Construction of a postoperative infection outbreak investigation form: A tool for early detection and control measures.

BACKGROUND: To develop an investigation form for postoperative infection outbreak (PIO), and to identify sources of the outbreak in the early stage. METHODS: After an exhaustive literature review, we used the Delphi method to determine the indicators and relative risk scores of the assessment tools through 2 rounds of specialist consultation and overall consideration of the opinions and suggestions of 20 specialists. RESULTS: A total of 203 studies of PIO were eligible for inclusion. The mean authority coefficient (Cr) was 0.87. Kendall's W coefficient of the specialist consultation was 0.704 after 2 rounds of consultation (P < .005), suggesting that the specialists had similar opinions. Based on 4 primary items and 19 secondary items of the source of PIO, and tripartite distribution characteristics of infected patients, we constructed the PIO investigation form. CONCLUSIONS: The PIO investigation form can be used in the investigation of the early-stage cluster of cases, it's a prerequisite for taking effective control measures, avoiding PIO occurrence. However, the effect of the investigation form needs to be further evaluated.

Tens of hertz ultra-narrow linewidth fiber ring laser based on external weak distributed feedback.

We suggest and demonstrate a single-frequency fiber ring laser with an ultra-narrow linewidth based on an external weak distributed feedback. A π phase-shifted fiber Bragg grating (PSFBG) is used to improve mode selection and enable single-longitudinal mode (SLM) laser operation. The linewidth is then further strongly compressed using a signal generated by a weak distributed feedback structure (WDFS) and injected into the main laser cavity to suppress spontaneous emission. The resulting ultra-narrow linewidth fiber ring laser achieves a side-mode suppression ratio (SMSR) of ∼72 dB, and low white frequency noise of ∼10.3 Hz2/Hz, which correspond to an instantaneous linewidth of ∼32.3 Hz in the normal operating condition of the laser. Our linewidth compression mechanism not only solves the problems associated with deep linewidth compression in long-cavity fiber laser, but also fosters the development of practical and reliable all-fiber structures. Our laser source is characterized by low cost, high coherence, and low noise, which are highly desirable features in coherent optical detection, high-resolution spectrometers, microwave photonics, and optical sensing.

Dynamic phase retrieval method for ultrafast and precise vibration sensing based on time stretching.

We demonstrate a method for retrieving the phase information from single-shot interference spectra obtained by dispersive Fourier transform, through which the error accumulation during phase retrieval is restrained. A Mach-Zehnder interferometer is proposed for vibration sensing with high speed. We find that relative phase trends at different time delays can be precisely retrieved to improve the signal-to-noise ratio when the time interval jitter between pulses within two arms is less than four times the pulse width. The verification experiment achieves a phase resolution of 5.3 mrad and a high-speed refresh frame rate of 51.8 MHz. Numerical simulations and experiments show that the method is effective for phase demodulation of dynamic interference spectra, and provides a reliable strategy for high-speed, precision sensing.

High speed surface defects detection of mirrors based on ultrafast single-pixel imaging.

High speed surface defects detection of mirrors is of great significance, for detecting the quality of the mirrors on-site, and ultimately for monitoring the operating states of laser systems. The speeds of conventional proposals are relatively low as they utilize mechanically scanning methods or two-dimensional charge-coupled devices. Here, we propose a high speed surface detection method based on ultrafast single-pixel imaging, which consists of a spatial Fourier optical module for frequency-space mapping and a dispersive Fourier transform module for frequency-time mapping. An optical grating is utilized to map the wideband spectrum of dissipative soliton into the spatial domain under far-field diffraction, where the mirror is inspected. Dispersive Fourier transform is used to map the surface-defects-coded spectral information into the temporal domain, then recorded by a high speed single-pixel detector. The detection system permits continuous single-shot spectra measurement with a frame rate equivalent to the pulse repetition rate (8.4 MHz). We extract amplitude defects by demodulating light intensity, and obtain phase defects by demodulating the interference spectrum with a Mach-Zehnder interferometer structure. Experimental results show that the damaged mirror with a two-dimensional width of 10 × 13 mm can be obtained with a spatial resolution of 90 µm. The obtained phase accuracy after Hilbert transformation is 0.00217 rad, corresponding to a depth resolution of 51 nm. This scheme can find promising applications for surface defects detection of large aperture mirrors, and real-time monitoring of laser systems with high energy.

