salt Province, Southern Gulf of Mexico (Detection, Mapping, and Seafloor Manifestation)

Hydrocarbon seepage is a process during which hydrocarbon fluids are emitted from the seafloor into the water column. This phenomenon has been observed globally from continental margins to the deep abyssal. Hydrocarbon seepage has significant impacts on the marine environment such as (a) influence on sediment composition and dynamics at the seafloor, (b) increasing the habitat heterogeneity on seep biodiversity and (c) contributes to the global carbon cycle. However, the occurrence, distribution, and dynamics of hydrocarbon seepage in the marine environment, especially in the deep ocean remains unclear due to limited investigation. The northern Gulf of Mexico is a well-known prolific petroleum-producing region where numerous gas and oil emissions, associated with salt tectonism, have been observed. The Campeche-Sigsbee salt province in the southern GoM is considered to be an analog to the salt province in the northern GoM, but there has been very little research conducted in this region. Based on the occurrence of natural oil slicks on the sea surface resolved by satellite images, previous studies suggested that there is a widespread distribution of oil seeps in the Campeche-Sigsbee salt province. However, there is still a lack of direct evidence for the presence and the distribution of gas emissions. In addition to gas and oil seepage, Chapopote asphalt volcanism, a novel type of hydrocarbon seepage was first introduced in 2003. Since then, submarine asphalt deposits have attracted considerable research interest. This study aims to have a comprehensive understanding of the hydrocarbon seepage system and dynamics in the southern GoM. The objectives are to investigate the distribution of gas emissions and to understand the controlling factors on the distribution. Furthermore, detailed investigations were carried out at Challenger Knoll and Mictlan Knoll to gain a better understanding of the diverse hydrocarbon seepage system including gas and oil emissions, as well as asphalt deposits. Consequently, the research questions about the fate of the methane bubbles and the quantity of gas bubble released from gas emission site are finally addressed in this study. During research cruise M114 of R/V METEOR, a multidisciplinary approach was conducted, including hydroacoustic surveys, visual seafloor observations, and sampling of gas bubbles. Ship-based multibeam echosounder was used for seafloor bathymetry, backscatter and water column flare mapping in the Campeche-Sigsbee salt province. In addition, multibeam echosounder mounted on Autonomous Underwater Vehicle (AUV) was utilized to obtain high-resolution seafloor bathymetry, backscatter, and water column data at Mictlan Knoll. Remotely Operated Vehicle (ROV) and TV-sled were applied for investigating and documenting seafloor manifestations of hydrocarbon seepage at the seafloor. Gas bubbles were collected by pressure-tight gas bubble samplers operated by ROV at the seafloor of Mictlan Knoll for gas analyses, quantification of gas bubble emissions, and finally gas flux calculation. In summary, gas emissions are found in large numbers in the Campeche-Sigsbee salt province. Their distributions are controlled by the present geological structures. The case study in the Sigsbee Knolls suggests that the edges of flat-top knolls might provide an effective migration pathway for hydrocarbons. As there is no direct evidence for the presence of current oil seepage in the Sigsbee Knolls, we suggested that oil seepage occurs intermittently. Gas, oil seepage and asphalt volcanism are found to occur close together at the Mictlan Knoll, indicating that this diverse hydrocarbon seepage system might be a common phenomenon in the Campeche Knolls. This thesis shows the complex association between the dynamics of diverse hydrocarbon seepage and the geological controls in the southern GoM

The Optimal Ordering Periods for Internet Shopping under Time Dependent Consumer Demand

