Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 949
Filtrar
1.
Accid Anal Prev ; 203: 107622, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38723334

RESUMO

A lane-changing (LC) maneuver may cause the follower in the target lane (new follower) to decelerate and give up space, potentially affecting crash risk and traffic flow efficiency. In congested flow, a more aggressive LC maneuver occurs where the lane changer is partially next to the new follower and creates negative gaps, namely negative gap forced LC (NGFLC). Although NGFLC forms the foundation of sideswipe crashes, little has been done to address its impacts and the contributing factors. To tackle this issue, a total of 15,810 LC trajectory samples are extracted from three drone videos at different locations. These samples are categorized into NGFLC and normal LC groups for comparative analysis. Five commonly used conflict indicators are extended into two-dimensional to evaluate the crash risk of LC maneuver. The change of time gaps during LC maneuver are examined to quantify the impact of LC on traffic flow efficiency. We find that NGFLCs significantly increase crash risk, reflected by the number of hazardous LC events and potential crash areas compared to normal LC. Additionally, results reveal that both the lane changer and the new follower tend to maintain a larger time gap after NGFLCs. Factors including time headway, relative speed, and historical gaps in the target lane significantly affect NGFLC incidence. Once the movement of the leader in the original lane is taken into account, the prediction accuracy improves from 81% to 91%. The transferability tests indicate that the findings about the negative impact of NGFLC and the accuracy of its prediction model are consistent across different locations. These findings hold implications for driving assistance systems to better predict and mitigate NGFLCs.


Assuntos
Acidentes de Trânsito , Condução de Veículo , Acidentes de Trânsito/prevenção & controle , Acidentes de Trânsito/estatística & dados numéricos , Humanos , Segurança , Desaceleração , Planejamento Ambiental , Gravação em Vídeo
2.
Accid Anal Prev ; 203: 107640, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38759380

RESUMO

The primary objective of this study was to evaluate the performance of traffic conflict measures for real-time crash risk prediction. Drone recordings were collected from a freeway section in Nanjing, China, over a year. Twenty rear-end crashes and their associated trajectories were obtained. Vehicle trajectories preceding the crash were segmented based on different time periods to represent varying crash conditions. The Extreme Value Theory (EVT) approach combined with a block maxima sampling method was then employed to investigate the generalized extreme value (GEV) distributions of extremely risky events under non-crash and crash conditions. The prediction performance was demonstrated by the differences in GEV distributions under these two conditions. Within the proposed modeling framework, the performances of Time-to-Collision (TTC), Deceleration Rate to Avoid a Crash (DRAC), and Absolute value of Derivative of Instantaneous Acceleration (ADIA) were examined and compared. The results revealed a decreasing trend in the prediction performances as the preceding time window before a crash increased. For any given length of crash conditions, TTC consistently outperformed DRAC and ADIA. Notably, TTC's reliability in crash risk prediction became more uncertain when forecasting crashes more than 2 s in advance. This study provided the optimal thresholds for TTC and ADIA for practical application in crash early warning. The methods and results in this study have the potential to be used for crash risk assessments in autonomous vehicles.


Assuntos
Aceleração , Acidentes de Trânsito , Desaceleração , Acidentes de Trânsito/estatística & dados numéricos , Acidentes de Trânsito/prevenção & controle , Humanos , China , Medição de Risco/métodos , Condução de Veículo/estatística & dados numéricos , Fatores de Tempo , Previsões/métodos
3.
BMC Cardiovasc Disord ; 24(1): 257, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38760695

