Sleep Apnea Classification Algorithm Development Using a Machine-Learning Framework and Bag-of-Features Derived from Electrocardiogram Spectrograms

Background: Heart rate variability (HRV) and electrocardiogram (ECG)-derived respiration (EDR) have been used to detect sleep apnea (SA) for decades. The present study proposes an SA-detection algorithm using a machine-learning framework and bag-of-features (BoF) derived from an ECG spectrogram. Methods: This study was verified using overnight ECG recordings from 83 subjects with an average apnea–hypopnea index (AHI) 29.63 (/h) derived from the Physionet Apnea-ECG and National Cheng Kung University Hospital Sleep Center database. The study used signal preprocessing to filter noise and artifacts, ECG time–frequency transformation using continuous wavelet transform (CWT), BoF feature generation, machine-learning classification using support vector machine (SVM), ensemble learning (EL), k-nearest neighbor (KNN) classification, and cross-validation. The time length of the spectrogram was set as 10 and 60 s to examine the required minimum spectrogram window time length to achieve satisfactory accuracy. Specific frequency bands of 0.1–50, 8–50, 0.8–10, and 0–0.8 Hz were also extracted to generate the BoF to determine the band frequency best suited for SA detection. Results: The five-fold cross-validation accuracy using the BoF derived from the ECG spectrogram with 10 and 60 s time windows were 90.5% and 91.4% for the 0.1–50 Hz and 8–50 Hz frequency bands, respectively. Conclusion: An SA-detection algorithm utilizing BoF and a machine-learning framework was successfully developed in this study with satisfactory classification accuracy and high temporal resolution.

RESEARCH OF A LATERAL REAMER BIT FOR DIGGING PLANTING HOLE IN ROCKY ABANDONED MINE AREA

In the abandoned mine area with Karst landform in China, soils are few and thin but rocks are common, traditional planting hole diggers are unequal to work in rocks for vegetation restoration. A reamer bit with variable lateral drilling radius was designed based on the PDC (polycrystalline diamond compact) bit technology and metamorphic mechanism. Two lateral camber blades with PDC teeth were installed inside the bit body, a screw mechanism was employed as the actuation and a spatial double triangle mechanism was taken for the transmission. The curve of the camber blade was specially defined thus the reaming load was decentralized to 85.7% teeth on the blade. The kinematics of the lateral reamer bit was analysed, the mapping models from the actuation to the reaming radius and speed were established. Concrete samples were reamed indoors from 240mm to 407mm in diameter, the reaming cutting load and time length were measured and analysed. The lateral reamer bit was approved with the experiment results, this study provided equipment support for digging the planting hole in rocky abandoned mine areas and also expanded the PDC bit application.

From When to When: Evaluating Naturalness of Reaction Time via Viewing Turn around Behaviors

This paper addresses the effects of visual reaction times of a turn around behavior toward touch stimulus in the context of perceived naturalness. People essentially prefer a quick and natural reaction time to interaction partners, but appropriate reaction times will change due to the kinds of partners, e.g., humans, computers, and robots. In this study, we investigate two visual reaction times in touch interaction: the time length from the touched timing to the start of a reaction behavior, and the time length of the reaction behavior. We also investigated appropriate reaction times for different beings: three robots (Sota, Nao and Pepper) and humans (male and female). We conducted a web-survey based experiment to investigate natural reaction times for robots and humans, and the results concluded that the best combinations of both reaction times are different between each robot (i.e., among Sota, Nao and Pepper) and the humans (i.e., between male and female). We also compared the effect of using the best combinations for each robot and human to prove the importance of using each appropriate reaction timing for each being. The results suggest that an appropriate reaction time combination investigated from the male model is not ideal for robots, and the combination investigated from the female model is a better choice for robots. Our study also suggests that calibrating parameters for individual robots’ behavior design would enable better performances than using parameters of robot behaviors based on observing human-human interaction, although such an approach is a typical method of robot behavior design.

The association between neutrophil–lymphocyte ratio and poor outcomes following infant cardiac surgery

Background Neutrophil–lymphocyte ratio (NLR) is a valuable indicator for evaluating inflammation and adverse outcomes after cardiac surgery. The objective of this study was to evaluate the association of perioperative NLR with clinical outcomes in infants undergoing congenital heart surgery with cardiopulmonary bypass. Methods We performed a retrospective review of 424 consecutive infants (≤ 1 year) undergoing cardiac surgery between January 2019 and September 2019. Neonates (≤ 28 days) and patients with incomplete NLR data were excluded. The study endpoint was a composite of poor outcomes after surgery. We assess the correlation between perioperative NLR and clinical outcomes. A receiver operating characteristic curve and multivariable logistic regression were applied to identify the prognosis performance of postoperative NLR for poor outcomes. Results A total of 68 (16%) infants experienced at least one of the poor outcomes. Postoperative NLR on the third day after the surgery showed the best prognostic significance (AUC = 0.763, 95%CI 0.700–0.826) among perioperative period, with a cut-off value of 2.05. Postoperative NLR was also strongly correlated with mechanical ventilation time, length of ICU and hospital stay (p < 0.001). Multivariable logistic regression revealed that elevated postoperative NLR (OR 3.722, 95%CI 1.895–7.309, p < 0.001) was an independent risk factor for poor outcomes in infants after cardiac surgery. Conclusions Postoperative NLR was correlated with increased mechanical ventilation time, length of ICU and hospital stay. Elevated postoperative NLR was an independent predictor for poor outcomes after cardiac surgery in infants.

Are women always better able to recognize faces? The unveiling role of exposure time

A longer exposure time generally improves individuals’ ability to recognize faces. The current research investigates whether this effect varies between genders and whether it is influenced by the gender of the exposed faces. Based on a set of four experimental studies, we advance our knowledge of face recognition, gender, gender distribution of exposed faces, and exposure time in three main ways. First, the results reveal that women are more likely than men to suffer from a decrease in face recognition ability due to a lower exposure time. Second, the findings show that when exposure time is short (vs. long) women recognize a larger proportion of same gender faces and also recognize a larger proportion of same gender faces as compared with the proportion of same gender faces recognized by men. Third, findings reveal that when individuals are only exposed to same gender faces, women recognize more faces than men regardless whether exposure time is short, or long. In short, the findings of this research suggest that insight into the interplay between gender and exposure time length is critical to appropriately determine human beings’ ability to recognize faces.

The Association Between Neutrophil-Lymphocyte Ratio and Poor Outcomes Following Infant Cardiac Surgery

Background: Neutrophil-lymphocyte ratio (NLR) is a valuable indicator for evaluating inflammation and adverse outcomes after cardiac surgery. The objective of this study was to evaluate the association of perioperative NLR with clinical outcomes in infants undergoing congenital heart surgery with cardiopulmonary bypass.Methods: We performed a retrospective review of 424 consecutive infants (≤ 1 year) undergoing cardiac surgery between January 2019 and September 2019. Neonates (≤ 28 days) and patients with incomplete NLR data were excluded. The study endpoint was a composite of poor outcomes after surgery. We assess the correlation between perioperative NLR and clinical outcomes. A receiver operating characteristic curve and multivariable logistic regression were applied to identify the prognosis performance of postoperative NLR for poor outcomes.Results: A total of 68 (16%) infants experienced at least one of the poor outcomes. Postoperative NLR on the third day after the surgery showed the best prognostic significance (AUC = 0.763, 95%CI 0.700-0.826) among perioperative period, with a cut-off value of 2.05. Postoperative NLR was also strongly correlated with mechanical ventilation time, length of ICU and hospital stay (p < 0.001). Multivariable logistic regression revealed that elevated postoperative NLR (OR 3.722, 95%CI 1.895-7.309, p < 0.001) was an independent risk factor for poor outcomes in infants after cardiac surgery.Conclusions: Postoperative NLR was correlated with increased mechanical ventilation time, length of ICU and hospital stay. Elevated postoperative NLR was an independent predictor for poor outcomes after cardiac surgery in infants.

802 PERIOPERATIVE AND SHORT-TERM OUTCOMES FOR PRIMARY ANTIREFLUX SURGERY: FUNDOPLICATION VS. RNY RECONSTRUCTION

Laparoscopic fundoplication is the gold standard for treatment of gastroesophageal reflux disease (GERD); however, RNY reconstruction may be an alternative option in patients with complex pathophysiology and other risk factors. This study aimed to compare perioperative and short-term outcomes between primary fundoplication and RNY reconstruction. Methods After IRB approval, a prospectively maintained esophageal surgery database was retrospectively reviewed to identify patients who underwent primary fundoplication or RNY reconstruction from September 2016 to July 2020. We retrieved perioperative outcomes (operative time, length of hospital stay, intraoperative and postoperative complications) along with GERD-Health-Related Quality of Life (HRQL) scores at annual follow-up. Results During the study period, 226 patients underwent surgery (fundoplication: 210; RNY: 16). The most common indication for RNY was severe esophageal dysmotility or morbid obesity. There was only one conversion to open surgery due to adhesions (fundoplication group). The operative time, length of hospital stay, and ICU stay were significantly lower in the fundoplication group. Rates of intraoperative (fundoplication: 3% vs RNY: 0) and postoperative complications (Clavien-Dindo ≥II) (fundoplication: 3% vs RNY: 6%) were not significantly different between groups. Both groups had a significant and similar improvement of GERD-HRQL scores 1 year after surgery (Table 1). Conclusion Primary antireflux surgery is associated with low perioperative morbidity and excellent short-term outcomes. RNY reconstruction and fundoplication have similar outcomes. More liberal use of RNY reconstruction as the primary antireflux surgery in patients at high risk of failure with fundoplication should be explored.

242 Is Iliosacral Screw Fixation Safe to Perform in a Day Surgery Unit?

Introduction Iliosacral screw (ISS) fixation is a percutaneous, fluoroscopy-guided technique which can be used to treat sacroiliac joint pain. During the covid-19 pandemic much of our elective practice has moved from the tertiary referral hospital to the local day surgery unit. We aimed to determine if this procedure is safe to perform as a day case procedure. Method Twelve patients underwent ISS between 2011-2017: 6 single ISS fixation, 4 two ISS fixation and 2 bilateral ISS fixation. All patients undergoing concurrent procedures were excluded. Mean age 44 years old (range 19-79); 58% male. Surgical time, length of stay, blood transfusion requirement, haemoglobin drop, and significant analgesic events were assessed. Results Average surgical time was 55 mins (single ISS; range 30-75 mins), 71 mins (two ipsilateral ISS; range 45-100 mins) and 105 mins (bilateral ISS; range 90-120 mins). All patients were discharged within 72 hours; 67% within 24 hours (4 single ISS, 2 two ISS, 2 bilateral ISS). There were no post-operative haemoglobin drops warranting blood transfusion and no delay to discharge due to significant analgesic events. Conclusions ISS fixation may be safe to perform in a day surgery unit due to acceptable surgical time, length of stay and complication rate. A larger sample size may be required to draw definitive conclusions.

Proactive Flexible Interval Intermittent Jamming for WAVE-Based Vehicular Networks

In this paper, we deal with the eavesdropping issue in Wireless Access in Vehicular Environments- (WAVE-) based vehicular networks. A proactive flexible interval intermittent jamming (FIJ) approach is proposed which predicts the time length T of the physical layer packet to be transmitted by the legitimate user and designs flexible jamming interval (JI) and jamming-free interval (JF) based on the predicted T . Our design prevents eavesdroppers from overhearing the information with low energy cost since the jamming signal is transmitted only within JI. Numerical analysis and simulation study validate the performance of our proactive FIJ, in terms of jamming energy cost and overhearing defense, by comparing with the existing intermittent jamming (IJ) and FIJ.