This study attempts to determine the optimal goods ordering periods for internet stores by considering time-dependent consumer demands and close demand-supply interactions. In order to capture dynamic and time-sensitive consumers, the entire study period is divided into a number of ordering periods with various duration. In the demand side, the study formulates a consumer utility function to construct a binary logit model, which determines consumers’ choice probabilities between internet shopping and conventional in-store shopping. The expected choice probability of choosing internet shopping is aggregated by a transformation probability density function of individual income based on the logit model. Then, the study further aggregates individual consumer choice probability to estimate the total demand for internet stores by considering variations in access time to retail stores, and delay time of receiving ordered goods. In the supply side, the study formulates transportation costs considering extra labor cost due to 24 hours business hours of internet stores, and constructs inventory costs reflecting the relationship between the batch ordering of goods, which are made by internet store operators to their suppliers and continuous ordering of goods, which are made by their consumers. Finally, a case study and sensitivity analysis are provided by R-company in Taiwan to illustrate the application of the models. The results show how the operators of internet stores should determine the number and duration of ordering periods in response to time-dependent consumer demand, thereby maximizing their profits

Interactions Between Reinforcement Corrosion and Chloride Ion Diffusion in Mortar

This study explored the diffusion of the chloride ions influenced by the reinforcement corrosion in the mortar. It is believed that, during the corroding process, a small current is generated at the surface of the reinforcement. Such current is supposed to influence the diffusion of the chloride ions, but the relationship between both was not well studied in the literature. In this study, the corroded reinforcements were prepared by applied currents. Reinforced mortar specimens with w/c of 0.6 were then prepared and cured by either salt or fresh water. Results showed that the chloride ion distribution was likely associated with the reinforcement corrosion. During the early hydration, the chloride ions were attracted by the reinforcement corrosion in the specimens prepared with fresh water and cured in salt water. The concentration of the chloride ions near the surface of the reinforcement was increased with the increases of the charging time during the preparation for the corroded reinforcement. On the contrary, the chloride ions were likely bound in those specimens prepared with salt water and cured by saturated lime water. The concentration of the chloride ions near the surface of the reinforcement was higher than those near the outer surface. However, such influencing effects were not clear in the long term, possibly due to the hydration. The results of this study show that the reinforcement corrosion have influences on the diffusion of the chloride ions and such effect should be considered during the refinement of the traditional chloride ion diffusion models

Space Net Optimization

Most metaheuristic algorithms rely on a few searched solutions to guide later searches during the convergence process for a simple reason: the limited computing resource of a computer makes it impossible to retain all the searched solutions. This also reveals that each search of most metaheuristic algorithms is just like a ballpark guess. To help address this issue, we present a novel metaheuristic algorithm called space net optimization (SNO). It is equipped with a new mechanism called space net; thus, making it possible for a metaheuristic algorithm to use most information provided by all searched solutions to depict the landscape of the solution space. With the space net, a metaheuristic algorithm is kind of like having a ``vision'' on the solution space. Simulation results show that SNO outperforms all the other metaheuristic algorithms compared in this study for a set of well-known single objective bound constrained problems in most cases.Comment: 12 pages, 6 figure

Exploring the Impact of Different Sources Credibility on App Downloading Behavior: An ELM Perspective

With the increasing of using smart phone, people began to use “App” in their daily life. While they need to download a specific type of App, the developer of the App will provide them an introductory page which describes the functionality of the App and contains statistical data. Besides, function of “your friend who has downloaded this App” is introduced to smart phone users. Therefore, many peripheral cues are listed in the page nowadays to persuade people to download. The purpose of this study is to understand whether peripheral cues in the introductory page can persuade people to download this App. In our study, we used ELM-based theory to explain the behavior of persuading. The expected contribution of this study is to understand three peripheral cues would influence App credibility which influence attitude toward downloading. This study will provide advices to App developers to promote their strategies of business

Is Explanation the Cure? Misinformation Mitigation in the Short Term and Long Term