Comparative effectiveness and safety of antiviral agents for patients with COVID-19: Protocol for a systematic review and individual-patient data network meta-analysis.

BACKGROUND: A recent cluster of pneumonia cases in Wuhan, China, has been caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We propose the protocol described below to perform an individual-patient data (IPD) network meta-analysis (NMA) in order to evaluate the efficacies of different antiviral drugs to treat patients with coronavirus disease 2019 (COVID-19). MATERIALS AND METHODS: We will search the Medline, EMBASE, Cochrane Library, SinoMed, CNKI and VIP databases from their inceptions through July 2020. There will be no restrictions on language, publication year, or publication type. Randomized clinical trials (RCTs) and prospective cohort studies with antiviral treatments for COVID-19 will be considered. Two reviewers will independently select studies and collect data. Risk-of-bias assessments will be completed using the Cochrane risk-of-bias scale. Primary outcome will be the COVID-19 recovery rate. We will combine aggregated data from IPD with the NMA in a single model, compare the effects of different antiviral drugs on patient-relevant efficacy, and rank the results to decide which is the most effective. TRIAL REGISTRATION: PROSPERO registration number: CRD42020167038.

Indirect comparison of efficacy between different antibiotic prophylaxis against the intracranial infection after craniotomy.

BACKGROUND: Many studies had shown that prophylactic use of antibiotics could significantly reduce the intracranial infection (ICI) rate of craniotomy. However, there has been no comparison of these antibiotics. METHODS: An electronic database search was performed, from inception to June 102,020. Randomized controlled trials (RCT) using different intravenous antibiotics (IVA) against the ICIs after craniotomy were considered. The primary outcome was the incidence rates of ICIs. An indirect treatment comparison (ITC) was conducted to compare the protective effect among the diverse antibiotic prophylaxis to prevent ICIs after craniotomy. Risk of potential bias was assessed. RESULTS: A total of 3214 patients after craniotomy in 11 studies were included, 159 patients experienced postoperative ICI, including 33 patients in the antibacterial group and 126 in the control group. The calculate results of meta-analysis showed that except fusidic acid, preoperative intravenous injection of cephalosporin, clindamycin, vancomycin, and penicillin can significantly reduce the incidence of ICI after craniotomy, and ITC showed there was no statistically significance difference in the rates of post craniotomy ICI between the various antibiotics. CONCLUSION: The current evidence shows that low-grade antibacterial drugs can be selected to prevent ICI after craniotomy, but this may be due to the limited number of studies per antibiotic. It still needs more high-quality, large sample RCT to confirm. SYSTEMIC REVIEW REGISTRATION: PROSPERO CRD42019133369.

Status and Challenges of Public Health Emergency Management in China Related to COVID-19.

Objective: This study aimed at exploring the current development status and problems of health emergency management in China and provides a reference for improving, constructing, and implementing a public health emergency management system. Methods: Cases of major and severe public health emergencies in China were analyzed along with the relevant health emergency management literature from the last decade. Results: China's health emergency system gradually improved during the study period. Monitoring and early warning systems were significantly strengthened. Material reserves and transfer management systems were constantly improved. However, the operational efficiency of command and decision systems was low, versatile talent accounted for a relatively small proportion, and emergency fund investment was insufficient. Conclusion: Constructing a sound and scientific emergency management mechanism is a lengthy and challenging process. To establish an emergency management mode for public health emergencies that is appropriate for China, it is necessary to solve existing problems and learn from the models and experiences of developed foreign countries.

A fluorometric optical fiber nanoprobe for copper(II) by using AgInZnS quantum dots.

An optical fiber nanoprobe is presented for fluorometric determination of copper(II). The method based on the use of water-dispersible AgInZnS quantum dots (QDs) deposited at the end of an optical fiber in a poly(vinyl alcohol) matrix. The fluorescnece of the QDs, best measured at excitation/emisssion wavelengths of 365/570 nm, is quenched by Cu(II) due to both static and electron transfer from the QDs to Cu(II). This is experimentally confirmed by photoluminescence and UV-vis absorption spectra, and measurement of luminescence lifetimes. The probe is highly selective and possesses a linear detection range that extends from 2.5 to 800 nM. Graphical abstractSchematic representation of an optical fiber nanoprobe based on hydrophilic AgInZnS quantum dots for fluorometric determination of copper(II). The fluorescence is quenched by Cu(II) due to static quenching and dynamic quenching. It has a detection range of 2.5-800 nM.