RESUMO

BACKGROUND: This study aimed to investigate the potential association between the circadian rhythm of blood pressure and deceleration capacity (DC)/acceleration capacity (AC) in patients with essential hypertension. METHODS: This study included 318 patients with essential hypertension, whether or not they were being treated with anti-hypertensive drugs, who underwent 24-hour ambulatory blood pressure monitoring (ABPM). Patients were categorized into three groups based on the percentage of nocturnal systolic blood pressure (SBP) dipping: the dipper, non-dipper and reverse dipper groups. Baseline demographic characteristics, ambulatory blood pressure monitoring parameters, Holter recordings (including DC and AC), and echocardiographic parameters were collected. RESULTS: In this study, the lowest DC values were observed in the reverse dipper group, followed by the non-dipper and dipper groups (6.46 ± 2.06 vs. 6.65 ± 1.95 vs. 8.07 ± 1.79 ms, P < .001). Additionally, the AC gradually decreased (-6.32 ± 2.02 vs. -6.55 ± 1.95 vs. -7.80 ± 1.73 ms, P < .001). There was a significant association between DC (r = .307, P < .001), AC (r=-.303, P < .001) and nocturnal SBP decline. Furthermore, DC (ß = 0.785, P = .001) was positively associated with nocturnal SBP decline, whereas AC was negatively associated with nocturnal SBP (ß = -0.753, P = .002). By multivariate logistic regression analysis, deceleration capacity [OR (95% CI): 0.705 (0.594-0.836), p < .001], and acceleration capacity [OR (95% CI): 1.357 (1.141-1.614), p = .001] were identified as independent risk factors for blood pressure nondipper status. The analysis of ROC curves revealed that the area under the curve for DC/AC in predicting the circadian rhythm of blood pressure was 0.711/0.697, with a sensitivity of 73.4%/65.1% and specificity of 66.7%/71.2%. CONCLUSIONS: Abnormal DC and AC density were correlated with a blunted decline in nighttime SBP, suggesting a potential association between the circadian rhythm of blood pressure in essential hypertension patients and autonomic nervous dysfunction.


Assuntos
Anti-Hipertensivos , Monitorização Ambulatorial da Pressão Arterial , Pressão Sanguínea , Ritmo Circadiano , Hipertensão Essencial , Frequência Cardíaca , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Hipertensão Essencial/fisiopatologia , Hipertensão Essencial/diagnóstico , Hipertensão Essencial/tratamento farmacológico , Fatores de Tempo , Anti-Hipertensivos/uso terapêutico , Idoso , Valor Preditivo dos Testes , Adulto , Fatores de Risco , Eletrocardiografia Ambulatorial , Aceleração , Desaceleração
4.
Accid Anal Prev ; 203: 107644, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38788433

RESUMO

Modern vehicles are vulnerable to cyberattacks and the consequences can be severe. While technological efforts have attempted to address the problem, the role of human drivers is understudied. This study aims to assess the effectiveness of training and warning systems on drivers' response behavior to vehicle cyberattacks. Thirty-two participants completed a driving simulator study to assess the effectiveness of training and warning system according to their velocity, deceleration events, and count of cautionary behaviors. Participants, who held a valid United States driving license and had a mean age of 20.4 years old, were equally assigned to one of four groups: control (n = 8), training-only (n = 8), warning-only (n = 8), training and warning groups (n = 8). For each drive, mixed ANOVAs were implemented on the velocity variables and Poisson regression was conducted on the normalized time with large deceleration events and cautionary behavior variables. Overall, the results suggest that drivers' response behaviors were moderately affected by the training programs and the warning messages. Most drivers who received training or warning messages responded safely and appropriately to cyberattacks, e.g., by slowing down, pulling over, or performing cautionary behaviors, but only in specific cyberattack events. Training programs show promise in improving drivers' responses toward vehicle cyberattacks, and warning messages show rather moderate improvement but can be further refined to yield consistent behavior.


Assuntos
Condução de Veículo , Simulação por Computador , Desaceleração , Humanos , Condução de Veículo/educação , Condução de Veículo/psicologia , Masculino , Feminino , Adulto Jovem , Acidentes de Trânsito/prevenção & controle , Adulto , Adolescente , Tempo de Reação , Equipamentos de Proteção , Segurança
5.
J Sports Sci ; 42(7): 638-645, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38762890

RESUMO

This study examined the effects of an 8-week horizontal speed deceleration training (HSDT) programme in combination with regular handball-specific training as compared with handball-specific training only in measures of physical fitness in male youth handball players. Thirty-nine players were randomly assigned to either an HSDT group (n = 18; 15.55 ± 0.24 years) or an active-control group (CG; n = 21; 14.59 ± 0.23 years). The results showed significant and large between-group differences at post-test in countermovement jump, change-of-direction speed, and repeated sprint ability (RSA) (all p < 0.01; d = 2.04 and 1.37, 1.39, 1.53, and 1.53 for the CMJ, 505 CoD, RSAbest, RSAaverage, and RSAtotal performances, respectively). The post-hoc-analysis demonstrated significant and large improvements in all measures of physical fitness in the HSDT group (∆2.49% to 16,25%; d = 1.01 to 1,70; all p < 0,01). The CG, however, failed to reach any significant difference in all measures of physical fitness ((∆0.31% to 1.98%; d = 0.15 to 0.22; p = 0.379; p > 0.05). To summarise, an 8-week in-season HSDT programme alongside regular handball-specific training yielded positive effects on various performance measures including jumping ability, CoD speed, and RSA, when compared to handball-specific training alone. These results highlight the potential benefits of integrating HSDT into the training regimen of youth handball athletes during the competitive season.


