Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 46
Filtrar
1.
Artigo em Inglês | MEDLINE | ID: mdl-38758616

RESUMO

Brain-computer interfaces (BCIs) have been widely focused and extensively studied in recent years for their huge prospect of medical rehabilitation and commercial applications. Transfer learning exploits the information in the source domain and applies in another different but related domain (target domain), and is therefore introduced into the BCIs to figure out the inter-subject variances of electroencephalography (EEG) signals. In this article, a novel transfer learning method is proposed to preserve the Riemannian locality of data structure in both the source and target domains and simultaneously realize the joint distribution adaptation of both domains to enhance the effectiveness of transfer learning. Specifically, a Riemannian graph is first defined and constructed based on the Riemannian distance to represent the Riemannian geometry information. To simultaneously align the marginal and conditional distribution of source and target domains and preserve the Riemannian locality of data structure in both domains, the Riemannian graph is embedded in the joint distribution adaptation (JDA) framework and forms the proposed Riemannian locality preserving-based transfer learning (RLPTL). To validate the effect of the proposed method, it is compared with several existing methods on two open motor imagery datasets, and both multi-source domains (MSD) and single-source domains (SSD) experiments are considered. Experimental results show that the proposed method achieves the highest accuracies in MSD and SSD experiments on three datasets and outperforms eight baseline methods, which demonstrates that the proposed method creates a feasible and efficient way to realize transfer learning.

2.
Front Neurosci ; 18: 1367932, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38660227

RESUMO

Steady-state visual evoked potential brain-computer interfaces (SSVEP-BCI) have attracted significant attention due to their ease of deployment and high performance in terms of information transfer rate (ITR) and accuracy, making them a promising candidate for integration with consumer electronics devices. However, as SSVEP characteristics are directly associated with visual stimulus attributes, the influence of stereoscopic vision on SSVEP as a critical visual attribute has yet to be fully explored. Meanwhile, the promising combination of virtual reality (VR) devices and BCI applications is hampered by the significant disparity between VR environments and traditional 2D displays. This is not only due to the fact that screen-based SSVEP generally operates under static, stable conditions with simple and unvaried visual stimuli but also because conventional luminance-modulated stimuli can quickly induce visual fatigue. This study attempts to address these research gaps by designing SSVEP paradigms with stereo-related attributes and conducting a comparative analysis with the traditional 2D planar paradigm under the same VR environment. This study proposed two new paradigms: the 3D paradigm and the 3D-Blink paradigm. The 3D paradigm induces SSVEP by modulating the luminance of spherical targets, while the 3D-Blink paradigm employs modulation of the spheres' opacity instead. The results of offline 4-object selection experiments showed that the accuracy of 3D and 2D paradigm was 85.67 and 86.17% with canonical correlation analysis (CCA) and 86.17 and 91.73% with filter bank canonical correlation analysis (FBCCA), which is consistent with the reduction in the signal-to-noise ratio (SNR) of SSVEP harmonics for the 3D paradigm observed in the frequency-domain analysis. The 3D-Blink paradigm achieved 75.00% of detection accuracy and 27.02 bits/min of ITR with 0.8 seconds of stimulus time and task-related component analysis (TRCA) algorithm, demonstrating its effectiveness. These findings demonstrate that the 3D and 3D-Blink paradigms supported by VR can achieve improved user comfort and satisfactory performance, while further algorithmic optimization and feature analysis are required for the stereo-related paradigms. In conclusion, this study contributes to a deeper understanding of the impact of binocular stereoscopic vision mechanisms on SSVEP paradigms and promotes the application of SSVEP-BCI in diverse VR environments.