Optical polarization rogue waves from supercontinuum generation in zero dispersion fiber pumped by dissipative soliton.

Optical rogue waves emerge in nonlinear optical systems with extremely large amplitudes, and leave without a trace. In this work, we reveal the emergence of optical polarization rogue waves in supercontinuum generation from a zero-dispersion fiber, pumped by a dissipative soliton laser. Flat spectral broadening is achieved by modulation instability, followed by cascaded four-wave-mixing. In this process, we identify the emergence of optical polarization rogue waves, based on the probability density function of the relative distance among polarization states. Experimental results show that optical polarization rogue waves originate from vector multi-wave-mixing. Besides, we observe double peaks, and even triple peaks in the histogram of the state of polarization. This is a new and intriguing property, never observed so far in optical rogue waves, for example those emerging in the statistics of pulse intensities. Our polarization domain statistical analysis provides a new insight into the still debated topic of the mechanism for rogue wave generation in optical supercontinuum.

Nitrogen doped graphene quantum dots as a fluorescent probe for mercury(II) ions.

A highly selective fluorescent probe for Hg2+ is reported. It consists of nitrogen doped graphene quantum dots (NGQDs) that are nearly spherical in shape, have an average diameter of 2.7 nm and excitation-independent emission. The blue fluorescence of the NGQDs (with maximum excitation/emission at 378/447 nm) is quenched by Hg2+ due to both dynamic and static quenching. The probe has a wide detection range (2.5 µM - 800 µM) and a limit of detection of 2.5 µM. The dynamic and static quenching constants are 417 M-1 and 63500 M-1, respectively. The probe was used to quantfy Hg2+ in spiked real water samples with satisfactory results. Graphical abstract ᅟ.

Coherent optical modulation of graphene based on coherent population oscillation.

The optical modulation of graphene circumvents the "electrical bottleneck" in electrical field tuning of the Fermi level and motivates diverse graphene-based controllable photonic devices with extraordinary performances. Unfortunately, pervious optical modulation schemes are incoherent, and the Fermi-Dirac distribution formed from a strong pump laser prevents the absorption of a weak probe laser due to the Pauli blocking, making the modulation inconvenient and low in efficiency. Here we demonstrate the coherent optical modulation of graphene based on coherent population oscillation, where ground state population oscillates with a beat frequency equal to the pump and probe frequency difference. To distinguish it from the coexisting incoherent modulation in graphene, a phase-sensitive pump-probe system is constructed with a fiber-based Mach-Zehnder interferometer. Clear resonance within the burning hole of a pump laser is observed in the interference spectrum of a coherent probe laser. The discovery of highly coherent ground state population oscillation in graphene offers new possibilities for manipulating and controlling the phase response of graphene-based photonics with high efficiency.

Optically controlled tunable ultra-narrow linewidth fiber laser with Rayleigh backscattering and saturable absorption ring.

We propose an optically controlled tunable ultra-narrow linewidth fiber laser assisted with the mode selection induced by a saturable absorption interference ring and linewidth narrowing of fiber Rayleigh backscattering (RBS). The interference ring serves as an artificial narrow-band filter, which conduces to the laser operating at a single-frequency state. To realize narrower linewidths, additional single-mode fiber is utilized to accumulate a weak RBS feedback. On basis of inherent wavelength universality of this linewidth-narrowing mechanism, an all-optical technique is employed to enable linear and stable tunability of the laser. Cooperating with a micro-fiber Bragg grating covered by graphene, the lasing wavelength is tuned precisely and reversibly with a sensitivity of 12.4 pm/mW and a linear fitting R2 over 0.997 by changing the power of a controlling beam. During a stability test with the controlling pump power fixed, the long-term free-running power fluctuation is less than 0.5%. The Output laser linewidth is compressed to be ~200 Hz, which is also confirmed by the descending frequency noise spectrum.

Graphene-based all-optical multi-parameter regulations for an ultrafast fiber laser.

Ultrafast lasers with tunable capabilities of pulse duration and spectrum have widespread applications in telecommunication, spectroscopy, and nonlinear optical bio-imaging. However, traditional mechanical and electrical tuning methods are still challenging for precise and stable controlling. Based on graphene's photo-thermal effect, we tune the bandwidths and wavelengths of chirped fiber Bragg gratings with flexible graphene-coating approaches. By inserting the fabricated devices into an ultrafast fiber laser cavity, durations and wavelengths of the generated pulses can be all-optically tuned with sensitivities of 470 fs/mW and 2.9 pm/mW, separately. Such an optical-controlled method provides a compact and precise way to regulate various laser properties.

Comparison of the preventive effect of urethral cleaning versus disinfection for catheter-associated urinary tract infections in adults: A network meta-analysis.

BACKGROUND: Catheter-associated urinary tract infections (CAUTIs) are the main cause of infectious complications in patients with indwelling urinary catheters (IDCs). However, the best cleaning methods for the prevention of CAUTIs have not been evaluated clearly in previous studies. METHODS: An electronic database search was performed, from inception to December 2017. Randomized controlled trials and quasi-experimental trials using different methods of urethral cleaning versus disinfection to prevent CAUTIs were considered. The study selection and data collection were performed independently by two reviewers. The risk of bias assessment was performed using the Cochrane risk of bias scale. The primary outcome was the incidence rates of CAUTIs. A network meta-analysis was conducted to compare the effect among the different methods of urethral cleaning versus disinfection to prevent CAUTIs. RESULTS: Thirty-three studies (6490 patients) with seven different methods of urethral cleaning versus disinfection were eligible for inclusion, and the data were summarized in the network meta-analysis. No evidence of heterogeneity (P>0.05) was observed among the studies. The network meta-analysis showed that there was no difference in the incidence of CAUTIs when comparing the different urethral cleaning methods versus disinfection (P>0.05 for all). However, chlorhexidine ranked first in the results of the Bayesian analysis and is recommended for preventing CAUTIs. CONCLUSIONS: Current evidence suggests that there are no significant differences among different urethral cleaning versus disinfection methods with regard to CAUTI incidence rates.

Brillouin Frequency Shift of Fiber Distributed Sensors Extracted from Noisy Signals by Quadratic Fitting.

It is a basic task in Brillouin distributed fiber sensors to extract the peak frequency of the scattering spectrum, since the peak frequency shift gives information on the fiber temperature and strain changes. Because of high-level noise, quadratic fitting is often used in the data processing. Formulas of the dependence of the minimum detectable Brillouin frequency shift (BFS) on the signal-to-noise ratio (SNR) and frequency step have been presented in publications, but in different expressions. A detailed deduction of new formulas of BFS variance and its average is given in this paper, showing especially their dependences on the data range used in fitting, including its length and its center respective to the real spectral peak. The theoretical analyses are experimentally verified. It is shown that the center of the data range has a direct impact on the accuracy of the extracted BFS. We propose and demonstrate an iterative fitting method to mitigate such effects and improve the accuracy of BFS measurement. The different expressions of BFS variances presented in previous papers are explained and discussed.

Can money heal all wounds? Social exchange norm modulates the preference for monetary versus social compensation.

Compensation is a kind of pro-social behavior that can restore a social relationship jeopardized by interpersonal transgression. The effectiveness of a certain compensation strategy (e.g., repaying money, sharing loss, etc.) may vary as a function of the social norm/relationship. Previous studies have shown that two types of norms (or relationships), monetary/exchange and social/communal, differentially characterize people's appraisal of and response to social exchanges. In this study, we investigated how individual differences in preference for these norms affect individuals' perception of others' as well as the selection of their own reciprocal behaviors. In a two-phase experiment with interpersonal transgression, we asked the participant to perform a dot-estimation task with two partners who occasionally and unintentionally inflicted noise stimulation upon the participant (first phase). As compensation one partner gave money to the participant 80% of the time (the monetary partner) and the other bore the noise for the participant 80% of the time (the social partner). Results showed that the individuals' preference for compensation (repaying money versus bearing noise) affected their relationship (exchange versus communal) with the partners adopting different compensation strategies: participants tended to form communal relationships and felt closer to the partner whose compensation strategy matched their own preference. The participants could be differentiated into a social group, who tended to form communal relationship with the social partner, and a monetary group, who tended to form communal relationship with the monetary partner. In the second phase of the experiment, when the participants became transgressors and were asked to compensate for their transgression with money, the social group offered more compensation to the social partners than to the monetary partners, while the monetary group compensated less than the social group in general and showed no difference in their offers to the monetary and social partners. These findings demonstrate that the effectiveness of compensation varies as a function of individuals' preference for communal versus monetary norm and that monetary compensation alone does not heal all wounds.