Sleep Quality and Poor Sleep-related Factors Among Healthcare Workers During the COVID-19 Pandemic in Vietnam

Thang Phan,Ha Phan Ai Nguyen,Cao Khoa Dang,Minh Tri Phan,Vu Thanh Nguyen,Van Tuan Le,Binh Thang Tran,Chinh Van Dang,Tinh Huu Ho,Minh Tu Nguyen,Thang Van Dinh,Van Trong Phan,Binh Thai Dang,Huynh Ho Ngo The Korean Society for Preventive Medicine 2023 예방의학회지 Vol.56 No.4

Objectives: The coronavirus disease 2019 (COVID-19) pandemic has increased the workload of healthcare workers (HCWs), impacting their health. This study aimed to assess sleep quality using the Pittsburgh Sleep Quality Index (PSQI) and identify factors associated with poor sleep among HCWs in Vietnam during the COVID-19 pandemic. Methods: In this cross-sectional study, 1000 frontline HCWs were recruited from various healthcare facilities in Vietnam between October 2021 and November 2021. Data were collected using a 3-part self-administered questionnaire, which covered demographics, sleep quality, and factors related to poor sleep. Poor sleep quality was defined as a total PSQI score of 5 or higher. Results: Participants' mean age was 33.20±6.81 years (range, 20.0-61.0), and 63.0% were women. The median work experience was 8.54±6.30 years. Approximately 6.3% had chronic comorbidities, such as hypertension and diabetes mellitus. About 59.5% were directly responsible for patient care and treatment, while 7.1% worked in tracing and sampling. A total of 73.8% reported poor sleep quality. Multivariate logistic regression revealed significant associations between poor sleep quality and the presence of chronic comorbidities (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.17 to 5.24), being a frontline HCW directly involved in patient care and treatment (OR, 1.59; 95% CI, 1.16 to 2.16), increased working hours (OR, 1.84; 95% CI,1.37 to 2.48), and a higher frequency of encountering critically ill and dying patients (OR, 1.42; 95% CI, 1.03 to 1.95). Conclusions: The high prevalence of poor sleep among HCWs in Vietnam during the COVID-19 pandemic was similar to that in other countries. Working conditions should be adjusted to improve sleep quality among this population.

Controller design of a bi-directional dc-dc converter for charge-discharge of a 3 kW PCS battery

Van Thang Do(도반탕),Chang- Soon Kim(김창순),Dinh- Vuong Le(레딘브엉),Tat- Thang Le(레덧탕),Minwon Park(박민원),In- Keun Yu(유인근) 대한전기학회 2018 대한전기학회 학술대회 논문집 Vol.2018 No.-

Green and direct functionalization of poly (ethylene glycol) grafted polymers onto single walled carbon nanotubes: Effective nanocarrier for doxorubicin delivery

Xuan Thang Cao,Maheshkumar Prakash Patil,Quoc Thang Phan,Cuong M.Q. Le,Byung-Hyun Ahn,GUN-DO KIM,임권택 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

This paper reports a green and direct functionalization of poly(ethylene glycol)-graft-[furfuryl-graft-(poly(styrene-alt-maleic anhydride))] (PEG-PSMF) on the surface of single walled carbon nanotubes (SWCNTs)in aqueous media through Diels-Alder (DA) click reaction. Firstly, novel PEG grafted, furfurylfunctionalized copolymers were prepared by RAFT polymerization followed by ring opening reactions. The functional copolymer was simply grafted on SWCNTs by DA reaction at room temperature underultrasonication. The resulting hybrid materials were characterized by 1H NMR, GPC, UV–vis, FT-IR, TGA,TEM, and DLS. The hybrid materials possessed a high drug loading capacity (DLC) of doxorubicin (DOX),which could reach up to 279.9 wt.% of DLC. Moreover, in vitro drug release profiles showed that drugrelease rate at pH 5.5 under an acidic condition of tumor cell microenvironment was much higher than atpH 7.4 of the physiological condition. MTT assays demonstrated that the hybrid materials did not haveany practical cytotoxicity against the normal HEK293 cell line, while drug loaded hybrids displayed a highantitumor activity towards HeLa cancer cells. This strategy offers a promising SWCNT-based drug carrierfor tumor-targeted chemotherapy.

Secrecy Capacity of Nakagami-m Fading Channels

Thang Van Nguyen,Hien Quoc Ngo,Hyundong Shin 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7

This paper concerns with the transmission of confidential data over Nakagami-m fading channels with three terminals-a sender, a receiver and an eavesdropper. Considering the problem of secure communications between two nodes over a Nakagami-m fading channel in the presence of eavesdropper, we derive the closed-form expressions of the ergodic secrecy capacity and outage probability for two scenarios with and without channel state information at the transmitter.

A new approach for nonlinear buckling analysis of imperfect functionally graded carbon nanotube-reinforced composite plates

Thang, P.T.,Nguyen, T.T.,Lee, J. Elsevier Science Ltd 2017 Composites. Part B, Engineering Vol.127 No.-

This paper presents an analytical approach to analyze the nonlinear static buckling of imperfect functionally graded carbon nano-reinforced composite (FG-CNTRC) plates subjected to axial compression. The material properties of the FG-CNTRC are assumed to be graded through the thickness direction according to several linear distributions of the volume fraction of carbon nanotubes. The theoretical formulations are based on the classical plate theory (Kirchhoff plate) with von Karman-type of nonlinearity and the initial geometrical imperfection. The approximate solution is developed for simply supported and freely movable boundary conditions. By applying the traditional Galerkin method and the Airy stress function, the results for the critical load are obtained in closed-form solutions, which are convenient to be used in engineering design. Some illustrative examples are also presented in details to investigate the effects of the imperfection, carbon nanotubes, and geometrical parameters on the nonlinear static behavior the plates.

Directional Orbital Angular Momentum Generator with Enhanced Vertical Emission Efficiency

Thang Q. Tran,김상인 한국광학회 2019 Current Optics and Photonics Vol.3 No.4

We propose a ring resonator-based orbital angular momentum carrying vortex beam generator design with high vertical directional emission efficiency. By adopting a vertically asymmetric grating structure in the ring resonator, optimized for enhanced vertical emission, an emission efficiency in one direction reaches as high as 78%, exceeding the 50% theoretical limit of previously designed vertically symmetric grating-assisted ring resonator-based structures.

Analysis and Design of Grid-Connected Photovoltaic Systems With Multiple-Integrated Converters and a Pseudo-DC-Link Inverter

Thang, T. V.,Thao, N. M.,Jong-Ho Jang,Joung-Hu Park IEEE 2014 IEEE transactions on industrial electronics Vol.61 No.7

<P>An architecture of multiple-integrated converter modules sharing an unfolding full-bridge inverter with a pseudo dc link (MIPs) is proposed for grid-connected photovoltaic systems in this paper. The proposed configuration can improve the power conversion, the control circuit complexity, and the cost competitiveness. The proposed MIP is composed of distributed flyback dc-dc converters (DFCs) and an unfolding full-bridge inverter with an ac filter. The DFCs can eliminate the shading effect by using the individual maximum power point tracking. In conventional flyback-type single-phase utility-interactive inverters, discontinuous conduction mode and boundary conduction mode are popular because of the inherent constant current-source characteristics more desirable for grid connection and of the simple procedures for the controller design. However, the operating mode suffers from a large current stress of the circuit components, which leads to the low power efficiency. To avoid this, the DFCs operate under continuous conduction mode that allows reduced current stresses and increased power efficiency, as well as low material cost. The current control loop of the converters employs primary-side regulation contributing to improvement of dynamics as well as the cost reduction significantly due to the elimination of the high-linearity photocoupler device. Development of a new dc-current loop that maintains the level of dc-current injection into the grid within the levels stipulated by IEEE 1547 will be dealt as well. The performance validation of the proposed design is confirmed by experimental results of a 200-W hardware prototype.</P>

A Metadata-enabled Approach for Scalable Video Streaming in Heterogeneous Networks

Thang, Truong Cong,Le, Hung T.,Nguyen, Duc V.,Pham, Anh T. Korea Multimedia Society 2015 The journal of multimedia information system Vol.2 No.1

In today's pervasive computing environments, multimedia content should be adapted to meet various conditions of network connections, terminals, and user characteristics. Scalable Video Coding (SVC) is a key solution for video communication over heterogeneous networks, where user terminals have different capabilities. This paper presents a standard-compliant approach that adapts an SVC bitstream to support multiple users. The adaptation problem is formulated as an optimization problem, focusing on the tradeoff between qualities of different spatial layers of an SVC video. Then the adaptation process is represented by standard metadata of MPEG-21, which can be solved by universal processing to enable interoperable and automatic operation. Our approach provides the users with optimal quality, a wide flexibility, and seamless adaptation. To the best of our knowledge, this is the first study that shows the adaptation tradeoff between spatial layers of a conforming SVC bitstream.

Plasma Osmolality Controls Dry Forage Intake in Large-type Goats

Thang, Tran Van,Sunagawa, Katsunori,Nagamine, Itsuki,Ogura, Go Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.8

In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to clarify whether or not increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding suppress dry forage intake. Eight large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 3 to 6 years, weighing $72.3{\pm}2.74$ kg) were used in two experiments conducted under sham feeding conditions. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 h during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, an intraruminal infusion of artificial parotid saliva (RIAPS) in the control replenished saliva lost via the esophageal fistula and an intraruminal infusion of hypertonic solution (RIHS) in the treatment was carried out in order to reproduce the effects of changing salt content due to feed entering the rumen. In experiment 2, the RIHS control was conducted in the same manner as the RIHS treatment of experiment 1. The treatment group consisted of RIHS-with an intravenous infusion of artificial mixed saliva (VIAMS) treatment that was carried out for 3 h to prevent increases in plasma osmolality during feeding. The results of the RIHS treatment in experiment 1 showed that ruminal fluid osmolality increased and then an increase in plasma osmolality was observed. This resulted in the production of thirst sensations and the reduction of cumulative dry forage intake to 43.3% (p<0.05) of the RIAPS control. The results of the RIHS-VIAMS treatment in experiment 2 indicated that ruminal fluid osmolality was the same as the RIHS control but plasma osmolality significantly decreased, and thirst level was markedly reduced. This caused a significant increase of 31.4% (p<0.05) in cumulative dry forage intake in the RIHS-VIAMS treatment compared to the RIHS control. These results indicate that increases in ruminal fluid osmolality during dry forage feeding indirectly suppresses dry forage intake by causing an increase in plasma osmolality and subsequently inducing thirst sensations. The results of the present study suggest that marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding.

Optimal Sensing Cardinality for Cognitive Radios

Thang Van Nguyen,Hyundong Shin,Win, M. Z. IEEE 2011 IEEE communications letters Vol.15 No.7

<P>This letter puts forth a proactive approach for determining the sensing cardinality (the number of subchannels to sense) in a multiband cognitive radio network with limited available block energy. Specifically, we present the sensing cardinality that maximizes the achievable block rate of the cognitive user by optimally allocating available energy to the wideband spectrum sensing and data transmission. We further derive the closed-form expression for this optimal sensing cardinality when each subchannel has the identical primary spectrum occupancy statistics.</P>