Duy Tan Nguyen

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Papers by Duy Tan Nguyen

Needle-Tipped Catheter Ablation of Papillary Muscle Results in Deeper and Larger Ablation Lesions

Journal of Cardiovascular Translational Research

Data-driven operations and supply chain management: established research clusters from 2000 to early 2020

International Journal of Production Research

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CAR T Cell Locomotion in Solid Tumor Microenvironment

Cells

The promising outcomes of chimeric antigen receptor (CAR) T cell therapy in hematologic malignanc... more The promising outcomes of chimeric antigen receptor (CAR) T cell therapy in hematologic malignancies potentiates its capability in the fight against many cancers. Nevertheless, this immunotherapy modality needs significant improvements for the treatment of solid tumors. Researchers have incrementally identified limitations and constantly pursued better CAR designs. However, even if CAR T cells are armed with optimal killer functions, they must overcome and survive suppressive barriers imposed by the tumor microenvironment (TME). In this review, we will discuss in detail the important role of TME in CAR T cell trafficking and how the intrinsic barriers contribute to an immunosuppressive phenotype and cancer progression. It is of critical importance that preclinical models can closely recapitulate the in vivo TME to better predict CAR T activity. Animal models have contributed immensely to our understanding of human diseases, but the intensive care for the animals and unreliable repre...

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ACESO: A 3D Agent-Based Simulation of the Interaction Between Immune and Tumor Cells

SIGSIM Conference on Principles of Advanced Discrete Simulation

Immunotherapy consists of assisting or augmenting the immune system to prevent or treat diseases ... more Immunotherapy consists of assisting or augmenting the immune system to prevent or treat diseases and has shown great promise in improving upon the conventional methods of treating cancer, namely radiation therapy, chemotherapy, and surgery [2]. However, conducting preclinical studies in this field can take months to years and often require costly equipment and training to execute. Researchers have used in-silico methods to reduce the time to conduct these studies, computationally exploring many different experimental configurations in a fraction of the time needed in a wet lab [1]. A common method used to describe the interaction of the immune system with tumor cells is through ordinary and partial differential equations of the evolution in the populations, but these top-down approaches often cannot capture the necessary detail required to understand the dynamics that operate at the cellular level [3]. Appropriately, studies that approach these systems from the bottom-up, particularly agent-based simulations, have shown success in capturing the dynamics of cell-to-cell interactions [4].

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3D In Vitro Platform for Cell and Explant Culture in Liquid-like Solids

Cells, 2022

Existing 3D cell models and technologies have offered tools to elevate cell culture to a more phy... more Existing 3D cell models and technologies have offered tools to elevate cell culture to a more physiologically relevant dimension. One mechanism to maintain cells cultured in 3D is by means of perfusion. However, existing perfusion technologies for cell culture require complex electronic components, intricate tubing networks, or specific laboratory protocols for each application. We have developed a cell culture platform that simply employs a pump-free suction device to enable controlled perfusion of cell culture media through a bed of granular microgels and removal of cell-secreted metabolic waste. We demonstrated the versatile application of the platform by culturing single cells and keeping tissue microexplants viable for an extended period. The human cardiomyocyte AC16 cell line cultured in our platform revealed rapid cellular spheroid formation after 48 h and ~90% viability by day 7. Notably, we were able to culture gut microexplants for more than 2 weeks as demonstrated by immu...

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Renewable Energy System Using Weather Data for Optimal Scheduling*

2018 4th International Conference on Green Technology and Sustainable Development (GTSD), 2018

There is no doubt that renewable energy (RE) is now playing a key role in our daily life and has ... more There is no doubt that renewable energy (RE) is now playing a key role in our daily life and has become more popular thanks to many advantages such as environment friendly, unlimited sources and so on, variable of applications. Obviously, the only one obstacle we must face is the dependence upon weather conditions which have been, so far, the unpredictable variants of most RE systems. Hence, in this paper, we propose a new algorithm using weather forecast and historical weather data in order to optimize performance of RE systems. Basically, this algorithm is not only making full use of weather data base but also helping us decide whether to discharge the load or have it operates on high performance at least in the next three hours [1]. We have already embedded it into our RE system combining with Darius wind turbine and photovoltaic (PV) system, the result is showed below.

