Core Index Research Articles

Optical Fiber Coupler Analysis Using Daubechies Wavelets

Abstract This article presents the theoretical analysis of a signal coupling between a proposed Photonic Crystal Fiber (PCF) and a Conventional Fiber with Step Index (CFSI) system. In this analysis, the Finite Element Method (FEM) and Beam Propagation Method (BPM) are applied together with Daubechies wavelets as basis function and described in the mathematical formulation. The simulations were performed casting the PCF signal into CFSI core using the PCF refractive index. For simulation purposes, the cladding material refractive index was set as 1.5% lower than the core index. The application of Daubechies wavelets as basis functions in BPM analysis presented insertion loss around 3.8% during the fiber coupling.

Construction and confirmatory factor analysis of the core cognitive ability index system of ship C2 system operators.

BackgroundCognitive ability refers to the ability to receive, process, store, and extract information. It is the most important psychological condition for people to successfully complete activities. Previous studies have shown that the design of the human-computer interface of the command and control system cannot exceed the cognitive ability of the operator of the command and control system, and it must match the cognitive ability of the operator in order to reduce the mental load intensity, and improve the accuracy, timeliness and work efficiency. However, previous researchers in the field of cognitive science have not put forward a core index system that can represent the cognitive ability of ship command and control system operators and the importance of each index, and there are few achievements that can be used for reference.ObjectiveTo explore the core index system of cognitive ability that affecting the cognitive process of command and control system operators, and to verify the index system.MethodsBased on the classic O*NET questionnaire, two indexes of O*NET were revised, three indexes of response ability were added, and then a questionnaire on the importance evaluation of cognitive abilities index was formed. The questionnaire includes 24 indexes in six aspects: verbal abilities, idea generation and reasoning abilities, quantitative abilities, visual perception abilities, mnemonic and attentive abilities, and response abilities. The cognitive ability importance evaluation data of 202 people from different positions in the ship command and control system were collected. These data reflect the overall level of cognitive ability of operators in the whole ship command and control field.ResultsThe data analysis results show that: firstly, the most important cognitive abilities affecting command and control system operators were visual perception abilities, mnemonic and attentive abilities, and response abilities. Secondly, the results of confirmatory factor analysis show that CMIN/DF, GFI, CFI, TLI, RMSEA, RMR and other indicators used in the model test all meet the requirements. The model has a good fitting degree, and the overall index extraction method is feasible. Thirdly, the independence T test results show that for beginners and experienced experts, there is a significant difference in the important evaluation of mnemonic and attentive abilities, while there is no significant difference in the important evaluation of response and visual perception abilities. Fourthly, the results of Bi-group confirmatory factor analysis experiment show that the structural model has good stability and factor invariance.ConclusionsThrough the research of this paper, the index system which can express the core cognitive ability of the commander of command and control system is successfully constructed, and the index system has been fully verified by mathematics. The 3 abilities and 10 indexes in the index system are closely related to the work tasks of operators, which also reflects the correctness of our construction results to a certain extent. According to the results of data analysis, there are differences between assistant commanders and professional commanders in the evaluation of the importance of some indexes, which reflects the importance of working age and experience to the promotion of position skills. The results of this research are of great significance for the subsequent acquisition of cognitive ability data and assessment of post cognitive ability of command and control system operators.

Research on the Effect of Awards and Grants to Improve the Ability of Scientific Research after 2014 in China

The National Graduate Education Comprehensive Fees Policy has been in operation for more than five years since the fall semester of 2014, which is long enough to evaluate the effectiveness of the policy. Base on the existing research results, this paper proposes to adopt the core index of graduate students' scientific research ability—the level and quantity of published papers to evaluate the implementation effect of this policy, take GF University as an example to analyze the construction of the university's award and scholarship system, and make quantitative analysis of the academic graduate students' published papers. It finds that the implementation effect of scholarship system is not obvious. Therefore, this paper analyzes the reasons and puts forward the relevant countermeasures.

Experimental investigation on surface functional indices in Ultrasonic Elliptical Vibration Cutting of C45 carbon steel

The tribological performance of a machined surface is greatly influenced by the quality and reliability of manufacturing processes employed in its creation. In the present study, an attempt has been made to investigate the effects of various cutting parameters which include cutting speed, feed rate, depth of cut, and ultrasonic vibration amplitude on surface tribological characteristics of C45 carbon steel while employing surface functional indices, namely, Surface bearing index (Sbi), Core fluid retention index (Sci), and Valley fluid retention index (Svi). Ultrasonic elliptical vibration-assisted turning (UEVT) and conventional turning (CT) experiments were carried out to comparatively assess the performance of both cutting methods in terms of the surface functional parameters’ response. The observed variations of the surface functional indices under the influence of the investigated cutting parameters were critically analyzed, and a detailed comparative discussion based on the surface generation mechanisms of both cutting methods is presented. The results obtained from the 3D surface measurement revealed that the variation trends of the surface functional indices in both processing techniques are relatively the same and the UEVC method was found to have higher potential of improving the overall tribological properties of the machined surface compared with the CC method.

Core Stability Index for Healthy Young Sri Lankan Population

Core Stability Index for Healthy Young Sri Lankan Population

Development of the "Core Yellow Flags Index" (CYFI) as a brief instrument for the assessment of key psychological factors in patients undergoing spine surgery.

Depression, anxiety, catastrophising, and fear-avoidance beliefs are key "yellow flags" (YFs) that predict a poor outcome in back patients. Most surgeons acknowledge the importance of YFs but have difficulty assessing them due to the complexity of the instruments used for their measurement and time constraints during consultations. We performed a secondary analysis of existing questionnaire data to develop a brief tool to enable the systematic evaluation of YFs and then tested it in clinical practice. The following questionnaire datasets were available from a total of 932 secondary/tertiary care patients (61 ± 16years; 51% female): pain catastrophising (N = 347); ZUNG depression (N = 453); Hospital Anxiety and Depression Scale (anxiety subscale) (N = 308); fear-avoidance beliefs (N = 761). The single item that best represented the full-scale score was identified, to form the 4-item "Core Yellow Flags Index" (CYFI). 2422 patients (64 ± 16years; 54% female) completed CYFI and a Core Outcome Measures Index (COMI) before lumbar spine surgery, and a COMI 3 and 12months later (FU). The item-total correlation for each item with its full-length questionnaire was: 0.77 (catastrophising), 0.67 (depression), 0.69 (anxiety), 0.68 (fear-avoidance beliefs). Cronbach's α for the CYFI was 0.79. Structural equation modelling showed CYFI uniquely explained variance (p < 0.001) in COMI at both the 3- and 12-month FUs (β = 0.11 (women), 0.24 (men); and β = 0.13 (women), β = 0.14 (men), respectively). The 4-item CYFI proved to be a simple, practicable tool for routinely assessing key psychological attributes in spine surgery patients and made a relevant contribution in predicting postoperative outcome. CYFI's items were similar to those in the "STarT Back screening tool" used in primary care to triage patients into treatment pathways, further substantiating its validity. Wider use of CYFI may help improve the accuracy of predictive models derived using spine registry data.

The Analysis of Social Support Level in Foster Families in the Context of Their Leisure Time Activities

The objective of this study is to investigate whether there is a correlation between family social support and leisure time activities among adopted children in foster families. It has been assumed that the main factors determining leisure activities in foster families are social family ties, manifested in the form of a strong social support. The Multidimensional Scale of Perceived Social Support (MSPSS) has been used to measure the perception of support and only the first, out of three, family-related source was applied in the research. The study has been conducted from a youth perspective in the context of family leisure and family support and it has tested the types of leisure activities which the foster children and their parents participated in – core and balance. The study group consisting of youth aged 10-21 coming from the city of Poznan and its neighbouring areas. The results show that there is a correlation between family social support at all its levels (low, medium and high) and low/high core index levels both in girls and boys. These findings indicate that, from a youth perspective, core rather than balance family leisure involvement has a stronger relationship with family social support. There is a further need for experimental design in the form of an interventional program in order to effectively scan the casual effects of family support. The findings also suggest that further research is necessary to investigate the correlation between the foster families and individual leisure time activates undertaken by the adopted children.

Side-Polished Optical Fiber Structure for Sodium Nitrate Sensor

Side-polished optical fiber has long been used to build fiber sensors in a range of applications. In this work, we demonstrate a biochemical sensor application leading to sodium nitrate solutions enhanced by the interaction of multi-walled carbon nanotubes (MWCNTs) with evanescent field of propagating light in a side-polished optical fiber. Insertion loss of this sensor was estimated to be around 5 dB, which is quite high and close to the core index of the polished fiber. The influence of MWCNTs film, particularly on its sensitivity to sodium nitrate, was investigated by coating single drop of MWCNTs on a side-polished single mode fiber. It is observed the improvement of sensitivity with MWCNTs coated side-polished optical fiber has reached 0.125 dBm/°C near the resonant wavelength of 1550 nm. The experimental results clearly verify the present of MWCNTs on side-polished optical fiber has slightly influence the performance of the fiber. The output power values and shifting of the spectral positions were observed during the sensor tests by exposure of the sodium nitrate solutions with increasing concentration from 1 to 7%.

Analysis of status quo of RCT outcome indexes in treatment of acute ischemic stroke with traditional Chinese medicine

The purpose of this study was to evaluate the selection situation of outcome indexes in randomized controlled trials of traditional Chinese medicine(TCM) in the treatment of acute ischemic stroke and to provide suggestions for future research. In this study, four Chinese databases and three English databases were searched from January 2017 to June 2019. The randomized controlled trials of traditional Chinese medicine in the treatment of ischemic stroke were selected according to the pre-established selection criteria. Cochrane bias risk assessment tool was used to evaluate the quality of the included studies. A total of 20 651 related articles were searched, and 11 662 ones were left after eliminating the repetitions. Finally, 42 articles were included, including 36 articles in Chinese and 6 articles in English, 40 randomized controlled trials and 2 registration schemes of randomized controlled trials. The results showed that the outcome indexes of 42 randomized controlled trials were mainly divided into seven categories, that is clinical outcome index, blood biochemical index, mental state evaluation index, cerebral hemodynamics index, index of evaluating the degree of carotid artery stenosis, safety indicators and other indicators. The blood biochemical index was the one with highest frequency, followed by the clinical outcome index. TCM syndrome score was used as an indicator of curative outcome in 17 studies. After the analysis, it was found that there were many problems in selecting the outcome indexes for the randomized controlled trials of traditional Chinese medicine in the treatment of cerebral apoplexy. For example, the end point index and hard index were rarely selected as the main outcome indicators, and the vast majority of them were intermediate alternative indexes; recognized curative effect could not be obtained; there were too many kinds of outcome indicators and excessive heterogeneity, hindering the promotion of superior treatment measures of traditional Chinese medicine in clinical practice. Therefore, we should draw lessons from the establishment method of the international core index outcome index set, construct the core index outcome index set of traditional Chinese medicine in the treatment of ischemic stroke, and develop the outcome index set which accords with the curative effect characteristics of traditional Chinese medicine treatment mea-sures to solve the problems effectively.

Physiologic requirement for iron in pregnant women, assessed using the stable isotope tracer technique

BackgroundKnowledge of the physiologic requirement for iron, the core index for the formulation of a dietary reference intake (DRI), is of great importance for the health of a pregnant woman and her fetus, and can help a mother accurately plan her iron supplementation. However, direct measurements of the physiologic requirement for iron during pregnancy are still lacking.MethodEleven women of reproductive age from Hebei Province, China, who planned to become pregnant in the near future, were enrolled between January and March 2015 and included in the final analysis. Subjects participated in a 2-week metabolic trial in which they consumed 50 mg of the stable isotope 58Fe, and were then followed for ~ 2 years. The abundance of 58Fe and the total iron concentration in the circulation were measured using Multi-collector Inductively-Coupled Plasma Mass Spectrometry and Atomic Absorption Spectroscopy, respectively. The physiologic requirement for iron during pregnancy was then calculated by the formula derived from our previously published work.ResultsThe mean physiologic requirement for iron in the 11 subjects, across their entire pregnancies, was 3.05 mg.d− 1 in total and 44.0 μg.kg− 1.d− 1 after adjustment for body mass. The physiologic requirements for iron in the first, second, and third trimesters were 2.04 mg.d− 1, 3.26 mg.d− 1, and 4.13 mg.d− 1, respectively. When adjusted for body mass, the physiologic requirements for iron in different trimesters were 32.3 μg.kg− 1.d− 1, 46.9 μg.kg− 1.d− 1, and 55.7 μg.kg− 1.d− 1, respectively.ConclusionWe preliminarily explored the physiologic requirement for iron in pregnant women. The data demonstrated that pregnant women needed about twice iron than non-pregnant women. This research may be helpful for the design of future studies and the modification of iron DRIs.Trial registrationChiCTR, ChiCTR-OCH-14004302. Registered 14 February 2014, http://www.chictr.org.cn/showproj.aspx?proj=5267

Cross-cultural adaptation and validation of the Slovenian version of the Core outcome measures index for low back pain

BackgroundTo conduct a cross-cultural adaptation and validation of the Core Outcome Measures Index (COMI) in the Slovenian language, for use in patients with low back pain.MethodsThe English version of COMI was translated into Slovene following established guidelines. Three hundred fifty-three patients with chronic low back pain were recruited from the Orthopedic clinic department of a tertiary care teaching institution. Data quality, construct validity, responsiveness, and test-retest reliability of the COMI were assessed.ResultsThe questionnaire was generally well accepted with no missing values. The majority of items exhibited only mild ceiling effects (below 20.0%) and somewhat more prominent floor effects, which were similar to previous studies (4.5–78.8%). Correlations with Oswestry Disability Index (ODI) were high (ρ = 0.76 between overall COMI and ODI scores), suggesting that the Slovene version of COMI had high construct validity. Additionally, the Slovene version of COMI successfully captured surgical patients’ improvement in their low back problem after surgery (overall COMI score change: Z = − 9.34, p < .001, r = − 0.53) and showed acceptable test-retest reliability (ICC = 0.86).ConclusionsThe Slovene version of COMI showed good psychometric properties, comparable to those of previously tested language versions. It represents a valuable instrument for the use in future domestic and multicenter clinical studies.

Core Decomposition in Multilayer Networks

Multilayer networks are a powerful paradigm to model complex systems, where multiple relations occur between the same entities. Despite the keen interest in a variety of tasks, algorithms, and analyses in this type of network, the problem of extracting dense subgraphs has remained largely unexplored so far. As a first step in this direction, in this work, we study the problem of core decomposition of a multilayer network . Unlike the single-layer counterpart in which cores are all nested into one another and can be computed in linear time, the multilayer context is much more challenging as no total order exists among multilayer cores; rather, they form a lattice whose size is exponential in the number of layers. In this setting, we devise three algorithms, which differ in the way they visit the core lattice and in their pruning techniques. We assess time and space efficiency of the three algorithms on a large variety of real-world multilayer networks. We then move a step forward and study the problem of extracting the inner-most (also known as maximal ) cores, i.e., the cores that are not dominated by any other core in terms of their core index in all the layers. inner-most cores are typically orders of magnitude less than all the cores. Motivated by this, we devise an algorithm that effectively exploits the maximality property and extracts inner-most cores directly, without first computing a complete decomposition. This allows for a consistent speed up over a naïve method that simply filters out non-inner-most ones from all the cores. Finally, we showcase the multilayer core-decomposition tool in a variety of scenarios and problems. We start by considering the problem of densest-subgraph extraction in multilayer networks . We introduce a definition of multilayer densest subgraph that tradesoff between high density and number of layers in which the high density holds, and exploit multilayer core decomposition to approximate this problem with quality guarantees. As further applications, we show how to utilize multilayer core decomposition to speed-up the extraction of frequent cross-graph quasi-cliques and to generalize the community-search problem to the multilayer setting.

Design of Single Mode Fiber for Optical Communications

In this work, a step-index fiber with core index and cladding index has been designed. Single-mode operation can be obtained by using a fiber with core diameters 4–13 µm operating at a wavelength of 1.31 µm and by 4–15 µm at 1.55 µm. The fundamental fiber mode properties such as phase constant, effective refractive index, mode radius, effective mode area and the power in the core were calculated. Distributions of the intensity and the amplitude were shown.

Diagnostic accuracy of non-invasive methods detecting clinically significant portal hypertension in liver cirrhosis: a systematic review and meta-analysis.

We attempted to investigate non-invasive techniques and their diagnostic performances for evaluating clinically significant portal hypertension. The systematic search was performed on PubMed, Embase, Scopus, and Web of Science TM core index databases before 13 December 2018 restricted to English language and human studies. Thirty-two studies were included, with total populations of 3,987. The overall pooled analysis was performed by bivariate random effect model, which revealed significantly higher sensitivity and specificity of 77.1% (95% confidence interval, 76.8-78.5%) and 80.1% (95% confidence interval, 78.2-81.9%), respectively; positive likelihood ratio (3.67), negative likelihood ratio (0.26); and diagnostic odd ratio (16.24). Additionally, the area under curve exhibited significant diagnostic accuracy of 0.871. However, notable heterogeneity existed in between studies (I2=87.1%), therefore, further subgroup analysis was performed. It demonstrated ultrasonography, elastography, biomarker, and computed tomography scan had a significant overall summary sensitivity (specificity) of 89.6% (78.9%), 81.7% (83.2%), 72.2% (76.8%), and 77.2% (81.2%), respectively. Moreover, the areas under curve values were significantly higher in elastography (0.906), followed by computed tomography scan (0.847), biomarker (0.825), and ultrasonography (0.803). In future, non-invasive techniques could be the future choice of investigations for screening and diagnosis of clinically significant portal hypertension in cirrhosis. However, standardization of diagnostic indices and their cut-off values in each non-invasive method needs to be addressed.

University Teacher’s Knowledge, Personality and Teaching Effect: A Qualitative Study from Students’ Cognition Perspective

Teaching effect is a core index for measuring the validity of teaching practices in universities. How to improve it in class? It is an important issue in educational reform. From students’ cognition perspective, the study analyzed students’ statements about the knowledge, personalities and behaviour of their teachers. Through the process of text analysis, the study summarized the common elements of teachers’ knowledge and personality as well as their impacts on teaching effects. A new theory, i.e. Intellectual Management for University Teacher (IMUT), was constructed. Results show that: At first, university students can definitely cognize and appraise their teachers’ knowledge and personalities; Second, an effective combination of knowledge and personality decides one teacher’s teaching effect, and; Finally, according to the feedback of students, the elements of teacher’s knowledge should include knowledge level and knowledge behaviour, and the elements of teacher’s personality could be summarized as personality trait and personalized behaviour. In order to improve teaching effects, university teachers are suggested to implement intellectual management, for realizing intellectual beauty through building a syncretic system which helps to develop knowledge and personality together.

Relative effects of breastfeeding intention and practice on maternal responsiveness.

ABSTRACTOur objective was to examine the differential effects of antenatal breastfeeding intention (BI) and breastfeeding practice (BP) on maternal postnatal responsiveness. We conducted a secondary analysis of longitudinal data from a subsample of 962 mother–infant dyads from a U.K.‐based birth cohort study the Avon Longitudinal Study of Parents and Children. Exposures were BI and BPs measured at 32 weeks of gestation and 18 months’ postpartum. The outcome was maternal responsiveness assessed at 12 months’ postpartum. We used logistic regression analyses unadjusted and adjusted for confounders. Intention to breastfeed was associated with increased odds of postnatal maternal responsiveness independent of BP, adjusted odds ratio (OR) = 2.34, 95% CI [1.42, 3.86]. There was no evidence that BP was an independent predictor of maternal responsiveness, OR = 0.93, 95% CI [0.55, 1.57]. Life‐course epidemiology analyses demonstrated that maternal responsiveness is most positive when both BI and BP are present. This is the first population‐based study to provide evidence that BI during pregnancy is more strongly associated with maternal postnatal responsiveness than is BP. Further research is needed to understand the determinants of BI in pregnancy and its relationships with maternal responsiveness.

Analytical evaluation of coupling coefficients of a nine-core homogeneous optical fiber

Coupling coefficients due to inter-core coupling in a 9-core homogeneous multi-core optical fiber (MCF) are evaluated analytically. Variation of coupling coefficients with respect to the fiber parameters, like, core-to-core separation (pitch), core radius and relative refractive index difference are investigated. Results show that the coupling coefficients are inversely related to the core pitch and index contrast, but it increases with the increase of core radius. It is also observed that while keeping the pitch and index contrast unchanged, the core radius plays a significant role to control the coupling among the cores. Variation of coupling coefficients with relative index difference are compared with similar results reported earlier.

226. The high vs limited screw density group in posterior fusions for adolescent idiopathic scoliosis: use of the Spine Tango registry to supplement the evidence from randomized control trials

BACKGROUND CONTEXT Several randomized controlled trials (RCTs) have compared patient outcomes of The high screw density group(HSD) with those of limited screw density group(LSD). Because RCTs have known limitations with regard to their external validity, the comparative effectiveness of the two therapies in everyday practice remains unknown. PURPOSE This study was designed to compare patient-reported outcomes after HSD vs LSD based on data from an international spine registry. STUDY DESIGN/SETTING A retrospective analysis of registry data was performed. PATIENT SAMPLE Inclusion criteria were adolescent idiopathic scoliosis HSD or LSD, no previous surgery, and a Core Outcome Measures Index (COMI) completed at baseline and at least 3 months' follow-up. Overall, 877 patients were identified. OUTCOME MEASURES Construct characteristics and radiographic measurements were compared preoperatively and at last follow-up. Operative time and estimated costs were also evaluated. COMI score improvement were the outcome measures. METHODS Three separate analyses were performed to compare HSD and LSD surgical outcomes: (1) mimicking an RCT setting, with admission criteria typical of those in published RCTs, a 1:1 matched analysis was carried out in 797 patients; (2) an analysis was performed on 371 patients outside the classic RCT spectrum, that is, with one or more typical RCT exclusion criteria; (3) a subgroup analysis of all patients with additional follow-up longer than 2 years (n=279). RESULTS Matching resulted in 217 pairs with an average follow-up of 20 months that had no significant residual differences for any patient characteristics. Small but statistically significant differences in outcome were found in favor of HSD, which are potentially clinically relevant. Subgroup analyses of typical patients and of patients with longer-term follow-up showed no significant differences in outcome between the treatments. CONCLUSIONS The results of this observational study were in accordance with those of the published RCTs. Excellent curve correction, stability, and balance can be achieved using fewer screws than commonly used in posterior pedicle screw fusions for AIS. Operative time is reduced, and risk and cost are decreased with the use of limited screw density constructs.. Analysis of typical patients suggested that, in patients outside the spectrum of clinical trials, both surgical interventions appeared to work to a similar extent to that shown for the cohort in the matched study. Also, in the longer-term perspective, both therapies resulted in comparable benefits to the patients. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Several randomized controlled trials (RCTs) have compared patient outcomes of The high screw density group(HSD) with those of limited screw density group(LSD). Because RCTs have known limitations with regard to their external validity, the comparative effectiveness of the two therapies in everyday practice remains unknown. This study was designed to compare patient-reported outcomes after HSD vs LSD based on data from an international spine registry. A retrospective analysis of registry data was performed. Inclusion criteria were adolescent idiopathic scoliosis HSD or LSD, no previous surgery, and a Core Outcome Measures Index (COMI) completed at baseline and at least 3 months' follow-up. Overall, 877 patients were identified. Construct characteristics and radiographic measurements were compared preoperatively and at last follow-up. Operative time and estimated costs were also evaluated. COMI score improvement were the outcome measures. Three separate analyses were performed to compare HSD and LSD surgical outcomes: (1) mimicking an RCT setting, with admission criteria typical of those in published RCTs, a 1:1 matched analysis was carried out in 797 patients; (2) an analysis was performed on 371 patients outside the classic RCT spectrum, that is, with one or more typical RCT exclusion criteria; (3) a subgroup analysis of all patients with additional follow-up longer than 2 years (n=279). Matching resulted in 217 pairs with an average follow-up of 20 months that had no significant residual differences for any patient characteristics. Small but statistically significant differences in outcome were found in favor of HSD, which are potentially clinically relevant. Subgroup analyses of typical patients and of patients with longer-term follow-up showed no significant differences in outcome between the treatments. The results of this observational study were in accordance with those of the published RCTs. Excellent curve correction, stability, and balance can be achieved using fewer screws than commonly used in posterior pedicle screw fusions for AIS. Operative time is reduced, and risk and cost are decreased with the use of limited screw density constructs.. Analysis of typical patients suggested that, in patients outside the spectrum of clinical trials, both surgical interventions appeared to work to a similar extent to that shown for the cohort in the matched study. Also, in the longer-term perspective, both therapies resulted in comparable benefits to the patients.

A Mattress System of Recognizing Sleep Postures Based on BCG Signal

Sleep posture recognition is the core index of diagnosis and treatment of positional sleep apnea syndrome. In order to detect body postures noninvasively, we developed a portable approach for sleep posture recognition using BCG signals with their morphological difference. A type of piezo-electric polymer film sensor was applied to the mattress to acquire BCG, the discrete wavelet transform with cubic B-spline was used to extract characteristic parameters and a naive Bayes learning phase was adapted to predict body postures. Eleven healthy subjects participated in the sleep simulation experiments. The results indicate that the mean error obtained from heart rates was 0.04±1.3 beats/min (±1.96 SD). The final recognition accuracy of four basic sleep postures exceeded 97%, and the average value was 97.9%. This measuring system is comfortable and accurate, which can be streamlined for daily sleep monitoring application.

Editorial introductions

Editorial introductions