Essays on the Rationality of Online Romance Scammers

The rapid development of the internet has served an essential role in providing communication platforms for people to choose to have personal interactions. One manifestation is using social media platforms and dating services to establish social relationships. The use of online platforms has also provided unscrupulous individuals with malicious intent the ability to target vulnerable victims using bogus romantic intent to obtain money from them. This type of newly evolved cybercrime is called an online romance scamming. To date, online romance scams have spread to every part of the world (i.e., mainly in the United States, China, Canada, Australia, and the UK) and caused considerable financial and emotional damage to victims. Prior research on online romance fraudsters provides a preliminary understanding of the operational features (stages and persuasive techniques) and their modus operandi. However, the objectivity and relevance of the victimization data in explaining offenders\u27 behaviors may render those studies may represent significant drawbacks. To overcome the limitations, it is important to use actual offender data to generate meaningful analyses of romance fraudsters\u27 behaviors. Consequently, this dissertation aims to use experimental data similar to that applied in my previous work (Wang et al., 2021), combined with existing criminological and communication theories, to promote a better understanding of romance fraudsters\u27 behaviors in the online world. This dissertation begins with a scoping review of the current online romance scam literature, intending to use a scientific strategy to address the existing scholarly gap in this field of research. Derived from rational choice theory, the criminal events perspective, interpersonal deception theory, and neutralization theory, the second and third paper uses an experimental approach to assess the influence of rewards on romance fraudsters\u27 behaviors. The three papers\u27 results demonstrate the rationality of online romance fraudsters when facing rewards. Moreover, such rationality can be explicitly seen from their uses of different linguistic cues. Finally, the outcomes provided in the current project also provide policymakers the information about the rationality and modus operandi of fraudsters which can be used to identify the behavioral patterns at an early phase to prevent significant harm to the victim

Experimental and Numerical Investigations of Wettability of Positive Electrodes for Li−O2 Batteries

The objective of this dissertation is to characterize the positive electrode wettability and its effects on the performance (e.g., discharge capacity) of Li−O2 batteries. The investigations include an experimental study of discharging electrodes with various wettabilities, proposing and examining the intermittent discharge strategy, and the numerical simulation of the distribution of the electrolyte at various saturations and of the discharge performance of Li−O2 batteries at the pore scale. Future work will measure the structure of positive electrodes using advanced imaging technology such as transmission X-ray microscopy. First, I fabricated the electrodes and adjusted their wettability by mixing acetylene black carbon particles with various binders. The wettability was quantitatively characterized by the contact angle and ionic resistance. The customized electrodes were then discharged in Li−O2 batteries at 0.1 mA/cm2 through which the relationship between electrode wettability and discharge capacity was obtained. The discharge capacity of the electrode with 15% PVDF (36.5°) binder was 1665.8 mAh/g while the customized electrode with 15% PTFE (128.4°) binder had a discharge capacity of 4160.8 mAh/g. The effects of lyophobicity on O2 transfer in the porous electrode have been proved. A positive electrode with mixed wettability was designed and tested, which acquired the highest specific discharge capacity of 5149.5 mAh/g. The structure of this electrode included two lyophobic carbon coatings on top and bottom and one lyophilic carbon coating in the middle. Further design may focus on appropriately configuring the wettability to balance the gas paths for O2 diffusion and wetted area for reaction sites. A novel strategy for discharging Li−O2 batteries was then proposed and identified. The battery was periodically discharged and rested, which can enhance O2 availability and increase the discharge capacity. Periodically resting the battery increased the specific discharge capacity by at least 50% at various current densities (0.1 - 1.5 mA/cm2). Afterward, the investigation combined the electrode wettability and the intermittent strategy. Compared with the continuous strategy, the capacity of lyophobic electrodes increased by over 100% when the intermittent strategy was applied. Besides, a multi-step discharge strategy can provide greater capacity when the battery is discharged at decreasing current rates (2.0, 1.5, and 1.0 mA/cm2). The importance of O2 diffusion is emphasized and provide practical strategies are proposed to improve the deep discharge capacity of Li-O2 batteries, especially at high current rates (> 1.0 mA/cm2). Finally, a numerical study was conducted to investigate the electrode with different saturations of the electrolyte. The effects of electrolyte saturation levels and the distribution of electrolyte have been demonstrated by comparing the corresponding discharge performance of Li-O2 batteries. It was found that fully saturated electrodes (100% saturation) have high oxygen transfer resistance, which will result in the lowest discharge capacity of 7.41 Ah/g. On the contrary, over-dried battery (with 1.0 mA/cm2). Finally, a numerical study was conducted to investigate the electrode with different saturations of the electrolyte. The effects of electrolyte saturation levels and the distribution of electrolyte have been demonstrated by comparing the corresponding discharge performance of Li-O2 batteries. It was found that fully saturated electrodes (100% saturation) have high oxygen transfer resistance, which will result in the lowest discharge capacity of 7.41 Ah/g. On the contrary, over-dried battery (with 7 Ah/g) at high current (20 A/m2) similar to hydrophilic electrodes which are fully saturated by the electrolyte at low current (1 A/m2). The modeling study found that designing the electrode with a mixture of lyophilic and lyophobic pores is critical to significantly increasing (by orders of magnitude) the operating current and power of the Li–O2 battery. In the future, plans are to characterize the geometry of the positive electrode using the imaging techniques (e.g., transmission X-ray microscopy) and gas sorption method. Based on the characterization of the porous structure, the relationship between the porous structure and the mass transport phenomena will be clarified

Optimal Redshift Weighting For Redshift Space Distortions

The low statistical errors on cosmological parameters promised by future galaxy surveys will only be realised with the development of new, fast, analysis methods that reduce potential systematic problems to low levels. We present an efficient method for measuring the evolution of the growth of structure using Redshift Space Distortions (RSD), that removes the need to make measurements in redshift shells. We provide sets of galaxy-weights that cover a wide range in redshift, but are optimised to provide differential information about cosmological evolution. These are derived to optimally measure the coefficients of a parameterisation of the redshift-dependent matter density, which provides a framework to measure deviations from the concordance $\Lambda$CDM cosmology, allowing for deviations in both geometric and/or growth. We test the robustness of the weights by comparing with alternative schemes and investigate the impact of galaxy bias. We extend the results to measure the combined anisotropic Baryon Acoustic Oscillation (BAO) and RSD signals.Comment: 10 pages, 5 figures, submitted to MNRA

Quantum Discord for Investigating Quantum Correlations without Entanglement in Solids

Quantum systems unfold diversified correlations which have no classical counterparts. These quantum correlations have various different facets. Quantum entanglement, as the most well known measure of quantum correlations, plays essential roles in quantum information processing. However, it has recently been pointed out that quantum entanglement cannot describe all the nonclassicality in the correlations. Thus the study of quantum correlations in separable states attracts widely attentions. Herein, we experimentally investigate the quantum correlations of separable thermal states in terms of quantum discord. The sudden change of quantum discord is observed, which captures ambiguously the critical point associated with the behavior of Hamiltonian. Our results display the potential applications of quantum correlations in studying the fundamental properties of quantum system, such as quantum criticality of non-zero temperature.Comment: 4 pages, 4 figure

Extraction, isolation, structural characterization, and antioxidant activity of polysaccharides from elderberry fruit

The isolation, purification, and antioxidant activity of polysaccharides extracted from elderberry fruits were studied. Two neutral polysaccharides (EFP-0 and EFP-1) and three acidic polysaccharides (EFP-2, EFP-3, and EFP-4) were isolated from elderberry. EFP-0, EFP-1, EFP-2, EFP-3, and EFP-4 all contain arabinose, galactose, glucose, and mannose, with molecular weights of 1.7981 × 106, 7.0523 × 106, 7.7638 × 106, 4.3855 × 105, and 7.3173 × 105 Da, respectively. Structural characterization showed that the backbone of EFP-2 consisted of →4)-Manp (1→4)-β-D-Glcp (1→ and →4)-β-D-Glcp (1→5)-α-L-Araf (1→units, and T-α-L-Araf (1→ and T-β-D-Galp (1→ residues were detected by methylation analysis and NMR analysis. In addition, the MTT assay and zebrafish oxidative damage assay showed that EFP-2 had a protective effect on H2O2-damaged RAW264.7 cells in a dose-dependent manner, and zebrafish with the addition of EFP-2 would have low levels of ROS in vivo which showed significant antioxidant activity. Therefore, the results showed that the elderberry polysaccharides have antioxidant activity and can be used as potential antioxidants in functional foods