ARO: Exploring the Design of Smart-Ring Interactions for Encumbered Hands

Proceedings of the 23rd International Conference on Mobile Human-Computer Interaction, 2021

Fingertip computing has seen increased interest through miniaturized smart-rings for augmenting d... more Fingertip computing has seen increased interest through miniaturized smart-rings for augmenting digital peripherals. One key advantages of such always-available input devices is the non-necessity to hold a device for interaction, as it remains affixed to a finger for access when needed. Such a wearable device makes it possible to interaction with content even when the hand is encumbered, by grasping or holding objects. Our investigation aims at understanding the properties of this fundamental smart-ring advantage. We designed a smart-ring prototype, ARO (in-Air, on-Ring, on-Object interaction), which facilitates input while grasping objects. To better identify interaction possibilities, we present the results of an elicitation study through which we grouped various forms of micro-gestures possible with ARO while holding objects under different grasp requirements. We then explored the ability for users to perform different navigation tasks (i.e. zooming and panning) using the smart-ring with encumbered hands. In our studies, users were most efficient when using either In-air or On-ring interactions, in comparisons to gestures detected On-object. Furthermore, In-air was the most preferred by our participants.

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Use of cell phone adapters is associated with reduction in disparities in remote monitoring of cardiac implantable electronic devices

Journal of Interventional Cardiac Electrophysiology, 2020

Background Remote monitoring (RM) of cardiac implantable electronic devices (CIEDs) is standard o... more Background Remote monitoring (RM) of cardiac implantable electronic devices (CIEDs) is standard of care. However, it is underutilized. In July 2012, our institution began providing cell phone adapters (CPAs) to patients free of charge following CIED implantation to improve remote transmission (RT) adherence.

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A Kinematic Collision Box Algorithm Applied for the Anti-Collision System of Offshore Drilling Vessels

Journal of Marine Science and Engineering, 2020

With the advances in technology and the automation of drilling platforms, the Anti-Collision Syst... more With the advances in technology and the automation of drilling platforms, the Anti-Collision System (ACS) has appeared as an affordable technology, which is intended to keep equipment on the drilling floor working harmoniously and to prevent the potential hazards associated with accidents. However, the specialty of the machinery on the drilling floor requires a distinguished structure for the ACS and a reliable collision-avoidance algorithm, which is not similar to any algorithm in other applications, such as automobiles and robotics. The aim of this paper is to provide a comprehension of the configuration of an ACS in an Integrated Drilling System and to develop a practical anti-collision algorithm that can be applied to the machine arrangement for an offshore drilling operation. By analyzing the motions and using kinematic parameters, such as the speed and deceleration information of drilling equipment, a kinematic collision box algorithm is developed to eliminate the limitation o...

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Letter in reply: Continuous radiofrequency ablation in scar‐based arrhythmia substrate

Journal of Cardiovascular Electrophysiology, 2020

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Continuous ablation improves lesion maturation compared with intermittent ablation strategies

Journal of Cardiovascular Electrophysiology, 2020

Background: Interrupted ablation is increasingly proposed as part of high-power short-duration ra... more Background: Interrupted ablation is increasingly proposed as part of high-power short-duration radiofrequency ablation (RFA) strategies and may also result from loss of contact from respiratory patterns or cardiac motion. To study the extent that ablation interruption affects lesions. Methods: In ex vivo and in vivo experiments, lesion characteristics and tissue temperatures were compared between continuous (group 1) and interrupted (groups 2 and 3) RFA with equal total ablation duration and contact force. Extended duration ablation lesions were also characterized from 1 to 5 minutes. Results: In the ex vivo study, continuous RFA (group 1) produced larger total lesion volumes compared with each interrupted ablation lesion group (273.8 ± 36.5 vs 205.1 ± 34.2 vs 174.3 ± 32.3 mm 3 , all P < .001). Peak temperatures for group 1 were higher at 3 and 5 mm than groups 2 and 3. In vivo, continuous ablation resulted in larger lesions, greater lesion depths, and higher tissue temperatures. Longer ablation durations created larger lesion volumes and increased lesion depths. However, after 3 minutes of ablation, the rate of lesion volume, and depth formation decreased. Conclusions: Continuous RFA delivery resulted in larger and deeper lesions with higher tissue temperatures compared with interrupted ablation. This study may have implications for highpower short duration ablation strategies, motivates strategies to reduce variations in ablation delivery, and provides an upper limit for ablation duration beyond which power delivery has diminishing returns.

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Impact of epicardial adipose tissue and catheter ablation strategy on biophysical parameters and ablation lesion characteristics

Journal of Cardiovascular Electrophysiology, 2020

Epicardial adipose (EA) tissue may limit effective radiofrequency ablation (RFA).

Forging ahead: Update on radiofrequency ablation technology and techniques

Journal of Cardiovascular Electrophysiology, 2019

Innovations in radiofrequency ablation and non-ablative techniques have led to significant advanc... more Innovations in radiofrequency ablation and non-ablative techniques have led to significant advances in addressing complex arrhythmogenic substrates for a variety of cardiac arrhythmias. Anatomical challenges, deep substrate and mid-myocardial locations may pose difficulties and decrease success rates using routine methods. In this review, we provide an update on novel radiofrequency technology and techniques including (1) high power, low duration ablation, (2) ablation facilitated by low-ionic irrigant and (3) bipolar ablation. In addition, we review emerging technologies including electroporation, needle catheter ablation and ablation with the lattice catheter.

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Bipolar radiofrequency ablation creates different lesion characteristics compared to simultaneous unipolar ablation

Journal of Cardiovascular Electrophysiology, 2019

Introduction: Both bipolar and simultaneous radiofrequency ablation (bRFA, simRFA) have been used... more Introduction: Both bipolar and simultaneous radiofrequency ablation (bRFA, simRFA) have been used to treat thick midmyocardial substrate as well as during circular, multipolar ablation between shorter distances. Objectives: We sought to evaluate the biophysical parameters of simRFA, sequential unipolar RFA (seqRFA), and bRFA. Methods: Bovine myocardium was placed in a circulating saline bath. To simulate thick substrate conditions, two open irrigated ablation catheters were oriented across from each other, with myocardium in between. Thermocouples were placed in the center, ±2 mm, of the myocardium. Unipolar ablations were performed sequentially or simultaneously at 50 W for 60 seconds and compared to bRFA using the same settings. In addition, to simulate multipolar ablation, two open irrigated ablation catheters were oriented on the same side and perpendicular to myocardium at 1, 2, and 4 mm spacing. SimRFA were performed at 15 and 25 W for 60 seconds and compared to bRFA. Results: For thicker tissue, simRFA produced similar lesion volume and depth compared to bRFA but with a lesion geometry similar to seqRFA. Unlike seqRFA and simRFA, bRFA had a necrotic core spanning the myocardium. Core depths, volumes, and temperatures were significantly greater for bRFA lesions compared to simRFA or seqRFA (Figure, P < .001). Similar results were consistent for bRFA and simRFA at shorter spacings. Conclusions: BRFA has greater core lesion temperatures, corresponding to a denser and larger necrotic core, than either simRFA or seqRFA. This may have implications for considering the optimal strategy for deep midmyocardial substrates or during multipolar ablation.

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Autofluorescence imaging for improved visualization of joint structures during arthroscopic surgery

Journal of experimental orthopaedics, 2017

The purpose of our study is to develop the arthroscopic autofluorescence imaging (AFI) system to ... more The purpose of our study is to develop the arthroscopic autofluorescence imaging (AFI) system to improve the visualization during arthroscopic surgery by real-time enhancing the contrast between joint structures with autofluorescence imaging. Its validity was evaluated around the arthroscopic anterior cruciate ligament (ACL) reconstruction, specifically improving the contrast between the femoral insertion site and its background. The feasibility of the AFI system was validated with bovine and human knees. The spectral responses of the femoral insertion site and its surrounding bone and cartilage were measured with a fluorospectrometer. A prototype of the AFI system was developed based on the spectral responses (SR) and test images of the insertion site. The accuracy was validated by evaluating the overlap between manually segmented insertion sites on the white light color images and on the corresponding spectral unmixed autofluorescence images. The final prototype of the AFI system ...

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LED Driver with TRIAC Dimming Control by Variable Switched Capacitance for Power Regulation

Journal of Power Electronics, 2015

A TRIAC dimming LED driver that can control the brightness of LED arrays for a wide range of sour... more A TRIAC dimming LED driver that can control the brightness of LED arrays for a wide range of source voltage variations is proposed in this paper. Unlike conventional PWM LED drivers, the proposed LED driver adopts a TRIAC switch, which inherently guarantees zero current switching and has been proven to be quite reliable over its long lifetime. Unlike previous TRIAC type LED drivers, the proposed LED driver is composed of an LC input filter and a variable switched capacitance, which is modulated by the TRIAC turn-on timing. Thus, the LED power regulation and dimming control, which are done by a volume resistor in the same way as the conventional TRIAC dimmers, can be simultaneously performed by the TRIAC control circuit. Because the proposed LED driver has high efficiency and a long lifetime with a high power factor (PF) and low total harmonic distortion (THD) characteristics, it is quite adequate for industrial lighting applications such as streets, factories, parking garages, and emergency stairs. A simple step-down capacitive power supply circuit composed of passive components only is also proposed, which is quite useful for providing DC power from an AC source without a bulky and heavy transformer. A prototype 60 W LED driver was implemented by the proposed design procedure and verified by simulation and experimental results, where the efficiency, PF, and THD are 92%, 0.94, and 6.3%, respectively. The LED power variation is well mitigated to below ± 2% for 190 V < V s < 250 V by using the proposed simple control circuit.

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Getting to the right left atrium: Catheter ablation of atrial fibrillation and mitral annular flutter in cor triatriatum

HeartRhythm Case Reports, 2016

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Long-Lasting and Highly Efficient TRIAC Dimming LED Driver with a Variable Switched Capacitor

Journal of Power Electronics, 2016

A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts ... more A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts a variable switched capacitor for LED dimming and LED power regulation, is proposed in this paper. The proposed LED driver is power efficient, reliable, and long lasting because of the TRIAC switch that serves as its main switch. Similar to previous TRIAC dimmers for lamps, turn-on timing of a TRIAC switch can be controlled by a volume resistor, which modulates the equivalent capacitance of the proposed variable switched capacitor. Thus, LED power regulation against source voltage variation and LED dimming control can be achieved by the proposed LED driver while meeting the global standards for power factor (PF) and total harmonic distortion (THD). The long life and high power efficiency of the proposed LED driver make it appropriate for industrial lighting applications, such as those for streets, factories, parking garages, and emergency stairs. The detailed analysis of the proposed LED driver and its design procedure are presented in this paper. A prototype of 80 W was fabricated and verified by experiments, which showed that the efficiency, PF, and THD at V s = 220 V are 93.8%, 0.95, and 22.5%, respectively; 65 W of LED dimming control was achieved with the volume resistor, and the LED power variation was well mitigated below 3.75% for 190 V < V s < 250 V.

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Effect of radiofrequency energy delivery in proximity to metallic medical device components

Heart Rhythm, 2015

BACKGROUND Radiofrequency (RF) ablation of cardiac arrhythmias is often performed in the presence... more BACKGROUND Radiofrequency (RF) ablation of cardiac arrhythmias is often performed in the presence of metallic materials in the heart. OBJECTIVES We hypothesize that metal objects in proximity to an RF ablation source can lead to ohmic heating of surrounding tissue. Furthermore, we hypothesize that insulation of the metal can mitigate this RF effect Q5. METHODS A model consisting of viable bovine myocardium or thermochromic liquid crystal medium, a circulating saline bath at 371C, and a load cell was used. A 4-mm RF ablation catheter was positioned with 10 g of force over bovine myocardium and placed in proximity to a copper wire, a defibrillator lead, and a circular mapping catheter. RF was applied at 30 W, and tissue temperatures were measured. Ablation near insulated and noninsulated esophageal temperature probes was also performed. RESULTS Ablation in proximity to metal resulted in higher temperatures. Average maximum distances for observed thermal changes to 4451C for the Ϯ lead were 5.2 Ϯ 0.3 mm and 5.7 Ϯ 0.4 mm when metal was interposed between the catheter and the ground electrode. Presence of an esophageal temperature probe increased temperatures in tissues adjacent to the probe and caused lesions remote to the ablation site. Esophageal probe insulation prevented these tissue temperature increases and injury to nontargeted tissues. CONCLUSION Effects of RF ablation are potentiated near metallic components of medical devices, leading to significant tissue heating. Further research is needed to assess the safety impact of RF in the myocardium near metallic objects, particularly esophageal temperature probes.

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Integrating demand response market into energy/reserve market: A bilevel approach

2014 Smart Grid Conference (SGC), 2014

The concept of demand response (DR) market, which recently introduced, is a comprehensive approac... more The concept of demand response (DR) market, which recently introduced, is a comprehensive approach to schedule DR. DR market is a separate market in which DR is treated as a virtual resource to be exchanged between DR buyers and sellers. The major advantage of the DR market in comparison to other DR proposals is that it allocates benefits and payments across all participants, fairly. However, there are still obstacles to its integration into the existing power markets. This paper tries to address technical and economical issues towards integrating DR market into energy/reserve markets. For this purpose, a bilevel approach is proposed for clearing joint energy/reserve and DR markets whose upper-level problem determines system requirements for reserve using N-1 contingency criteria, and whose lower-level problem clears the DR market. The resulting nonlinear bilevel programming problem is translated into an equivalent single-level mixed-integer linear programming problem by replacing the lower-level problem by its Karush-Kuhn-Tucker optimality conditions and converting a number of nonlinearities to linear equivalents using some well-known techniques. Finally, a simple case study is used to verify the efficiency of the proposed approach.

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