Assuntos
Desempenho Atlético , Condicionamento Físico Humano , Aptidão Física , Humanos , Masculino , Adolescente , Aptidão Física/fisiologia , Desempenho Atlético/fisiologia , Condicionamento Físico Humano/métodos , Desaceleração , Esportes/fisiologia , Corrida/fisiologia
6.
Accid Anal Prev ; 202: 107600, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38663272

RESUMO

In China, visual guidance systems are commonly used in tunnels to optimize the visual reference system. However, studies focusing specifically on visual guidance systems in the tunnel entrance zone are limited. Hence, a driving simulation test is performed in this study to quantitatively evaluate the effectiveness of (i) visual guidance devices at different vertical positions (pavement and roadside) and (ii) a multilayer visual guidance system for regulating driving behavior in the tunnel entrance zone. Furthermore, the characteristics of driving behavior and their effects on traffic safety in the tunnel entrance zone are examined. Data such as the vehicle position, area of interest (AOI), throttle position, steering wheel angle, and lane center offset are obtained using a driving simulation platform and an eye-tracking device. As indicators, the first fixation position (FP), starting deceleration position (DP), average throttle position (TPav), number of deceleration stages (N|DS), gradual change degree of the vehicle trajectory (G|VT), and average steering wheel angle (SWAav) are derived. The regulatory effect of visual guidance devices on driving performance is investigated. First, high-position roadside visual guidance devices effectively reduce decision urgency and significantly enhance deceleration and lane-keeping performance. Specifically, the advanced deceleration performance (AD), smooth deceleration performance (SD), trajectory gradualness (TG), and trajectory stability (TS) in the tunnel entrance zone improve by 63%, 225%, 269%, and 244%, respectively. Additionally, the roadside low-position visual guidance devices primarily target the trajectory gradualness (TG), thus resulting in improvements by 80% and 448% in the TG and TS, respectively. Meanwhile, the pavement visual guidance devices focus solely on enhancing the TS and demonstrates a relatively lower improvement rate of 99%. Finally, the synergistic effect of these visual guidance devices facilitates the multilayer visual guidance system in enhancing the deceleration and lane-keeping performance. This aids drivers in early detection and deceleration at the tunnel entrance zone, reduces the urgency of deceleration decisions, promotes smoother deceleration, and improves the gradualness and stability of trajectories.


Assuntos
Condução de Veículo , Desaceleração , Humanos , China , Simulação por Computador , Acidentes de Trânsito/prevenção & controle , Adulto , Masculino , Tecnologia de Rastreamento Ocular , Feminino , Segurança , Adulto Jovem , Planejamento Ambiental
7.
Accid Anal Prev ; 202: 107567, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38669901

RESUMO

How autonomous vehicles (AVs) communicate their intentions to vulnerable road users (e.g., pedestrians) is a concern given the rapid growth and adoption of this technology. At present, little is known about how children respond to external Human Machine Interface (eHMI) signals from AVs. The current study examined how adults and children respond to the combination of explicit (eHMI signals) and implicit information (vehicle deceleration) to guide their road-crossing decisions. Children (8- to 12-year-olds) and adults made decisions about when to cross in front of a driverless car in an immersive virtual environment. The car sometimes stopped, either abruptly or gradually (manipulated within subjects), to allow participants to cross. When yielding, the car communicated its intent via a dome light that changed from red to green and varied in its timing onset (manipulated between subjects): early eHMI onset, late eHMI onset, or control (no eHMI). As expected, we found that both children and adults waited longer to enter the roadway when vehicles decelerated abruptly than gradually. However, adults responded to the early eHMI signal by crossing sooner when the cars decelerated either gradually or abruptly compared to the control condition. Children were heavily influenced by the late eHMI signal, crossing later when the eHMI signal appeared late and the vehicle decelerated either gradually or abruptly compared to the control condition. Unlike adults, children in the control condition behaved similarly to children in the early eHMI condition by crossing before the yielding vehicle came to a stop. Together, these findings suggest that early eHMI onset may lead to riskier behavior (initiating crossing well before a gradually decelerating vehicle comes to a stop), whereas late eHMI onset may lead to safer behavior (waiting for the eHMI signal to appear before initiating crossing). Without an eHMI signal, children show a concerning overreliance on gradual vehicle deceleration to judge yielding intent.