With advancements in natural language processing (NLP) models, automatic explanation generation has been proposed to mitigate misinformation on social media platforms in addition to adding warning labels to identified fake news. While many researchers have focused on generating good explanations, how these explanations can really help humans combat fake news is under-explored. In this study, we compare the effectiveness of a warning label and the state-of-the-art counterfactual explanations generated by GPT-4 in debunking misinformation. In a two-wave, online human-subject study, participants (N = 215) were randomly assigned to a control group in which false contents are shown without any intervention, a warning tag group in which the false claims were labeled, or an explanation group in which the false contents were accompanied by GPT-4 generated explanations. Our results show that both interventions significantly decrease participants' self-reported belief in fake claims in an equivalent manner for the short-term and long-term. We discuss the implications of our findings and directions for future NLP-based misinformation debunking strategies.Comment: EMNLP Findings 202

Permutationless Many-Jet Event Reconstruction with Symmetry Preserving Attention Networks

Top quarks, produced in large numbers at the Large Hadron Collider, have a complex detector signature and require special reconstruction techniques. The most common decay mode, the "all-jet" channel, results in a 6-jet final state which is particularly difficult to reconstruct in $pp$ collisions due to the large number of permutations possible. We present a novel approach to this class of problem, based on neural networks using a generalized attention mechanism, that we call Symmetry Preserving Attention Networks (SPA-Net). We train one such network to identify the decay products of each top quark unambiguously and without combinatorial explosion as an example of the power of this technique.This approach significantly outperforms existing state-of-the-art methods, correctly assigning all jets in $93.0$ of $6$-jet, $87.8$ of $7$-jet, and $82.6$ of $\geq 8$-jet events respectively.Comment: 8pages, submitted to PRL, revised version with updated result

Fluoroquinolones are associated with delayed treatment and resistance in tuberculosis: a systematic review and meta-analysis

SummaryBackgroundCurrent guidelines for treating community-acquired pneumonia recommend the use of fluoroquinolones for high-risk patients. Previous studies have reported controversial results as to whether fluoroquinolones are associated with delayed diagnosis and treatment of pulmonary tuberculosis (TB) and the development of fluoroquinolone-resistant Mycobacterium tuberculosis. We performed a systematic review and meta-analysis to clarify these issues.MethodsThe following databases were searched through September 30, 2010: PubMed, EMBASE, CINAHL, Cochrane Library, Web of Science, BIOSIS Previews, and the ACP Journal Club. We considered studies that addressed the issues of delay in diagnosis and treatment of TB and the development of resistance.ResultsNine eligible studies (four for delays and five for resistance issues) were included in the meta-analysis from the 770 articles originally identified in the database search. The mean duration of delayed diagnosis and treatment of pulmonary TB in the fluoroquinolone prescription group was 19.03 days, significantly longer than that in the non-fluoroquinolone group (95% confidence interval (CI) 10.87 to 27.18, p<0.001). The pooled odds ratio of developing a fluoroquinolone-resistant M. tuberculosis strain was 2.70 (95% CI 1.30 to 5.60, p=0.008). No significant heterogeneity was found among studies in the meta-analysis.ConclusionsEmpirical fluoroquinolone prescriptions for pneumonia are associated with longer delays in diagnosis and treatment of pulmonary TB and a higher risk of developing fluoroquinolone-resistant M. tuberculosis

UNDERSTANDING COMPETITIVE PERFORMANCE OF SOFTWARE-AS-A-SERVICE (SAAS)—THE COMPETITIVE DYNAMICS PERSPECTIVE

Understanding the antecedents and consequences of a firm’s agility in cloud software applications is important. This papers draws on the competitive dynamics perspective to develop a model that explains the relationships between collaboration with vendors, agility, and competitive performance in software-as-a-service (SaaS) context. Collaboration reflects a firm’s ability to leverage interfirm resources, characterized as knowledge sharing and process alignment. Agility is measured by a firm’s strategy-oriented agility and service-oriented agility. This study also investigates the moderating effect of environmental turbulence. The proposed hypotheses are supported by the empirical data. The results show that competitive performance is affected by ability, which, in turn, is impacted by collaboration. Environmental turbulence positively moderates the relationship between agility and performance. Finally, we discuss the implications of our results