Anti-noise UWFBG-array enhanced DAS system using double-pulse-based time-domain adaptive delay interference: publisher's note.

This publisher's note contains a correction to Opt. Lett.48, 1814 (2023)10.1364/OL.486149.

Gender differences in suicidal ideation, suicide attempts, and suicide death among people living with HIV: A systematic review and meta-analysis.

OBJECTIVE: Although excess mortality, especially suicide, is a critical trait in people living with HIV, consensus about gender differences in these areas is lacking. We conducted meta-analyses to examine gender differences in suicidal ideation, suicide attempts, and suicide death among people living with HIV. METHODS: We systematically searched PubMed and Web of Science for studies written in English. In this review, suicide among people living with HIV includes suicide death, suicidal ideation, and suicide attempts. Studies reporting the suicide prevalence among males and females living with HIV were eligible for inclusion in our review. Odds ratios (ORs) and 95% confidence intervals (CIs) served as the effect size index. Fixed-effects or random-effects meta-analyses were chosen based on the size of the heterogeneity. RESULTS: A total of 27 studies comprising 801 017 participants from 11 countries were included in the meta-analysis. The overall prevalence of suicidal ideation was 18.0% (95% CI 13.3%-22.8%) in males and 20.8% (95% CI 16.4%-25.1%) in females, and there was a statistically significant higher risk of suicidal ideation in females living with HIV (OR 1.30; 95% CI 1.09-1.56; p < 0.05). The overall prevalence of suicide attempts was 16.8% (95% CI 9.0%-24.5%) in males and 24.7% (95% CI 12.4%-37.1%) in females, and there was a statistically significant higher risk of suicide attempts in females living with HIV (OR 1.34; 95% CI 1.02-1.75; p < 0.05). The pooled prevalence of suicide death was 1.2% (95% CI 0.5%-1.9%) among males and 0.2% (95% CI 0.1%-0.3%) among females, and the risk of suicide death between genders was not statistically significant (OR 0.78; 95% CI 0.50-1.24; p = 0.298). CONCLUSIONS: There were gender differences in suicidal ideation and suicide attempts among people living with HIV. Females living with HIV were more likely to experience suicidal ideation and make suicide attempts, but there were no statistically significant gender differences in suicide death. Appropriate initiatives to optimize the recognition, treatment, and management suicide behaviours of males and females living with HIV may narrow this gender gap.

Variational mode decomposition-based abnormal wheel-rail relationship detection in distributed acoustic sensing.

The distributed acoustic sensing system can obtain the vibration signal caused by the vibration of the train. By analyzing these wheel-rail vibration signals, an abnormal wheel-rail relationship identification scheme is proposed. The variational mode decomposition is employed for signal decomposition, thereby obtaining intrinsic mode functions with prominent abnormal fluctuations. The kurtosis value of each intrinsic mode function is calculated, which is compared with the threshold value for the identification of trains with abnormal wheel-rail relationship. And the extreme point of the abnormal intrinsic mode function is used to locate the bogie with an abnormal wheel-rail relationship. Experimental demonstration verifies that the proposed scheme can identify the train and locate the bogie with an abnormal wheel-rail relationship.

Anti-noise UWFBG-array enhanced DAS system using double-pulse-based time-domain adaptive delay interference.

An anti-noise interrogation technique for ultra-weak fiber Bragg grating (UWFBG)-based distributed acoustic sensing (DAS) systems is proposed and demonstrated using double-pulse-based time-domain adaptive delay interference. This technique breaks the limitation that the optical path difference (OPD) between the two arms of the interferometer should be completely matched with the entire OPD between the adjacent gratings in the traditional single-pulse system. The length of the delay fiber in the interferometer can be reduced, and the double-pulse interval can adapt flexibly to the UWFBG array with different grating spacing. The acoustic signal is restored accurately when the grating spacing is 15 m or 20 m by the time-domain adjustable delay interference. Moreover, the noise induced by the interferometer can be suppressed significantly as compared to using a single pulse, and above 8-dB signal-to-noise ratio (SNR) enhancement can be obtained without any extra optical devices when the noise frequency and the vibration acceleration are below 100 Hz and 0.1 m/s2, respectively.

Suicide rates among people with serious mental illness: a systematic review and meta-analysis.

BACKGROUND: People with serious mental illness are at great risk of suicide, but little is known about the suicide rates among this population. We aimed to quantify the suicide rates among people with serious mental illness (bipolar disorder, major depression, or schizophrenia). METHODS: PubMed and Web of Science were searched to identify studies published from 1 January 1975 to 10 December 2020. We assessed English-language studies for the suicide rates among people with serious mental illness. Random-effects meta-analysis was used. Changes in follow-up time and the suicide rates were presented by a locally weighted scatter-plot smoothing (LOESS) curve. Suicide rate ratio was estimated for assessments of difference in suicide rate by sex. RESULTS: Of 5014 identified studies, 41 were included in this analysis. The pooled suicide rate was 312.8 per 100 000 person-years (95% CI 230.3-406.8). Europe was reported to have the highest pooled suicide rate of 335.2 per 100 000 person-years (95% CI 261.5-417.6). Major depression had the highest suicide rate of 534.3 per 100 000 person-years (95% CI 30.4-1448.7). There is a downward trend in suicide rate estimates over follow-up time. Excess risk of suicide in males was found [1.90 (95% CI 1.60-2.25)]. The most common suicide method was poisoning [21.9 per 100 000 person-years (95% CI 3.7-50.4)]. CONCLUSIONS: The suicide rates among people with serious mental illness were high, highlighting the requirements for increasing psychological assessment and monitoring. Further study should focus on region and age differences in suicide among this population.

Development and validation of a Cancer Patient Suicidal Ideation Scale.

Aim: To develop a Cancer Patient Suicidal Ideation Scale (CAPASIS) and test its reliability and validity. Patients & methods: An initial CAPASIS was developed. Clinical assessment was conducted using an adjusted initial scale with 239 cancer patients for item reduction and 253 for scale validation. Results: Item selection analyses resulted in 22 items. The revised model fits were acceptable (normal chi-square [χ2/df] = 1.919; standardized root mean residual  = 0.057; root mean square error of approximation = 0.060; goodness fit index = 0.882; adjusted goodness fit index [AGFI] = 0.844; Tucker-Lewis index = 0.898; comparative fit index  = 0.915; incremental fit index  = 0.917). The Cronbach's alpha coefficient was 0.911. Conclusion: The CAPASIS has good validity and reliability, with a six-factor structure of 'entrapment', 'defeat', 'isolation', 'hopelessness', 'burdensomeness' and 'humiliation', which can help identify patients with suicidal ideation.

Effect of matrix metalloproteinases on the healing of diabetic foot ulcer: A systematic review.

BACKGROUND: This study aims to discuss the expression of matrix metalloproteinase in wound healing of diabetic foot ulcers and further summarize the strategies of targeted matrix metalloproteinase and its inhibitors in the treatment of diabetic foot ulcers. METHODS: Following PRISMA-SCR guidelines, databases (PubMed, Home-PMC-NCBI, CINAHL, Web of Science) were systematically searched from inception to 19 June 2022. Newcastle-Ottawa Scale (NOS) was used to evaluate the bias risk of the included studies. RESULTS: Eight studies are finally eligible for our systematic review. The combined data analysis of 8 studies showed that there were no significant difference in age(p = 0.110), duration of diabetes(p = 0.197), glycosylated hemoglobin content(p = 0.489), size(p = 0.133) and depth(p＞0.05) of initial ulcer between the ulcer wound healing group and the non-healing group. MMP-1, 2, 8, 9, and TIMP-1, 2 affected the healing of DFUs. In the DFUs healing group, the concentrations of MMP (MMP-1, 2, 8, 9) decreased, and the concentration of TIMP-1 increased. CONCLUSION: Our study showed that high levels of MMP-1, 2, 9 delayed the healing of diabetic foot ulcers, and high expression of MMP-8 in tissues improved wound healing. This study also summarized the effective intervention strategies for the treatment of diabetic foot ulcers.

Polarization fading suppression in distributed interferometric sensing by matched interference between polarization-switched pulses.

A polarization fading suppression technique is proposed for distributed interferometric sensing systems, based on matched interference between polarization switched pulses. For each individual sensor, two sets of interferometric outputs are obtained, one corresponding to the interference between two pulses with initially parallel polarization, the other corresponding to that between two pulses with initially orthogonal polarizations. As such, at least one output presents visibility no less than 2/2. By selecting the one with higher visibility for demodulation, the influence of polarization fading can be suppressed significantly, leading to distributed acoustic sensing with notably improved robustness and reliability.

COVID-19 in patients with systemic lupus erythematosus: A systematic review.

The objectives of the study were to review the articles to identify (a) the epidemiology of systemic lupus erythematosus (SLE) and coronavirus disease 2019 (COVID-19); (b) the clinical characteristics of SLE patients with COVID-19; (c) the treatment of COVID-19 in SLE patients; and (d) the impact of COVID-19 pandemic on SLE patients. PubMed was systematically reviewed for literature published from December 2019 to June 2021. Our search was limited to human studies, with language restriction of English. Studies were included if they reported COVID-19 in SLE patients. Our systematic review included 52 studies. The prevalence of COVID-19 infection ranged from 0.0% to 18.1% in SLE patients, and the hospitalisation rates ranged from 0.24% to 10.6%. COVID-19 infection is likely to mimic SLE flare. Hydroxychloroquine (HCQ) was ineffective in prevention of COVID-19, and SLE patients with COVID-19 faced difficulty in healthcare access, had financial constraints and suffered from psychological distress during the pandemic. The pandemic had a significant effect on mental and physical health. Adequate healthcare access, along with containment policies, social distancing measures and psychological nursing was required.

C-reactive protein and diabetic foot ulcer infections: A meta-analysis.

BACKGROUND: Accurate identification of diabetic foot ulcer infection (IDFU) through inflammatory markers is still a challenge in clinical practice. OBJECTIVES: This meta-analysis aims to investigates whether there is a significant indigenous association between CRP level and diabetic foot ulcer infection. METHODS: The studies on the diagnosis of IDFU by inflammatory marker C-reactive protein published before November 2021 in PubMed, Web of Science, Embase, and Cochrane Library were searched. Since the included seven studies were cohort studies and cross-sectional studies, the quality evaluation was founded on the standard of Newcastle-Ottawa Scale (NOS), which was convenient and straightforward. The stata 15.0 software (Cambridge, UK) was used for statistical analysis of data collected for analysis. RESULTS: Finally, we included seven articles and investigated 592 patients, including 362 patients with IDFU and 230 patients without diabetic foot ulcer infection (NIDFU). Seven studies assessed the results of CRP, with significant heterogeneity among included studies (χ2 = 18.93, P = 0.004; I2 = 68.3%). Therefore, the combined effect adopts the random effect model, and the combined impact of standardized mean difference is 0.81 (95% CI 0.49-1.12; z = 4.99, p = 0.000). The funnel plot showed no significant asymmetry, and Egger's Test (z = 0.30, P = 0.764) and Begg's Test (t = -0.50, p = 0.637) showed no publication bias. Sensitivity analysis shows that the results are robust. Through subgroup analysis, we find that regional and CRP types are both sources of high heterogeneity. Meanwhile, the meta-regression results of the random effect model showed that HbA1c (P = 0.021), BMI (P = 0.029), and creatinine levels (P = 0.003) had significant effects on the heterogeneity of the relationship between IDFU, and serum CRP levels. DISCUSSION: Meta-analysis showed a clear association between C-reactive protein and IDFU. Understanding the pathophysiology of IDFU and rapid identification of risk factors for reducing patient burdens, amputation, and mortality are essential.

Vital signs monitoring using the macrobending small-core fiber sensor.

Respiration and heartbeat monitoring during sleep is essential in the assessment of personal health. However, conventional monitoring systems are complex, expensive, and uncomfortable. In this Letter, a mat embedded with a macrobending optical fiber sensor is proposed for non-contact vital signs monitoring during sleep based on vibration sensing. Exploiting the whispering gallery mode, a small-core fiber is adopted and pre-bent to enhance sensitivity to subtle vibrations. The mat sensing system can simultaneously detect and track respiration and ballistocardiography. With high vibration sensitivity, high reliability, and good stability, the mat provides a non-contact and low-cost alternative for long-term monitoring of vital signs, especially for daily home use.

High dynamic range distributed acoustic sensing based on dual-wavelength fiber Bragg grating pairs.

A high dynamic range distributed acoustic sensing (DAS) system is demonstrated based on a dual-wavelength (2λ) interferometric acoustic sensor array, constructed using 2λ fiber Bragg grating pairs (FBGPs). Each FBGP is composed of two weak FBGs presenting -30-dB reflectivity and center wavelengths of 1535 nm and 1565 nm. With the phase demodulation results from the two wavelengths, 2λ linear regression phase unwrapping is implemented, which significantly enhances the dynamic range of the DAS system. By examining the four time-division-multiplexed sensors, an average background noise level of -105.2dBrad/Hz at 1 kHz and a cross talk level lower than -70dB at 1 kHz are achieved.

Association between social support and suicidal ideation in patients with cancer: A systematic review and meta-analysis.

OBJECTIVE: To quantitatively examine the relationship between social support and suicidal ideation (SI) among patients with cancer and identify the moderators that influence the magnitude of this association. METHODS: Publications were searched in PubMed, PsycINFO, EMBASE, Cochrane Library and Chinese National Knowledge Infrastructure from database inception to May, 2020. Correlation coefficients (r) were chosen as the effect size with a random model to evaluate the overall effect size between social support and SI in patients with cancer. To assess statistical heterogeneity, we examined potential moderator variables on the social support and SI. RESULTS: A total of 881 studies were identified in initial search, and twelve studies were eligible. A negative, small but significant correlation (r = -0.22, 95% CIs: -0.30,-0.14, p < 0.001) was observed between social support and SI in patients with cancer, with a significant heterogeneity (I2  = 95.24%, Q = 231.27, p < 0.001). Moderator analyses indicated that race/ethnicity (Q(1) = 8.4, p < 0.05) and measurements of social support (Q(3) = 9.78, p < 0.05) and SI (Q(3) = 9.69, p < 0.05) significantly moderate the effect size between social support and SI. CONCLUSION: Taken together, we found a negative yet significant association between social support and SI in patients with cancer, which supported the importance of social support for the prevention of SI in patients with cancer.

Wear measurement based on the length variation of a sacrificial FBG.

A high-precision wear measurement method with temperature stability achieved by measuring the length variation of a fiber Bragg grating (FBG) is proposed. The adoption of the optical frequency-domain reflectometry (OFDR) technology makes the spatial resolution of this measurement method reach 15.13 µm, and the offline and online measurement accuracies are 30 µm and 100 µm, respectively. The systematic error of the FBG length measuring system is within 30 µm. Because the length measurement is done with a short FBG instead of a much longer fiber, the measurement error induced by the time-varying temperature or strain is significantly reduced in the proposed method. The spatial resolution and accuracy of this method is suitable for wear measurements of various parts in the mechanical field, such as bearings, gears, and pistons.

Surface intrusion event identification for subway tunnels using ultra-weak FBG array based fiber sensing.

A scheme is proposed for the identification of surface intrusion events, from signals detected by an ultra-weak fiber Bragg grating array in a subway tunnel. The spectral subtraction and the root mean square of the power spectral density are combined to extract event signals. The local characteristics-scale decomposition and the multi-scale permutation entropy are employed subsequently for feature extraction, which can improve the event recognition rate from the perspective of multi-scale analysis. Experimental demonstration verifies that the proposed scheme can identify four common events. Among the events, the discrete pulse construction and the continuous pulse construction on the ground surface are intrusion events, the subway train traveling in the tunnel and the lorry passing on the ground surface are non-intrusion events. The average recognition rate of 96.57% is achieved, which can satisfy actual application requirements.

High-sensing-resolution distributed hot spot detection system implemented by a relaxed pulsewidth.

Reliable sensing and accurate location of a weak and small hot spot are critical for applications in industrial infrastructure monitoring. We propose and experimentally demonstrate a practical and reliable distributed hot spot detection method using ultra-weak fiber Bragg gratings (UWFBGs) array and optical time-domain reflectometry (OTDR) based interrogator. To reliably detect the hot spots, the grating spacing of the sensor array is decreased to a similar size of the hot spot. All UWFBGs within a fiber section (FS) are considered as one sensing element, and the wavelength-division multiplexing technique is introduced to reduce crosstalk between adjacent FSs. To retrieve the sensing information, the proposed FS spectrum interrogation method based on OTDR technology is numerically analyzed and experimentally demonstrated. The interrogator exploits the reflection spectrum of each FS instead of each grating, enabling the low-speed hardware implementation of the whole demodulation method. Experimental results show that the expected hot spot can be successfully detected with a sensing resolution of 10 cm and a location resolution of 1 m over a range of 2 km by exploiting 10-ns pulsewidth. Besides, the temperature measurement can be demonstrated with a temperature sensing precision of ± 1°C and a measurement time of 1.5 s, which are meaningful for the early warning of centimeters-sized fire source in some oil and gas pipelines monitoring applications.

Multipoint acoustic impedance sensing based on frequency-division multiplexed forward stimulated Brillouin scattering.

Acoustic impedance sensing based on forward stimulated Brillouin scattering (FSBS) in fiber has attracted the attention of researchers in recent years. Here, we propose a novel, to the best of our knowledge, multipoint sensing scheme based on FSBS, which explores frequency-division multiplexing. Since the resonance center frequencies of the FSBS-invoked acoustic modes are dependent on the fiber diameter, different fiber sections can be differentiated using carefully selected representative peaks in the FSBS spectrum. With a Sagnac loop structure, continuous-wave light is adopted for FSBS excitation, reducing the required fiber length for efficient opto-acoustic interaction. By evaluating the linewidths of representative peaks, simultaneous acoustic impedance sensing at multiple locations is realized with 0.8 m sensor size.

Noise resilient quasi-distributed sensing with an interferometric-noise-suppressing Golay coded optical source.

A noise-resilient demodulation technique is proposed and demonstrated with an interferometric-noise-suppressing (INS-) Golay coded optical pulse source for a quasi-distributed sensor array constructed by identical ultra-weak fiber Bragg gratings (UWFBGs).In combination with a medium coherence light source, coding-based time-efficient noise reduction is facilitated for closely-multiplexed UWFBG arrays, for which conventional Golay coding is inapplicable. With 32-bit INS-Golay coded pulse trains, 5.6-dB signal-to-noise ratio improvement is achieved as compared to the case where an uncoded pulse train is adopted. While the performance is almost as good as 32-time averaging, the time consumption for signal acquisition is only ∼1/8. The proposed INS-Golay coding method exhibits linearity up to 0.9986 in temperature sensing with a wavelength demodulation error of ∼±5 pm. The time efficiency of the method increases with increased code length, providing a solution that alleviates the trade-off between the demodulation accuracy and speed in the UWFBG-based sensing systems with closely-multiplexed sensors.

Interrogation of a large-capacity densely spaced fiber Bragg grating array using chaos-based incoherent-optical frequency domain reflectometry.

An interrogation technique for large-capacity densely spaced fiber Bragg grating (FBG) arrays is demonstrated using incoherent optical frequency domain reflectometry (I-OFDR). A distributed-feedback laser diode under chaotic oscillation, modulated by a frequency-swept microwave, is adopted as the optical source. The reflected sensing signals are converted into electrical signals and subsequently mixed with the original microwave. Fast Fourier transform is applied to the generated beat signal to obtain the position of individual FBGs, while thermal tuning of the lasing wavelength leads to the demodulation of wavelength. By using the chaotic source, interference among the reflected sensing signals is reduced, leading to a significantly improved spatial resolution of 10 cm, with a multiplexing capacity of 3640 and wavelength demodulation accuracy of 15 pm.

Global recurrence rates in diabetic foot ulcers: A systematic review and meta-analysis.

Recurrence rates of diabetic foot ulcers vary widely in the published literature. The aim of this systematic review is to estimate recurrence rates of diabetic foot ulcers. We did a PubMed search and performed a review of reference lists for studies reporting recurrence of diabetic foot ulcers. The weighted relative risk (RR) and corresponding 95% confidence interval (CI) for recurrence was estimated. Forty-nine studies reporting recurrence of diabetic foot ulcers were included. A pooled estimate for recurrence rate was 22.1% per person-year (py) (95% CI, 19.0-25.2%). Recurrence rate was 24.9% per py in Europe (95% CI, 20.0%-29.7%), 17.8% per py in North America (95% CI, 12.7%-22.9%), 16.9% per py in Africa (95% CI, 4.7%-29.0%), and 17.0% per py in Asia (95% CI, 11.1%-23.0%). Turkey had the highest recurrence rate of 44.4% per py (95% CI, 24.9%-63.9%), and Bangladesh had the lowest of 4.3% per py (95% CI, 2.3%-6.3%). Recurrence rates of diabetic foot ulcers before 2002, between 2002 and 2008, and after 2008 were 22.2% per py (95% CI, 17.6%-26.8%), 21.9% per py (95% CI, 17.0%-26.8%), and 21.8% per py (95% CI, 16.3%-27.2%), respectively. Recurrence rates of diabetic foot ulcers are high. Recurrence rates vary widely in different regions and have decreased recently. More attention towards recurrence of diabetic foot ulcers is urgently required.