3.
Artigo em Inglês | MEDLINE | ID: mdl-38648157

RESUMO

As an essential cognitive function, attention has been widely studied and various indices based on EEG have been proposed for its convenience and easy availability for real-time attention monitoring. Although existing indices based on spectral power of empirical frequency bands are able to describe the attentional state in some way, the reliability still needs to be improved. This paper proposed a subject-specific attention index based on the weighted spectral power. Unlike traditional indices, the ranges of frequency bands are not empirical but obtained from subject-specific change patterns of spectral power of electroencephalograph (EEG) to overcome the great inter-subject variance. In addition, the contribution of each frequency component in the frequency band is considered different. Specifically, the ratio of power spectral density (PSD) function in attentional and inattentional state is utilized to calculate the weight to enhance the effectiveness of the proposed index. The proposed subject-specific attention index based on the weighted spectral power is evaluated on two open datasets including EEG data of a total of 44 subjects. The results of the proposed index are compared with 3 traditional attention indices using various statistical analysis methods including significance tests and distribution variance measurements. According to the experimental results, the proposed index can describe the attentional state more accurately. The proposed index respectively achieves accuracies of 86.21% and 70.00% at the 1% significance level in both the t-test and Wilcoxon rank-sum test for two datasets, which obtains improvements of 41.38% and 20.00% compared to the best result of the traditional indices. These results indicate that the proposed index provides an efficient way to measure attentional state.


Assuntos
Algoritmos , Atenção , Eletroencefalografia , Humanos , Atenção/fisiologia , Eletroencefalografia/métodos , Reprodutibilidade dos Testes , Masculino , Feminino , Adulto , Adulto Jovem
4.
Nanomaterials (Basel) ; 13(24)2023 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-38133031

RESUMO

Perovskites have been recognized as a class of promising materials for optoelectronic devices. We intentionally include excessive Cs+ cations in precursors in the synthesis of perovskite CsPbBr3 nanocrystals and investigate how the Cs+ cations influence the lattice strain in these perovskite nanocrystals. Upon light illumination, the lattice strain due to the addition of alkali metal Cs+ cations can be compensated by light-induced lattice expansion. When the Cs+ cation in precursors is about 10% excessive, the electron-phonon coupling strength can be reduced by about 70%, and the carrier cooling can be slowed down about 3.5 times in lead halide perovskite CsPbBr3 nanocrystals. This work reveals a new understanding of the role of Cs+ cations, which take the A-site in ABX3 perovskite and provide a new way to improve the performance of perovskites and their practical devices further.

5.
Artigo em Inglês | MEDLINE | ID: mdl-37917520

RESUMO

As a significant aspect of cognition, attention has been extensively studied and numerous measurements have been developed based on brain signal processing. Although existing attentional state classification methods have achieved good accuracy by extracting a variety of handcrafted features, spatial features have not been fully explored. This paper proposes an attentional state classification method based on Riemannian manifold to utilize spatial information. Based on the concept of Riemannian manifold of symmetric positive definite (SPD) matrix, the proposed method exploits the structure of covariance matrix to extract spatial features instead of using spatial filters. Specifically, Riemannian distances from intra-class Riemannian means are extracted as features for their robustness. To fully extend the potential of electroencephalograph (EEG) signal, both amplitude and phase information is utilized. In addition, to solve the variance of frequency bands, a filter bank is employed to process the signal of different frequency bands separately. Finally, features are fed into a support vector machine with a polynomial kernel to obtain classification results. The proposed attentional state classification using amplitude and phase feature extraction method based on filter bank and Riemannian manifold (AP-FBRM) method is evaluated on two open datasets including EEG data of 29 and 26 subjects. According to the experimental results, the optimal set of filter bank and the optimal technique to extract features containing both amplitude and phase information are determined. The proposed method respectively achieves accuracies of 88.06% and 80.00% and outperforms 8 baseline methods, which manifests that the proposed method creates an efficient way to recognize attentional state.