Assuntos
Automóveis , Tomada de Decisões , Pedestres , Humanos , Criança , Masculino , Pedestres/psicologia , Feminino , Adulto , Fenômenos Biomecânicos , Desaceleração , Adulto Jovem , Condução de Veículo/psicologia , Acidentes de Trânsito/prevenção & controle , Fatores de Tempo , Realidade Virtual , Sistemas Homem-Máquina
8.
Int J Sports Physiol Perform ; 19(6): 533-544, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38561004

RESUMO

PURPOSE: This study aimed at evaluating the effect of level of competition and drill typology on loads during the preseason period in male volleyball players. METHODS: Internal (percentage of peak heart rate [HR] and summated HR zone) and external (PlayerLoad per minute, total and high accelerations per minute [tACCmin and hACCmin], decelerations per minute [tDECmin and hDECmin], and jumps per minute [tJUMPmin and hJUMPmin]) loads were monitored across a 5-week preseason period in 12 Division 1 (age: 22.5 [3.9] y; stature: 188 [6.2] cm; body mass: 85 [11.6] kg; training experience: 9.4 [4.2] y) and 12 Division 2 (age: 20.7 [2.9] y; stature: 186 [6.2] cm; body mass: 77.8 [9.6] kg; training experience: 5.6 [2.3] y) male volleyball players. Furthermore, differences in load were assessed for each drill typology (warm-up, conditioning, technical, tactical, and integral). RESULTS: No effects (P > .05) of level of competition on the internal (except for summated HR zone, P = .05) and external loads (except for tJUMPmin, P = .002) were found. Differently, drill typologies showed an effect (P < .001) on all the investigated internal- and external-load measures. The main post hoc results revealed higher (P < .05) percentage of peak HR, summated HR zone, PlayerLoad per minute, and tACCmin in warm-up and conditioning drills, while higher (P < .05) hDECmin and hJUMPmin were found in tactical and integral drills. CONCLUSIONS: These results suggest that volleyball coaches use warm-up and conditioning drills when aiming at increasing the internal loads, PlayerLoad per minute, and tACCmin, while tactical and integral drills should be preferred to enhance the number of hDECmin and hJUMPmin.


Assuntos
Aceleração , Desempenho Atlético , Comportamento Competitivo , Frequência Cardíaca , Voleibol , Humanos , Masculino , Voleibol/fisiologia , Adulto Jovem , Frequência Cardíaca/fisiologia , Comportamento Competitivo/fisiologia , Desempenho Atlético/fisiologia , Condicionamento Físico Humano/métodos , Exercício de Aquecimento/fisiologia , Desaceleração
9.
Appl Ergon ; 118: 104287, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38626670

RESUMO

Understanding driver behaviors in varied traffic scenarios is critical to the design of safe and efficient roadways and traffic control device. This research presents an analysis of driver cognitive workload, situation awareness (SA) and performance for three different scenarios, including a standard intersection and contraflow grade-separated intersections (C-GSI) and quadrant GSI (Q-GSI) with lane assignment sign manipulations. The study used a simulator-based driving experiment with application of the NASA Task Load Index and Situation Awareness Global Assessment Technique to assess the influence of the scenarios on driver behavioral responses. The findings reveal challenges for drivers navigating the C-GSI, characterized by diminished SA and elevated workload. These states were associated with behaviors such as delayed lane changes, missed opportunities for appropriate lane changes, heightened acceleration behavior within deceleration segments, and frequent speeding. In contrast, while drivers in the Q-GSI scenario faced elevated workloads, their SA remained steady, largely due to lane-specific signs facilitating early lane changes. Although the Q-GSI led to increased speed variability and slight increases in deceleration, the use of supplementary speed signage revealed a promising alternative to the S-intersection. Correlation analysis highlighted a significant relationship between mental workload and acceleration responses, indicating that increased acceleration was associated with higher mental workload. In addition, a significant negative correlation between driver perceived performance and absolute lane deviations indicated that drivers with higher self-assessed performance were more accurate in lane-keeping. The study underscores the need for GSIs and signage designs that support driver SA, manage cognitive workload to improve driver performance and increase road safety.


Assuntos
Condução de Veículo , Simulação por Computador , Planejamento Ambiental , Análise e Desempenho de Tarefas , Carga de Trabalho , Humanos , Condução de Veículo/psicologia , Masculino , Adulto , Feminino , Carga de Trabalho/psicologia , Conscientização , Adulto Jovem , Aceleração , Cognição , Desaceleração , Segurança , Pessoa de Meia-Idade
10.
ISA Trans ; 148: 397-411, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38458904

RESUMO

The acceleration and deceleration (AD) motions are the basic motion modes of robot astronauts moving in a space station. Controlling the locomotion of the robot astronaut is very challenging due to the strong nonlinearity of its complex multi-body dynamics in a gravity-free environment. However, after training, humans can move well in space stations by pushing the bulkhead, and the motion mechanism of humans is a good reference for robot astronauts. The contribution of this study is modeling the human AD motion in a microgravity environment and proposing a human-like control method for robot astronauts moving in space stations. Specifically, the movement and contact force data of the human body during AD motion were collected on an air-floating platform. Through human AD modeling analysis, the mechanism of human motion is discovered, and semi-sinusoidal primitives of contact forces are proposed for AD motion. Then, a dynamic guidance model of human AD motion is built to complete motion planning under contact constraints, which is used as the expected model for the AD control of robot astronauts. Benefiting from the force primitives, accurate and safe planning of human-like AD motion can be completed. The characteristics and mechanism of human AD motion have been analyzed from the perspective of optimization. Lastly, based on the proposed dynamic guidance model, the AD motion policy is mapped to the robot astronaut system via a system control method based on the equivalent mapping of dynamic responses (force, velocity and pose). Through comparative analysis with real human motion data and simulation results under different conditions, the proposed AD control method can achieve human-like motion efficiently and stably. Even when confronted with errors in the robot's contact velocities and inertia parameters, the method can significantly reduce the motion errors while ensuring stability.


Assuntos
Aceleração , Astronautas , Desaceleração , Robótica , Voo Espacial , Ausência de Peso , Humanos , Algoritmos , Simulação por Computador , Astronave , Movimento (Física) , Movimento/fisiologia
11.
J Sports Med Phys Fitness ; 64(5): 425-431, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38445844

RESUMO

BACKGROUND: Unpredictable stopping or deceleration tasks are crucial to prevent ACL injury. The purpose of this study was to reveal differences and relationships in kinematics during different deceleration tasks with and without anticipation. METHODS: Twenty-four collegiate athletes were recruited. Three commercial video cameras were used to capture frontal and sagittal lower-extremity kinematics. Participants were instructed to perform three deceleration tasks: 1) anticipated stopping and running backward at a point indicated previously (SRB-P); 2) anticipated stopping and running backward in front of a badminton net (SRB-N); and 3) unanticipated stopping and running backward upon random flashing of a light (SRB-U). Differences and relationships between hip, knee, and ankle kinematics at stopping (SS) and deceleration steps (DS) and the height of the great trochanter (HGT) at SS were analyzed. RESULTS: For all tasks, the knee flexion angle was less than 25° at SS. There were no significant differences in hip, knee, and ankle kinematics between tasks. HGT during SRB-U was higher than that in the other tasks at DS. Hip flexion angle at SS and DS was significantly correlated with HGT at SS. During SRB_P and SRB_N, only knee flexion angle at DS was significantly correlated with HGT at SS. CONCLUSIONS: The deceleration task in this study, SRB, causes a low knee-flexion angle at SS. The COM remained higher during unanticipated stopping, which is related only to hip flexion angle during the task. Knee flexion movement does not contribute to lowering COM during an unpredictable deceleration task.


Assuntos
Desaceleração , Humanos , Fenômenos Biomecânicos , Masculino , Feminino , Adulto Jovem , Corrida/fisiologia , Articulação do Tornozelo/fisiologia , Articulação do Joelho/fisiologia , Articulação do Quadril/fisiologia , Quadril/fisiologia , Tornozelo/fisiologia
12.
J Sports Sci ; 42(3): 263-269, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38484285

RESUMO

Horizontal deceleration technique is an underpinning factor to musculoskeletal injury risk and performance in multidirectional sport. This study primarily assessed within- and between-session reliability of biomechanical and performance-based aspects of a horizontal deceleration technique and secondarily investigated the effects of limb dominance on reliability. Fifteen participants completed four horizontal decelerations on each leg during test and retest sessions. A three-dimensional motion analysis system was used to collect kinetic and kinematic data. Completion time, ground contact time, rate of horizontal deceleration, minimum centre of mass height, peak eccentric force, impulse ratio, touchdown distance, sagittal plane foot and knee angles at initial contact, maximum sagittal plane thorax angle, and maximum knee flexion moment were assessed. Coefficients of variation (COV) and intraclass correlation coefficients (ICC) were used to assess within- and between-session reliability, respectively. Seven variables showed "great" within-session reliability bilaterally (COV ≤9.13%). ICC scores were 'excellent' (≥0.91; n = 4), or 'good' (0.76-0.89; n = 7), bilaterally. Limb dominance affected five variables; three were more reliable for the dominant leg. This horizontal deceleration task was reliable for most variables, with little effect of limb dominance on reliability. This deceleration task may be reliably used to assess and track changes in deceleration technique in healthy adults.


Assuntos
Desaceleração , Humanos , Fenômenos Biomecânicos , Masculino , Reprodutibilidade dos Testes , Feminino , Adulto Jovem , Adulto , Estudos de Tempo e Movimento , Perna (Membro)/fisiologia , Joelho/fisiologia , Pé/fisiologia , Análise e Desempenho de Tarefas
13.
J Am Heart Assoc ; 13(7): e032740, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38533972

RESUMO

BACKGROUND: Autonomic function can be measured noninvasively using heart rate variability (HRV), which indexes overall sympathovagal balance. Deceleration capacity (DC) of heart rate is a more specific metric of vagal modulation. Higher values of these measures have been associated with reduced mortality risk primarily in patients with cardiovascular disease, but their significance in community samples is less clear. METHODS AND RESULTS: This prospective twin study followed 501 members from the VET (Vietnam Era Twin) registry. At baseline, frequency domain HRV and DC were measured from 24-hour Holter ECGs. During an average 12-year follow-up, all-cause death was assessed via the National Death Index. Multivariable Cox frailty models with random effect for twin pair were used to examine the hazard ratios of death per 1-SD increase in log-transformed autonomic metrics. Both in the overall sample and comparing twins within pairs, higher values of low-frequency HRV and DC were significantly associated with lower hazards of all-cause death. In within-pair analysis, after adjusting for baseline factors, there was a 22% and 27% lower hazard of death per 1-SD increment in low-frequency HRV and DC, respectively. Higher low-frequency HRV and DC, measured during both daytime and nighttime, were associated with decreased hazard of death, but daytime measures showed numerically stronger associations. Results did not substantially vary by zygosity. CONCLUSIONS: Autonomic inflexibility, and especially vagal withdrawal, are important mechanistic pathways of general mortality risk, independent of familial and genetic factors.


Assuntos
Veteranos , Humanos , Bradicardia , Desaceleração , Eletrocardiografia Ambulatorial , Frequência Cardíaca/fisiologia , Estudos Prospectivos
14.
J Cardiovasc Electrophysiol ; 35(5): 1007-1016, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38468346

RESUMO

INTRODUCTION: Cather ablation (CA) is a well-recognized treatment alternative for atrial fibrillation (AF) patients despite more than 20% ablation-treated patients suffering from AF recurrence. The underlying mechanism of AF recurrence postablation is probably associated with high cardiac parasympathetic activity, which can be assessed with deceleration capacity (DC) of heart rate. Given that the relationship between DC and AF recurrence is still controversial, this systematic review and meta-analysis was performed to investigate the characteristics of DC in patients with and without AF recurrence, evaluating the prognostic value of DC in AF patients after CA. METHODS: A literature search was systematically performed in the Embase, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases until October 01, 2023. The observational studies reporting either the pre- and postablation DC in both recurrence and non-recurrence groups or the ratios based on DC for predicting AF recurrence were mainly included. Weighted mean differences (WMD) or odds ratios (OR) based on DC would be calculated with a random-effect model, if heterogeneity estimated with the I2 index and Q statistic was significant (I2 > 50% or p < .05); otherwise, a fixed-effect model would be utilized. RESULTS: A total of eight observational studies involving 914 AF patients treated with radiofrequency or cryoballoon ablation were included in this study. Ablation-treated patients with AF recurrence had the higher DC postablation in relation to those without recurrence (WMD, 1.00; 95% confidence interval [CI], 0.33-1.67; p < .01), which was present up to 3 months of follow-up (WMD, 1.54; 95% CI, 1.11-1.96; p < .01), whereas there was no statistical significance in DC before ablation between recurrence and non-recurrence groups (WMD, 0.34; 95% CI, -0.12 to 0.79; p = .15). The high DC postablation was a risk factor for AF recurrence in ablation-treated patients (OR, 2.17; 95% CI, 1.44-3.25; p < .01). CONCLUSION: The high DC postablation was associated with the risk of AF recurrence, suggesting that DC may act as a prognostic indicator in AF patients treated with CA.


Assuntos
Fibrilação Atrial , Ablação por Cateter , Desaceleração , Frequência Cardíaca , Valor Preditivo dos Testes , Recidiva , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Potenciais de Ação , Fibrilação Atrial/fisiopatologia , Fibrilação Atrial/cirurgia , Fibrilação Atrial/diagnóstico , Ablação por Cateter/efeitos adversos , Medição de Risco , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento
16.
Chaos ; 34(2)2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38346009

RESUMO

In this paper, we study a pattern formation in the epidermal layer of skin during tumor development and appearance of a binary surface consisting of healthy and cancer cells forming Turing patterns under external osmotic pressure. The basic methodology of introducing the external influences, for example, time-targeted drug therapy or radiation exposure, influence of electromagnetic fields, laser radiation or other tumor-targeting physical influences act differently in different phases of the cell cycle. In some cases, this can lead to a slowdown in the growth of cancer cells, and sometimes vice versa. Therefore, it is of particular interest to choose the right parameters such as starting time of external pressure, its magnitude and duration depending on the cell cycle of developing cancer cells. We propose a biologically inspired model that allows us to simulate the growth of cancer cells under conditions of osmotic pressure. We divide this growth into two phases. The first is characterized by active cell division, and the second by their growth. In this article, we introduce two types of pressure: short-term and long-term, and looked at what this leads to in different phases. We have found an interesting result, that there are some resonant points in time both in the first and second phases, when the introduction of additional pressure leads to the most significant slowdown in the growth of cancer cells.


Assuntos
Desaceleração , Neoplasias , Humanos , Pressão Osmótica , Campos Eletromagnéticos , Aceleração
17.
Hawaii J Health Soc Welf ; 83(1): 4-9, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38223462

RESUMO

American football has the highest rate of concussions in United States high school sports. Within American football, impact against the playing surface is the second-most common mechanism of injury. The objective of this study was to determine if there is a difference in impact deceleration between natural grass and synthetic turf high school football fields. A Century Body Opponent Bag (BOB) manikin was equipped with a Riddell football helmet and 3 accelerometers were placed on the forehead, apex of the head, and right ear. The manikin was dropped from a stationary position onto its front, back, and left side onto natural grass (n = 10) and synthetic turf (n = 9) outdoor football fields owned and maintained by public and private institutions on O'ahu, Hawai'i. Data was collected on 1,710 total drops. All accelerometers in forward and backward falls, and 1 accelerometer in side falls showed significantly greater impact deceleration on synthetic turf compared to the natural grass surfaces (P < .05). The results of this study provide evidence-based rationale to inform youth sports policies, particularly those aimed at injury prevention through safer playing environments and equipment.


Assuntos
Concussão Encefálica , Futebol Americano , Adolescente , Humanos , Estados Unidos , Futebol Americano/lesões , Poaceae , Desaceleração , Instituições Acadêmicas
18.
Neurosci Biobehav Rev ; 157: 105542, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38215803

RESUMO

Coordinated interactions between the central and autonomic nervous systems are crucial for survival due to the inherent propensity for human behavior to make errors. In our ever-changing environment, when individuals make mistakes, these errors can have life-threatening consequences. In response to errors, specific reactions occur in both brain activity and heart rate to detect and correct errors. Specifically, there are two brain-related indicators of error detection and awareness known as error-related negativity and error positivity. Conversely, error-related cardiac deceleration denotes a momentary slowing of heart rate following an error, signaling an autonomic response. However, what is the connection between the brain and the heart during error processing? In this review, we discuss the functional and neuroanatomical connections between the brain and heart markers of error processing, exploring the experimental conditions in which they covary. Given the current limitations of available data, future research will continue to investigate the neurobiological factors governing the brain-heart interaction, aiming to utilize them as combined markers for assessing cognitive control in healthy and pathological conditions.


Assuntos
Desaceleração , Eletroencefalografia , Humanos , Tempo de Reação/fisiologia , Encéfalo , Sistema Nervoso Autônomo/fisiologia , Desempenho Psicomotor/fisiologia , Potenciais Evocados/fisiologia
19.
Chemphyschem ; 25(7): e202300866, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38267372

RESUMO

Protein sequencing is crucial for understanding the complex mechanisms driving biological functions and is of utmost importance in molecular diagnostics and medication development. Nanopores have become an effective tool for single molecule sensing, however, the weak charge and non-uniform charge distribution of protein make capturing and sensing very challenging, which poses a significant obstacle to the development of nanopore-based protein sequencing. In this study, to facilitate capturing of the unfolded protein, highly charged peptide was employed in our simulations, we found that the velocity of unfolded peptide translocating through a hybrid nanopore composed of silicon nitride membrane and carbon nanotube is much slower compared to bare silicon nitride nanopore, it is due to the significant interaction between amino acids and the surface of carbon nanotube. Moreover, by introducing variations in the charge states at the boundaries of carbon nanotube nanopores, the competition and combination of the electrophoretic and electroosmotic flows through the nanopores could be controlled, we then successfully regulated the translocation velocity of unfolded proteins through the hybrid nanopores. The proposed hybrid nanopore effectively retards the translocation velocity of protein through it, facilitates the acquisition of ample information for accurate amino acid identification.


Assuntos
Nanoporos , Nanotubos de Carbono , Compostos de Silício , Desaceleração , Proteínas , Aminoácidos , Peptídeos
20.
J Strength Cond Res ; 38(5): e226-e234, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38231139

RESUMO

ABSTRACT: Beato, M, Youngs, A, and Costin, AJ. The analysis of physical performance during official competitions in professional English football: Do positions, game locations, and results influence players' game demands? J Strength Cond Res 38(5): e226-e234, 2024-This study aimed, first, to verify if physical parameters were different between players' positions during official matches in English professional football, and second, if the game location (H and A) or results (W, L, D) affected players' physical performance. Twenty-five male professional football players of the same team were included in this data analysis (age = 27 ± 9 years) during the 2022-23 season. Players were divided into positions: center backs, wide backs, center midfielders, attacking midfielders, and strikers. The external load parameters were distance covered, high-speed running (HSR), sprinting distance, accelerations, decelerations, and high metabolic load distance (HMLD, meters > 25.5 w·kg -1 ) that were monitored using global navigation satellite systems Apex (STATSports). Linear mixed models' analysis for positions reported a significant difference in total distance ( p = 0.011), HSR ( p < 0.001), sprinting distance ( p < 0.001), accelerations ( p = 0.003), decelerations ( p = 0.002), and HMLD ( p < 0.001). Centre backs showed the lowest physical performance in the metrics analyzed, whereas players in the other positions frequently displayed a similar physical performance. Regarding locations and results, differences were only found between locations for decelerations ( p = 0.041) and between results for HMLD ( p = 0.010). In conclusion, physical performance was influenced by players' positions, whereas game location or results seem to not affect physical performance during official competitions. Consequently, practitioners can physically prepare their players independently from the location of the match or of the possible game results, whereas specific positional training is requested to optimally prepare their players.


Assuntos
Desempenho Atlético , Comportamento Competitivo , Futebol , Humanos , Masculino , Futebol/fisiologia , Desempenho Atlético/fisiologia , Adulto , Adulto Jovem , Comportamento Competitivo/fisiologia , Corrida/fisiologia , Aceleração , Sistemas de Informação Geográfica , Desaceleração
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA