Impact of signal-to-noise ratio and contrast definition on the sensitivity assessment and benchmarking of fluorescence molecular imaging systems.

Significance: Standardization of fluorescence molecular imaging (FMI) is critical for ensuring quality control in guiding surgical procedures. To accurately evaluate system performance, two metrics, the signal-to-noise ratio (SNR) and contrast, are widely employed. However, there is currently no consensus on how these metrics can be computed. Aim: We aim to examine the impact of SNR and contrast definitions on the performance assessment of FMI systems. Approach: We quantified the SNR and contrast of six near-infrared FMI systems by imaging a multi-parametric phantom. Based on approaches commonly used in the literature, we quantified seven SNRs and four contrast values considering different background regions and/or formulas. Then, we calculated benchmarking (BM) scores and respective rank values for each system. Results: We show that the performance assessment of an FMI system changes depending on the background locations and the applied quantification method. For a single system, the different metrics can vary up to ∼ 35 dB (SNR), ∼ 8.65 a . u . (contrast), and ∼ 0.67 a . u . (BM score). Conclusions: The definition of precise guidelines for FMI performance assessment is imperative to ensure successful clinical translation of the technology. Such guidelines can also enable quality control for the already clinically approved indocyanine green-based fluorescence image-guided surgery.

Quieting the neonatal intensive care unit: A quality improvement initiative.

BACKGROUND: The neonatal intensive care unit (NICU) is vital for preterm infants but is often plagued by harmful noise levels. Excessive noise, ranging from medical equipment to conversations, poses significant health risks, including hearing impairment and neurodevelopmental issues. The American Academy of Pediatrics recommends strict sound limits to safeguard neonatal well-being. Strategies such as education, environmental modifications, and quiet hours have shown to reduce noise levels. However, up to 60% of the noises remain avoidable. High noise exposure exacerbates physiological disturbances, impacting vital functions and long-term neurological outcomes. Effective noise reduction in the NICU is crucial for promoting optimal neonatal development. AIM: To measure the sound levels in a NICU and reduce ambient sound levels by at least 10% from baseline. METHODS: A quasi-experimental quality improvement project was conducted over 4 mo in a 20-bed level 3 NICU in a tertiary care medical college. Baseline noise levels were recorded continuously using a sound level meter. The interventions included targeted education, environmental modifications, and organizational changes, and were implemented through three rapid Plan-Do-Study-Act (PDSA) cycles. Weekly feedback and monitoring were conducted, and statistical process control charts were used for analysis. The mean noise values were compared using the paired t-test. RESULTS: The baseline mean ambient noise level in the NICU was 67.8 dB, which decreased to 50.5 dB after the first cycle, and further decreased to 47.4 dB and 51.2 dB after subsequent cycles. The reduction in noise levels was 21% during the day and 28% at night, with an overall decrease of 25% from baseline. The most significant reduction occurred after the first PDSA cycle (mean difference of -17.3 dB, P < 0.01). Peak noise levels decreased from 110 dB to 88.24 dB after the intervention. CONCLUSION: A multifaceted intervention strategy reduced noise in the NICU by 25% over 4 months. The success of this initiative emphasizes the significance of comprehensive interventions for noise reduction.

Noise-Aware Active Learning to Develop High-Temperature Shape Memory Alloys with Large Latent Heat.

Shape memory alloys (SMAs) with large latent heat absorbed/released during phase transformation at elevated temperatures benefit their potential application on thermal energy storage (TES) in high temperature environment like power plants, etc. The desired alloys can be designed quickly by searching the vast component space of doped NiTi-based SMAs via data-driven method, while be challenging with the noisy experimental data. A noise-aware active learning strategy is proposed to accelerate the design of SMAs with large latent heat at elevated phase transformation temperatures based on noisy data. The optimal noise level is estimated by minimizing the model error with incorporation of a range of noise levels as noise hyper-parameters into the noise-aware Kriging model. The employment of this strategy leads to the discovery of the alloy with latent heat of -36.08 J g-1, 9.2% larger than the best value (-33.04 J g-1) in the original training dataset within another four experiments. Additionally, the alloy represents high austenite finish temperature (481.71°C) and relatively small hysteresis. This promotes the latent heat TES application of SMAs in high temperature circumstance. It is expected that the noise-aware approach can be convenient for the accelerated materials design via the data-driven method with noisy data.