Assuntos
Interfaces Cérebro-Computador , Humanos , Algoritmos , Eletroencefalografia/métodos , Processamento de Sinais Assistido por Computador , Encéfalo
6.
Artigo em Inglês | MEDLINE | ID: mdl-38015667

RESUMO

Traditional single-modality brain-computer interface (BCI) systems are limited by their reliance on a single characteristic of brain signals. To address this issue, incorporating multiple features from EEG signals can provide robust information to enhance BCI performance. In this study, we designed and implemented a novel hybrid paradigm that combined illusion-induced visual evoked potential (IVEP) and steady-state visual evoked potential (SSVEP) with the aim of leveraging their features simultaneously to improve system efficiency. The proposed paradigm was validated through two experimental studies, which encompassed feature analysis of IVEP with a static paradigm, and performance evaluation of hybrid paradigm in comparison with the conventional SSVEP paradigm. The characteristic analysis yielded significant differences in response waveforms among different motion illusions. The performance evaluation of the hybrid BCI demonstrates the advantage of integrating illusory stimuli into the SSVEP paradigm. This integration effectively enhanced the spatio-temporal features of EEG signals, resulting in higher classification accuracy and information transfer rate (ITR) within a short time window when compared to traditional SSVEP-BCI in four-command task. Furthermore, the questionnaire results of subjective estimation revealed that proposed hybrid BCI offers less eye fatigue, and potentially higher levels of concentration, physical condition, and mental condition for users. This work first introduced the IVEP signals in hybrid BCI system that could enhance performance efficiently, which is promising to fulfill the requirements for efficiency in practical BCI control systems.


Assuntos
Interfaces Cérebro-Computador , Ilusões , Humanos , Potenciais Evocados Visuais , Eletroencefalografia/métodos , Estimulação Luminosa , Algoritmos
7.
Worldviews Evid Based Nurs ; 20(6): 593-609, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37526252

RESUMO

BACKGROUND: As pharmacotherapy often leads to adverse reactions, mind-body exercise (MBE) treatments have become a more popular option for treating depression in people living with breast cancer (BC). However, the most effective type of MBE treatment for this population remains unclear. AIMS: The aim of this systematic review and network meta-analysis (NMA) was to compare the efficacy of the different MBE modes for depression in people with BC. METHODS: A systematic search for randomized controlled trials (RCTs) from inception to March 25, 2023, was conducted in the following database: EMBASE, PubMed, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Wanfang Data, China Biology Medicine, OpenGrey, and ClinicalTrials.gov. A traditional meta-analysis was conducted using the random-effects model to directly assess the effectiveness of various MBE interventions. Stata 16.0 software was used for performing the NMA. RESULTS: The NMA was performed in 32 eligible RCTs including 2361 participants. The efficacy of MBE treatments on depression was ranked as the following: Liuzijue (surface under the cumulative ranking curve [SUCRA] = 95.4%) > Tai chi (SUCRA = 76.9%) > yoga (SUCRA = 55.0%) > Baduanjin (SUCRA = 53.9%) > Pilates (SUCRA = 38.6%) > dance (SUCRA = 30.2%) > Qigong (SUCRA = 28.1%) > control (SUCRA = 21.9%). LINKING EVIDENCE TO ACTION: Our research showed that Liuzijue and Tai chi might be the most significantly effective MBE intervention for mitigating depression among BC survivors. Healthcare professionals could consider recommending Liuzijue and Tai Chi as a complementary therapy for BC survivors who experience depression.


Assuntos
Neoplasias da Mama , Sobreviventes de Câncer , Humanos , Feminino , Metanálise em Rede , Depressão/terapia , Neoplasias da Mama/complicações , Neoplasias da Mama/terapia , Sobreviventes
8.
Micromachines (Basel) ; 14(6)2023 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-37374724

RESUMO

In this paper, a dual-polarized Huygens unit is proposed, which has a double-layer metallic pattern etched on both sides of one dielectric substrate. Induced magnetism enables the structure to support Huygens' resonance, thus obtaining nearly complete available transmission phase coverage. By optimizing the structural parameters, a better transmission performance can be achieved. When the Huygens metasurface was used for the design of a meta-lens, good radiation performance was exhibited, with a maximum gain of 31.15 dBi at 28 GHz, an aperture efficiency of 42.7% and a 3 dB gain bandwidth of 26.4 GHz to 30 GHz (12.86%). Due to its excellent radiation performance and very simple fabrication, this Huygens meta-lens has important applications in millimeter-wave communication systems.

