Learning Volatility Surfaces using Generative Adversarial Networks

In this paper, we propose a generative adversarial network (GAN) approach for efficiently computing volatility surfaces. The idea is to make use of the special GAN neural architecture so that on one hand, we can learn volatility surfaces from training data and on the other hand, enforce no-arbitrage conditions. In particular, the generator network is assisted in training by a discriminator that evaluates whether the generated volatility matches the target distribution. Meanwhile, our framework trains the GAN network to satisfy the no-arbitrage constraints by introducing penalties as regularization terms. The proposed GAN model allows the use of shallow networks which results in much less computational costs. In our experiments, we demonstrate the performance of the proposed method by comparing with the state-of-the-art methods for computing implied and local volatility surfaces. We show that our GAN model can outperform artificial neural network (ANN) approaches in terms of accuracy and computational time.Comment: This is a working draf

Experimental study on shear mechanical properties and damage evolution ofartificial structural plane under constant normal stiffness

To study the influence of asperity angle and normal stiffness on the shear mechanical properties of the structural plane, a direct shear test of the artificial structural plane with constant normal stiffness (CNS) was carried out using the self-developed coal rock shear seepage coupling test system. The results show that the shear stress presents a periodic oscillation attenuation trend when the asperity angles are 15° and 30°. At the end of shearing, the reduction in peak shear stress with the increase of normal stiffness is 1.78, 1.42, 1.36 and 1.27 MPa, respectively, which is gradually decreasing. While the asperity angle is 45°, the shear stress gradually tends to residual strength after reaching the peak shear stress, and there is a one-to-one correspondence between normal displacement evolution and shear stress. With the increase of the asperity angles, the shear stiffness increases gradually. With the increase of normal stiffness, the peak shear stress of structural planes with 15° and 45° asperity angles increases linearly, and when the asperity angle is 30°, it presents the characteristic of piecewise function, but the peak shear dilatancy angle gradually decreases. The failure mode of the structural plane is obtained by analyzing the mass loss before and after shearing, the proportion of debris particle size, and the evolution of three-dimensional morphology parameters. When the fluctuation angles are 15° and 45°, the failure modes are relatively single, namely wear failure and tooth cutting failure. When the fluctuation angle is 30°, the failure mode has a strong and complex dependence on the experimental conditions, mainly including tooth tip shear failure and full tooth cutting failure. By combining the three-dimensional spatial point cloud data of the structural plane with the normal displacement values at the corresponding shear displacement, a simulated cloud map of the structural plane gap width at a specific shear displacement is obtained, which analyzes the dynamic evolution process of the structural plane during the shear process and obtains its failure mechanism

Neovascularization-directed bionic eye drops for noninvasive renovation of age-related macular degeneration

The current treatment of wet age-related macular degeneration (wAMD) relies on monthly intravitreal or intravenously injection of vascular endothelial growth factor (VEGF) inhibitor or photodynamic (PDT) agents to inhibit choroidal neovascularization. However, traumatic local therapy and exogenous long-distance fundus drug delivery often lead to secondary eye damage, low treatment efficiency, and immunogenic inflammation. Herein, inspired by the natural neovascular targeting ability of endogenous low-density lipoproteins (LDL), a noninvasive bionic nano-eye-drop with enhanced ocular penetrability and lesion recognizability is developed for enabling the PDT treatment of wAMD. Verteporfin (VP) as a laser-induced PDT agent is protected inside the hydrophobic core of reconstituted LDL (rLDL) vectors. 5-carboxyfluorescein (FAM) conjugated ste-penetratin (PEN, a transmembrane peptide) is anchored on the surface of the rLDL carrier, which enabled the nanoparticles (PEN-rLDL-VP) to cross the blood-retina barrier to realizing visual therapy. Following instillation, PEN-rLDL-VP can effectively deliver VP into neovascular that overexpress LDL receptors, which can respond to laser-induced PDT. Only with a single dose of the eye-drop and laser-induced PDT, the VEGF and proinflammatory intercellular adhesion molecule-1 (ICAM-1) proteins are significantly down-regulated in vivo, which implicates the neovascular inhibition and inflammation alleviation. This study presents an attractive non-invasive strategy for the PDT of wAMD

Peritumoral Microgel Reservoir for Long-Term Light-Controlled Triple-Synergistic Treatment of Osteosarcoma with Single Ultra-Low Dose

Local minimally invasive injection of anticancer therapies is a compelling approach to maximize the utilization of drugs and reduce the systemic adverse drug effects. However, the clinical translation is still hampered by many challenges such as short residence time of therapeutic agents and the difficulty in achieving multi-modulation combination therapy. Herein, mesoporous silica-coated gold nanorods (AuNR@SiO2) core-shell nanoparticles are fabricated to facilitate drug loading while rendering them photothermally responsive. Subsequently, AuNR@SiO2 is anchored into a monodisperse photocrosslinkable gelatin (GelMA) microgel through one-step microfluidic technology. Chemotherapeutic drug doxorubicin (DOX) is loaded into AuNR@SiO2 and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is loaded in the microgel layer. The osteosarcoma targeting ligand alendronate is conjugated to AuNR@SiO2 to improve the tumor targeting. The microgel greatly improves the injectability since they can be dispersed in buffer and the injectability and degradability are adjustable by microfluidics during the fabrication. The drug release can, in turn, be modulated by multi-round light-trigger. Importantly, a single super low drug dose (1 mg kg(-1) DOX with 5 mg kg(-1) DMXAA) with peritumoral injection generates long-term therapeutic effect and significantly inhibited tumor growth in osteosarcoma bearing mice. Therefore, this nanocomposite@microgel system can act as a peritumoral reservoir for long-term effective osteosarcoma treatment

The effect of polygamy on loss of human papillomavirus detection in Senegalese women

Thesis (Master's)--University of Washington, 2021Objectives: Persistent infection with human papillomavirus (HPV) can result in premalignant cervical lesions. Women in polygamous marriage are more likely to be re-exposed to HPV. Repeated exposure to HPV antigen may lead to shorter duration of infections by boosting the immune response. This study assessed the impact of polygamy on the clearance of HPV infection and assessed whether this association varies by HIV status or coinfection with multiple HPV types.Methods: We used secondary data collected in two prospective cohort studies (between 1994-1998 and 2005-2011) conducted in Senegal, western Africa. Subjects were females aged 15 years or older, were married, were not pregnant, had an intact cervix, were HPV- positive at baseline or during 4-6 month follow-up visits, and with at least 2 follow-up visits following initial detection of HPV (n=235). The unit of analysis was each infection (288 prevalent infections and 290 incident infections). We conducted marginal Cox proportional hazard regression models to investigate the impact of polygamous marriage versus monogamous marriage on the clearance of HPV infection, adjusting for age, parity, lifetime number of sex partners, infection status (prevalent or incident), HIV status (HIV positive with   350 cells/μL CD4 count; HIV positive with < 350 cells/μL CD4 count; HIV negative) and coinfection with other HPV types. We further assessed the effect modification of HIV status and coinfection with multiple HPV types. Results: We included 289 infections that occurred among polygamously married women, and 289 infections that occurred among monogamously married women. Polygamously married subjects tended to be older, were more often HIV negative, had more children, and had a higher lifetime number of sex partners. We did not identify an association between polygamous marriage and HPV clearance (HR:0.97, 95% CI: 0.70-1.34). HIV status didn’t modify this association (p-value=0.28). We observed a non-statistically significant positive association between polygamous marriage and HPV clearance (HR: 1.47, 95% CI: 0.82-2.65) in HIV positive women with   350 cells/μL CD4 counts, but not in HIV negative women (HR: 0.84, 95% CI: 0.57-1.19) or HIV positive women with < 350 cells/μL CD4 counts (HR: 0.88, 95% CI: 0.35-2.19). Coinfection with multiple HPV types was not an effect modifier (p-value=0.97). Conclusion: We conclude that polygamous marriage wasn’t associated with HPV clearance, but there was a non-significantly positive association between marital status and HPV clearance. The potential reason for this difference may be the different sexual behavior or varied immune function among women by HIV status. This finding provides potential evidence of the re-exposure-related immune responses to HPV clearance

Seismic Behavior and Force-Displacement Characterization of Neotype Column-Slab High Piers

The seismic behavior and plasticity spreading of a neotype column-slab high pier are researched in this paper. Four scale model tests of a web slab with two boundary columns are carried out under cyclic inelastic lateral displacements simulating seismic response. The test results show that the neotype column-slab high pier has strong and stable bearing capacity, good ductility, and energy dissipation capacity. The experimental values pertaining to the spread of plasticity are derived. An approach for deriving the spread of plasticity analytically is deduced and applied to the four tests. This method accurately assesses a pier’s spread of plasticity for most ductility levels. At nearly all ductility levels, the mean difference between analytical assessments of the spread of plasticity and results from 4 large-scale tests is 12% with a 9% coefficient of variation

Experimental Study on Mechanical Properties and Stability Analysis of Structural Plane under Unloading Normal Stress

Excavation in rock induces the unloading of stress in excavation-disturbed zones and can cause the structural plane to reach shear failure due to the unloading of normal stress. Unloading normal stress tests of a regular sawtooth structural plane were conducted in this study to investigate the influence of the unloading velocities (v) and asperity angles (θ) on mechanical properties and the stability of the structural plane. The average value of normal displacement (Du1) and the shear displacement of unloading (Dsu) gradually increases with an increase in θ and Du1 accounts for 59.70%, 31.81%, and 18.60% of the height of a single asperity under different θ. However, Du2, Ds, and the unloading capacity (Δσn) gradually decreased. Moreover, Ds account for 24.52%, 11.61%, and 7.4% of the length of a single asperity, respectively. With an increase in θ and v, three-dimensional (3D) morphology parameters and normal deformation energy (Un) decreased gradually, indicating that the damage degree of the structural plane increases. The analysis of the evolution of the gap width of the structural plane at the initial point, unloading point, and instability point indicates that the greater the θ or the smaller the v, the lower would be the likelihood for the structural plane to be damaged. Concurrently, its instability is more sudden and the impact tendency is stronger