Enhancing autumn greenway walking experience: Exploring the combined effects of noise and thermal environment.

The evaluation of outdoor green spaces is influenced by diverse sensory perceptions. Traffic noise and thermal conditions significantly impact greenway-walking satisfaction; their optimization is vital for improving user experience and encouraging outdoor engagement. The study examines a typical Beijing greenway during autumn, focusing on strategies to enhance the walking experience under the combined effects of noise and thermal environments through mobile measurements and surveys. The results show that: 1) The interplay between noise and thermal factors varies depending on the walking state. Upon arrival, an increase in noise significantly worsens thermal comfort; higher sound levels intensify warm thermal sensations, though this effect is not consciously perceived. Upon departure, the effect of noise on thermal perception is not obvious. In both walking states, thermal sensation significantly affects subjective noise perception, yet the trends of influence differ. Subjective noise loudness increases as thermal comfort worsens, showing significant correlation only upon departure. 2) During autumn greenway walks, acoustic factors exert a greater impact on Overall Environmental Satisfaction (OES), with subjective noise loudness being more influential than noise level, followed by air temperature (Ta). Greater noise decreases OES, while OES increases initially with Ta and then decreases. The integrated effects of noise-thermal factors on OES show significant changes. 3) To enhance the autumn greenway-walking experience, the advised parameters are A-weighted Sound Level (ASL) ≤ 59.12 dBA and 15.17 °C ≤ Ta ≤ 18.75 °C. Finally, three design strategies are proposed: reducing subjective noise loudness, differentiating design based on walking status and balancing acoustic-thermal perceptual preferences.

Exposure to aircraft noise exacerbates cardiovascular and oxidative damage in three mouse models of diabetes.

BACKGROUND: Epidemiology links noise to increased risk of metabolic diseases like diabetes and obesity. Translational studies in humans and experimental animals showed that noise causes reactive oxygen species (ROS)-mediated cardiovascular damage. The interaction between noise and diabetes, specifically potential additive adverse effects, remains to be determined. METHODS AND RESULTS: C57BL/6 mice were treated with streptozotocin (i.p. injections, 50 mg/kg/d for 5d) to induce type-1 diabetes, with S961 (subcutaneous osmotic minipumps, 0.57 mg/kg/d for 7d) or fed a high-fat diet (HFD, 20 weeks) to induce type-2 diabetes. Control and diabetic mice were exposed to aircraft noise to an average sound pressure level of 72 dB(A) for 4d. While body weight was unaffected, noise reduced insulin production in all diabetes models. The oral glucose tolerance test showed only an additive aggravation by noise in the HFD model. Noise increased blood pressure and aggravated diabetes-induced aortic, mesenteric, and cerebral arterioles endothelial dysfunction. ROS formation in cerebral arterioles, the aorta, the heart, and isolated mitochondria was consistently increased by noise in all models of diabetes. Mitochondrial respiration was impaired by diabetes and noise, however without additive effects. Noise increased ROS and caused inflammation in adipose tissue in the HFD model. RNA sequencing data and alteration of gene pathway clusters also supported additive damage by noise in the setting of diabetes. CONCLUSION: In all three models of diabetes, aircraft noise exacerbates oxidative stress, inflammation, and endothelial dysfunction in mice with pre-existing diabetes. Thus, noise may potentiate the already increased cardiovascular risk in diabetic patients.

Traffic noise significantly contributes to an increased risk of cardiometabolic diseases (including diabetes and obesity) in the general population via stress hormones, inflammation and oxidative stress, all of which contribute to impaired vascular function and high blood pressure. However, the extent to which noise affects pre-existing diabetes is not sufficiently explained, which prompted us to investigate the molecular mechanisms responsible for noise-mediated exacerbation of cardiometabolic complications in three different animal models with diabetes mellitus: Noise exposure in diabetic mice caused further impairment of insulin signalling, increased blood pressure, and damage of small and large blood vessels as well as oxidative stress in the aorta, brain, and heart.Our functional observations were supported by gene analyses indicating combined effects of noise and diabetes on gene groups related to inflammation and metabolism, suggesting a need for further studies in humans to investigate how noise impacts cardiovascular risk in vulnerable groups such as patients with diabetes.

Impact of Audio-Visual Complexity on Symptomatology of Laryngeal Dystonia: A Virtual Reality Study.

BACKGROUND: Laryngeal dystonia (LD) is an isolated focal dystonia characterized by involuntary spasms in laryngeal muscles selectively impairing speech production. Anecdotal observations reported the worsening of LD symptoms in stressful or vocally demanding situations. OBJECTIVES: To examine the impact of surrounding audio-visual complexity on LD symptomatology for a better understanding of disorder phenomenology. METHODS: We developed well-controlled virtual reality (VR) environments of real-life interpersonal communications to investigate how different levels of audio-visual complexity may impact LD symptoms. The VR experiments were conducted over five consecutive days, during which each patient experienced 10 h of 4100 experimental trials in VR with gradually increasing audio-visual complexity. Daily reports were collected about patients' voice changes, as well as their comfort, engagement, concentration, and drowsiness from using VR technology. RESULTS: After a weekly VR exposure, 82% of patients reported changes in their voice symptoms related to changes in background audio-visual complexity. Significant differences in voice symptoms were found between the first two levels of the audio-visual challenge complexity independent of study sessions or VR environments. CONCLUSION: This study demonstrated that LD symptoms are impacted by audio-visual background across various virtual realistic settings. These findings should be taken into consideration when planning behavioral experiments or evaluating the outcomes of clinical trials in these patients. Moreover, these data show that VR presents a reliable and useful technology for providing real-life assessments of the impact of various experimental settings, such as during the testing of novel therapeutic interventions in these patients. LEVEL OF EVIDENCE: Level 3 Laryngoscope, 2024.

The influence of occupational noise exposure on blood pressure and hearing loss among female workers of childbearing age.

OBJECTIVES: Women exposed to occupational noise experience adverse pregnancy outcomes. Therefore, we initiated a large, population-based, cross-sectional study to further investigate the effects of occupational noise on hearing and blood pressure among female workers of childbearing age. STUDY DESIGN AND SETTING: A total of 6981 childbearing-aged female workers were selected for this cross-sectional study. Basic characteristics of participants were analyzed by comparing the exposed and control groups. Logistic regression models were employed to calculate the odds ratios (ORs) and 95% confidences intervals (CIs) for the associations of occupational noise with levels of hearing loss and blood pressure. The associations were further explored through stratification by age and duration of noise exposure. RESULTS: Compared with participants not exposed to occupational noise, increasing years of occupational noise exposure were independently associated with an elevated risk of hypertension after adjustment of age, industry classification, enterprise size and economic type. Compared to participants not exposed to occupational noise, only the prevalence of bilateral hearing loss was significantly higher after adjustments for age, industry classification, enterprise size and economic type. Compared with those with normal hearing, the ORs and 95% CIs were 1.97 (0.95-4.07), 2.22 (1.05-4.68) and 1.29 (1.06-1.57) for bilateral, unilateral and any ear hearing loss, respectively. CONCLUSIONS: Occupational noise exposure is positively associated with both hypertension and bilateral hearing loss among female workers of childbearing age. Those exposed to occupational noise show an increased risk of hypertension after adjusting for potential confounders.

Frequency-domain patterns in foot-force line-of-action: an emergent property of standing balance control.

A recent line of work suggests that the net behavior of the foot-ground interaction force provides insight into quiet-standing-balance dynamics and control. Through human subject experiments, Boehm et al. found that the relative variations of the center of pressure and force orientation emerge as a distinct pattern in the frequency domain, termed the "intersection-point height." Subsequent empirical and simulation-based studies showed that different control strategies are reflected in the distribution of intersection-point height across frequency. To facilitate understanding of the strengths and limitations of the intersection-point height in describing the dynamics and control of standing, the present work establishes a spectral-based method that also enables derivation of a closed-form estimate of the intersection-point height from any linear model of quiet stance. This new method explained observations from prior work, including how the measure captures aspects of control and physiological noise. The analysis presented herein highlights the utility of the frequency-dependent foot-force dynamics in probing the balance controller and provides a tool for model development and validation to further our understanding of the neuromotor control of natural upright posture in humans.

Systematic review of environmental noise in neonatal intensive care units.

AIM: To systematically review the literature on noise exposure within the neonatal intensive care unit/special care nursery settings, specifically to describe: noise characteristics, sources of noise and ways of measuring noise. METHODS: Systematic searches were conducted through databases Medline, Embase and PubMed. Studies were included if they met the inclusion criteria (1) reported noise characteristics; (2) reported noise exposure measurements; (3) in the neonatal intensive care unit/ special care nursery settings. Methods and key findings were extracted from included studies. Quality analysis was done using a modified version of the Newcastle-Ottawa Scale. RESULTS: We identified 1651 studies, screened 871, reviewed 112 and included 47. All reported NICU average equivalent sound levels were consistently louder than recommended guidelines (45 dB). The most consistent association with higher sound pressure levels were noise sources grouped under people congregation. Half of the studies did not use measuring devices adhering to international sound level meter (SLM) standards. CONCLUSION: All NICUs exceeded recommended accumulative sound levels. People were the most consistent source of noise. Sound pressure levels need to be consistently measured with devices adhering to international SLM standards in future studies.

Enhancing visual seismocardiography in noisy environments with adaptive bidirectional filtering for Cardiac Health Monitoring.

BACKGROUND: Wearable sensors have revolutionized cardiac health monitoring, with Seismocardiography (SCG) at the forefront due to its non-invasive nature. However, the substantial motion artefacts have hindered the translation of SCG-based medical applications, primarily induced by walking. In contrast, our innovative technique, Adaptive Bidirectional Filtering (ABF), surpasses these challenges by refining SCG signals more effectively than any motion-induced noise. ABF leverages a noise-cancellation algorithm, operating on the benefits of the Redundant Multi-Scale Wavelet Decomposition (RMWD) and the bidirectional filtering framework, to achieve optimal signal quality. METHODOLOGY: The ABF technique is a two-stage process that diminishes the artefacts emanating from motion. The first step by RMWD is the identification of the heart-associated signals and the isolating samples with those related frequencies. Subsequently, the adaptive bidirectional filter operates in two dimensions: it uses Time-Frequency masking that eliminates temporal noise while engaging in non-negative matrix Decomposition to ensure spatial correlation and dorsoventral vibration reduction jointly. The main component that is altered from the other filters is the recursive structure that changes to the motion-adapted filter, which uses vertical axis accelerometer data to differentiate better between accurate SCG signals and motion artefacts. OUTCOME: Our empirical tests demonstrate exceptional signal improvement with the application of our ABF approach. The accuracy in heart rate estimation reached an impressive r-squared value of 0.95 at - 20 dB SNR, significantly outperforming the baseline value, which ranged from 0.1 to 0.85. The effectiveness of the motion-artifact-reduction methodology is also notable at an SNR of - 22 dB. Consequently, ECG inputs are not required. This method can be seamlessly integrated into noisy environments, enhancing ECG filtering, automatic beat detection, and rhythm interpretation processes, even in highly variable conditions. The ABF method effectively filters out up to 97% of motion-related noise components within the SCG signal from implantable devices. This advancement is poised to become an integral part of routine patient monitoring.