9.
J Neural Eng ; 2023 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-36808912

RESUMO

OBJECTIVE: Visual evoked potentials (VEPs) have been commonly applied in brain-computer interfaces (BCIs) due to their satisfactory classification performance recently. However, most existing methods with flickering or oscillating stimuli will induce visual fatigue under long-term training, thus restricting the implementation of VEP-based BCIs. To address this issue, a novel paradigm adopting static motion illusion based on illusion-induced visual evoked potential (IVEP) is proposed for BCIs to enhance visual experience and practicality. APPROACH: This study explored the responses to baseline and illusion tasks including the Rotating-Tilted-Lines (RTL) illusion and Rotating-Snakes (RS) illusion. The distinguishable features were examined between different illusions by analyzing the event-related potentials (ERPs) and amplitude modulation of evoked oscillatory responses. MAIN RESULTS: The illusion stimuli elicited VEPs in an early time window encompassing a negative component (N1) from 110 to 200 ms and a positive component (P2) between 210 and 300 ms. Based on the feature analysis, a filter bank was designed to extract discriminative signals. The task-related component analysis (TRCA) was used to evaluate the binary classification task performance of the proposed method. Then the highest accuracy of 86.67% was achieved with a data length of 0.6 s. SIGNIFICANCE: The results of this study demonstrate that the static motion illusion paradigm has the feasibility of implementation and is promising for VEP-based BCI applications.

10.
Biol Res Nurs ; 25(1): 41-50, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35839096

RESUMO

OBJECTIVE: To systematically summarize the reported prediction models for hypoglycemia in patients with diabetes, compare their performance, and evaluate their applicability in clinical practice. METHODS: We selected studies according to the PRISMA, appraised studies according to the Prediction model Risk of Bias Assessment Tool (PROBAST), and extracted and synthesized the data according to the CHARMS. The databases of PubMed, Web of Science, Embase, and Cochrane Library were searched from inception to 31 October 2021 using a systematic review approach to capture all eligible studies developing and/or validating a prognostic prediction model for hypoglycemia in patients with diabetes. The risk bias and clinical applicability were assessed using the PROBAST. The meta-analysis of the performance of the prediction models were also conducted. The protocol of this study was recorded in PROSPERO (CRD42022309852). RESULTS: Sixteen studies with 22 models met the eligible criteria. The predictors with the high frequency of occurrence among all models were age, HbA1c, history of hypoglycemia, and insulin use. A meta-analysis of C-statistic was performed for 21 prediction models, and the summary C-statistic and its 95% confidence interval and prediction interval were 0.7699 (0.7299-0.8098), 0.7699 (0.5862-0.9536), respectively. Heterogeneity exists between different hypoglycemia prediction models (τ2 was 0.00734≠0). CONCLUSIONS: The existing predictive models are not recommended for widespread clinical use. A high-quality hypoglycemia screening tool should be developed in future studies.


Assuntos
Diabetes Mellitus , Humanos , Medição de Risco , Previsões
11.
Chem Sci ; 13(45): 13617-13622, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36507178

RESUMO

ortho-Alkynyl quinone methides are well-known four-atom synthons for direct [4 + n] cycloaddition in constructing useful oxa-heterocyclic compounds owing to their high reactivity as well as the thermodynamically favored aromatization nature of this process. Herein we report an operationally simple and eco-friendly protocol for the modular and regioselective access of (E)-4-(vinyl or aryl or alkynyl)iminochromenes from propargylamines and S-methylated ß-ketothioamides in the presence of FeCl3, and particularly under undried acetonitrile and air atmosphere conditions. This method exhibits a broad substrate scope and displays nice functional group compatibility, thus providing an efficient access of 3,4-disubstituted iminochromenes.

12.
Heliyon ; 8(11): e11558, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36419666

RESUMO

[This corrects the article DOI: 10.1016/j.heliyon.2022.e09616.].

13.
J Nurs Manag ; 30(8): 4251-4261, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36205051

RESUMO

AIMS: To investigate the relationship between organizational support and nurse managers' burnout and the serial multiple mediating effects of leadership and resilience. BACKGROUND: Nurse managers are at a high risk of burnout, especially during the COVID-19 pandemic. However, no research has been done to examine the associations between nurse managers' organizational support, leadership, resilience and burnout. METHODS: This cross-sectional study recruited 458 nurse managers from 13 tertiary public hospitals in Jiangsu, China. They completed the Survey of Perceived Organizational Support, the Clinical Leadership Survey, the Resilience Scale and the Maslach Burnout Inventor-Human Service Survey. The serial mediating effect of individual leadership and resilience was estimated using the structural equation modelling method via Mplus 7.0. RESULTS: There were direct and indirect effects of organizational support on burnout, controlling for work variables. Leadership and resilience serially mediate the association between organizational support and burnout (ß = -.051, 95% confidence interval: -0.093 to -0.020). CONCLUSIONS: Among nurse managers, organizational support may be sequentially associated with improved leadership first and then resilience, which in turn is related to decreased burnout. IMPLICATIONS FOR NURSING MANAGEMENT: We recommend that hospital administrators incorporate leadership, resilience and burnout assessment in the routine psychological screening of nurse managers and creatively apply the organizational interventions to decrease nurse managers' burnout.


Assuntos
Esgotamento Profissional , COVID-19 , Enfermeiros Administradores , Humanos , Liderança , Enfermeiros Administradores/psicologia , Estudos Transversais , Pandemias , COVID-19/epidemiologia , Esgotamento Profissional/etiologia , Esgotamento Profissional/prevenção & controle , Esgotamento Profissional/psicologia , Inquéritos e Questionários
14.
Heliyon ; 8(9): e09616, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36091949

RESUMO

Discover potential biomarkers of the response for anti-cancer therapies, including traditional Chinese medicine (TCM), is a critical but much different task in the field of cancer research. Based on accumulated data and sophisticated methods, multi-omics analysis provides a feasible strategy for the discovery of potential therapeutic biomarkers. Here, we screened the potential therapeutic biomarkers for anti-cancer compounds in TCM through multi-omics data analysis. Firstly, compounds in TCM were collected from the public databases. Then, the molecules that those compounds can intervene on cell lines were carefully filtered out from existing drug bioactivity datasets. Finally, multi-omics analysis including gene mutation analysis, differential expression gene analysis, copy number variation analysis and clinical survival analysis for pan-cancer were conducted to screen potential therapeutic biomarkers for compounds in TCM. 13 molecules of compounds in TCM namely ERBB2, MYC, FLT4, TEK, GLI1, TOP2A, PDE10A, SLC6A3, GPR55, TERT, EGFR, KCNA3 and HDAC4 are differentially expressed, high frequently mutated, obtain high copy number variation rate and also significant in survival, are considered as the potential therapeutic biomarkers.

15.
Eur Geriatr Med ; 13(5): 1187-1195, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36001254

RESUMO

PURPOSE: Increased physical activity maintains functional fitness and prevents aging-related declines in muscle mass for older adults. However, physical inactivity is prevalent in aging population, particularly in those living in rural areas. In this study we assessed the effectiveness of a 3-month peer support and mobile application-based walking programme on physical activity and physical function in rural older Chinese adults. METHODS: This was a cluster randomized control trial recruiting adults aged ≥ 60 years. Participants were randomized into intervention and control groups (4 clusters with 36 participants for each group). The intervention included face-to-face physical activity group sessions, peer-led walking, and mobile application-based feedback. Primary outcome was pedometer-measured daily walking steps, and secondary outcomes mainly included physical function and body composition. Both intention-to-treat and per-protocol analyses were performed. RESULTS: Of the included 72 participants (mean age 66.9 years, male 36.1%), 64 completed the study. Intention-to-treat analysis showed that after 3-month walking programme, physical activity was increased by 408 steps/day and grip strength by 1.25 kg in the intervention group compared with the control group. However, no significant outcomes were observed on gait speed, chair-rising time, or body composition. Per-protocol analysis showed similar results. Linear regression analyses showed that changes in daily steps were associated with changes in gait speed (ß = 0.63, P < 0.001) and chair-rising time (ß = - 0.31, P = 0.01). CONCLUSIONS: The 3-month peer support and mobile application-based walking programme could improve physical activity and physical function in rural older adults. TRIAL REGISTRATION: ChiCTR2000034842, registered on 2020/07/21.


Assuntos
Aplicativos Móveis , Actigrafia , Idoso , Exercício Físico , Humanos , Masculino , Pessoa de Meia-Idade , Comportamento Sedentário , Caminhada/fisiologia
16.
Sci Data ; 9(1): 465, 2022 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-35918334

RESUMO

The dataset of simultaneous 64-channel electroencephalography (EEG) and high-speed eye-tracking (ET) recordings was collected from 31 professional athletes and 43 college students during alertness behavior task (ABT) and concentration cognitive task (CCT). The CCT experiment lasting 1-2 hours included five sessions for groups of the Shooting, Archery and Modern Pentathlon elite athletes and the controls. Concentration targets included shooting target and combination target with or without 24 different directions of visual distractors and 2 types of music distractors. Meditation and Schulte Grid trainings were done as interventions. Analysis of the dataset aimed to extract effective biological markers of eye movement and EEG that can assess the concentration level of talented athletes compared with same-aged controls. Moreover, this dataset is useful for the research of related visual brain-computer interfaces.


Assuntos
Eletroencefalografia , Tecnologia de Rastreamento Ocular , Atletas , Atenção , Movimentos Oculares , Humanos
17.
Front Psychiatry ; 13: 834398, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35492685

RESUMO

Background: Although pediatric resilience plays a significant role in resisting negative moods and improving glycaemic control, little research exists regarding resilience among the parents of adolescents with Type 1 diabetes. Objective: To investigate parental resilience's correlations with parental depressive symptoms, parental diabetes distress, and pediatric glycaemic control. Methods: This cross-sectional study recruited adolescents with Type 1 diabetes and their parents from two hospitals. The parents completed questionnaires. The 10-item Connor-Davidson Resilience Scale measured resilience; the Problem Areas in Diabetes Survey-Parent Revised version measured diabetes distress; the Patient Health Questionnaire-9 measured depressive symptoms. Standard glycated hemoglobin tests were performed on the adolescents. Results: Data from 224 parents (77.2% female, Mage = 39.88 [SD = 5.02], age range = 30-56 years) of adolescents (50.9% boys, Mage = 13.54 years [SD = 2.48], age range = 10-19 years) were available. More than half (52.7%) of parents exceeded the criterion score for high resilience. Parental resilience was significantly negatively associated with parental depressive symptoms and diabetes distress. Parents from the high-resilience group reported fewer depressive symptoms than those from the low-resilience group. In multivariate regressions, greater parental resilience is consistently related to better pediatric glycaemic control beyond parental psychological risk factors. Conclusions: This study highlights the importance of parental resilience for parental mental health and glycaemic control among adolescents with Type 1 diabetes. The appropriate resilience support programme might be developed for parents, especially for those existing depressive symptoms and diabetes distress.

18.
Adv Sci (Weinh) ; 9(13): e2104788, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35261191

RESUMO

The development of in situ growth methods for the fabrication of high-quality perovskite single-crystal thin films (SCTFs) directly on hole-transport layers (HTLs) to boost the performance of optoelectronic devices is critically important. However, the fabrication of large-area high-quality SCTFs with thin thickness still remains a significant challenge due to the elusive growth mechanism of this process. In this work, the influence of three key factors on in situ growth of high-quality large-size MAPbBr3 SCTFs on HTLs is investigated. An optimal "sweet spot" is determined: low interface energy between the precursor solution and substrate, a slow heating rate, and a moderate precursor solution concentration. As a result, the as-obtained perovskite SCTFs with a thickness of 540 nm achieve a record area to thickness ratio of 1.94 × 104  mm, a record X-ray diffraction peak full width at half maximum of 0.017°, and an ultralong carrier lifetime of 1552 ns. These characteristics enable the as-obtained perovskite SCTFs to exhibit a record carrier mobility of 141 cm2 V-1 s-1 and good long-term structural stability over 360 days.


Assuntos
Compostos de Cálcio , Óxidos , Titânio , Compostos de Cálcio/química , Óxidos/química , Titânio/química
19.
Opt Express ; 30(2): 2143-2155, 2022 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-35209361

RESUMO

Based on the full wave simulation and the Maxwell stress tensor theory, we demonstrate an enhanced transverse optical gradient force acting on Rayleigh particles immersed in a simple optical field formed by two linearly polarized plane waves. The optical gradient force acting on a conventional dielectric particle can be enhanced by two orders of magnitude via coating an extremely thin silver shell, whose thickness is only about one-tenth of the dielectric core. The analytical results based on the multipole expansion theory reveal that the enhanced optical gradient force comes mostly from the interaction between the incident field and the electric quadrupole excited in the core-shell particle. It is worth noting that the force expression within the dipole approximation commonly used for Rayleigh particles is invalid in our situation, even the particle is within the Rayleigh regime. In addition, both the optical potential energy and the optical trapping stiffness for the core-shell particle exhibit a great enhancement by two orders of magnitude stronger than a conventional dielectric particle and thus is favorable to a stable optical trapping. These results may extend the application range of optical tweezers and enrich optical manipulation techniques.

20.
Korean J Intern Med ; 37(1): 230-240, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34905814

RESUMO

BACKGROUND/AIMS: Older adults are vulnerable to central obesity, while the association of changes in central fatness with risk of diabetes and metabolic control has not been investigated among this particular population. This study was aimed to address these issues. METHODS: A total of 1,815 adults aged ≥ 60 years without diabetes at baseline were followed for 4 years. Incident diabetes was ascertained based on plasma glucose, hemoglobin A1c, medical history, and/or the use of anti-diabetic drugs. Central fatness was assessed by waist circumference (WC), waist-height ratio (WHtR), and body roundness index (BRI). Logistic regression analyses were used to assess the association of changes in central fatness with risk of diabetes, along with dose-response and mediation analyses. RESULTS: During the 4-year follow-up, 177 participants developed diabetes. The risk of diabetes was increased by 42%, 41%, and 40% per 1 standard deviation increases in WC, WHtR, and BRI, respectively, in multivariable-adjusted models (all p < 0.01). Moreover, these relationships were all linearly-shaped (all pnonlinearity ≥ 0.11). Increases in WC, WHtR, and BRI correlated with increases in hemoglobin A1c, triglycerides-and-glucose index, triglycerides, white blood cell, and C-reactive protein (all p ≤ 0.04). Yet only changes in hemoglobin A1c and triglycerides-and-glucose index were identified as the possible mediators for risk of diabetes, with their mediating effect being about 35% and 21%, respectively. CONCLUSION: Increases in central fatness were related to elevated risk of diabetes, and this association might be partly explained by the worsening of glycemic control and insulin resistance in older adults.


Assuntos
Diabetes Mellitus , Análise de Mediação , Idoso , Índice de Massa Corporal , Estudos de Coortes , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/epidemiologia , Glucose , Hemoglobinas Glicadas , Humanos , Fatores de Risco , Triglicerídeos , Circunferência da Cintura/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA