Identifying Interpretable Latent Factors with Sparse Component Analysis.

In many neural populations, the computationally relevant signals are posited to be a set of 'latent factors' - signals shared across many individual neurons. Understanding the relationship between neural activity and behavior requires the identification of factors that reflect distinct computational roles. Methods for identifying such factors typically require supervision, which can be suboptimal if one is unsure how (or whether) factors can be grouped into distinct, meaningful sets. Here, we introduce Sparse Component Analysis (SCA), an unsupervised method that identifies interpretable latent factors. SCA seeks factors that are sparse in time and occupy orthogonal dimensions. With these simple constraints, SCA facilitates surprisingly clear parcellations of neural activity across a range of behaviors. We applied SCA to motor cortex activity from reaching and cycling monkeys, single-trial imaging data from C. elegans, and activity from a multitask artificial network. SCA consistently identified sets of factors that were useful in describing network computations.

Assessment of residual dizziness after successful canalith repositioning maneuvre in benign paroxysmal positional vertigo patients: a questionnaire-based study.

OBJECTIVE: The purpose of this study was to assess residual dizziness (RD) after successful canalith repositioning maneuvre (CRM) treatment in patients with benign paroxysmal positional vertigo (BPPV) using Dizziness Handicap Inventory (DHI) questionnaire and Visual Analog Scale (VAS). METHODS: One hundred sixty BPPV patients after successful CRM treatment were recruited. All patients were divided into the residual dizziness (RD) group and without RD group. The DHI questionnaire and VAS before CRM and follow-up were asked to complete. For analysis of the improvement in symptom, we defined ∆DHI and ∆VAS as the difference between the baseline score and the follow-up score. RESULTS: High incidence of RD was observed in the older patients (p < 0.001). The incidence of hypertension in the RD group was also significantly higher than that of the without RD group (p = 0.022). The ∆DHI-P, ∆DHI-E, ∆DHI-F, ∆DHI-T, and ∆VAS scores in the without RD group were significantly higher than that of the RD group (p < 0.001). When the cutoff point of the ∆DHI total scores was 17, the sensitivity was 64.86% and the specificity was 73.26% for diagnosing RD. When the cutoff point of the ∆VAS scores was 2.5, the sensitivity was 77.03% and the specificity was 81.40% for diagnosing RD. CONCLUSIONS: RD is prone to occur in the older patients and ∆VAS exhibits higher sensitivity and specificity in assessing RD.

Risk Factors of Residual Dizziness After Successful Treatment for Benign Paroxysmal Positional Vertigo in Middle-Aged and Older Adults.

Objective: The purpose of this study was to analyze risk factors of residual dizziness (RD) after successful treatment for benign paroxysmal positional vertigo (BPPV) in middle-aged and older adults. Methods: 181 patients with BPPV, after successful canalith repositioning maneuver (CRM) treatment, were recruited. All patients were divided into the middle-aged group (aged 45-59 years, n = 101) and the older group (over 60 years, n = 80). The clinical characteristics were recorded, including age, gender, numbers of maneuvers, involved canal, affected side, RD, comorbidities, dizziness handicap inventory score, and generalized anxiety disorder's 7-item scale score. Results: The incidence of RD in the older group was significantly higher than that of the middle-aged group (p = 0.033). Multivariate logistic regression analysis shows that age (odds ratio = 1.042, p = 0.006), moderate to severe dizziness (odds ratio = 2.017, p = 0.034), and moderate to severe anxiety (odds ratio = 2.228, p = 0.017) were independently associated with RD in middle-aged and older adults. Conclusion: Older adults exhibited higher incidence of RD after successful treatment for BPPV. Age, moderate to severe dizziness, and moderate to severe anxiety were independent risk factors of RD in middle-aged and older adults.

The Association Between Precuneus Function and Residual Dizziness in Patients With Benign Paroxysmal Positional Vertigo.

Objectives: The purpose of this study was to apply the amplitude of the low-frequency fluctuation (ALFF) method to investigate the spontaneous brain activity alterations in patients with residual dizziness (RD) after successful canalith repositioning manoeuvre for benign paroxysmal positional vertigo (BPPV). Methods: All BPPV patients underwent visual vertigo analog scale (VVAS) evaluations and functional magnetic resonance imaging (fMRI). The ALFF method was used to assess the spontaneous brain activity. Screening of brain regions with significant changes in ALFF values was based on analysis of the whole brain. We further analyze the relationship between ALFF values of the altered regions and VVAS scores in BPPV patients with RD. Results: Fifteen BPPV patients with RD and fifteen without RD were recruited in this study. In contrast to without RD, RD patients exhibited increased scores in VVAS tests (p < 0.001) and RD patients also showed significant ALFF decrease in the bilateral precuneus (left: 251 voxels; x = -10, y = -69, z = 51; peak t-value = -3.25; right: 170 voxels; x = 4, y = -59, z = 42; peak t-value = -3.43). Correlation analysis revealed that the mean ALFF z-values in the left precuneus displayed significant negative correlations with the VVAS scores(r = -0.44, p = 0.01). Conclusions: This study shows that RD is associated with left precuneus function as revealed by fMRI. It might provide useful information for explaining neural mechanisms in BPPV patients with RD.

[Pollution Characteristic and Control Factor Analysis of Atmospheric Ozone During Summer Typical Periods in Linyi, Shandong].

In June 2020, an observation experiment of O3 and its precursors was carried out in Linyi City, Shandong Province. Based on the observation data and MCM photochemical model simulation, the formation mechanism and control mechanism of an ozone pollution case in mid-June were analyzed. The study found that, despite the high precipitation during the observation period, ozone concentrations rapidly accumulated and exceeded the limits once the weather cleared, with the 1-h average and 8-h φ (O3) exceeding the national ambient air quality standards on 10 days (32% in frequency)and 14 days (45%), respectively. The diurnal variation in O3 concentration was unimodal and accompanied by the afternoon peak at 16:00. MCM simulation results showed that the daily net reaction rate of O3 was 20×10-9 h-1, and HO2·+NO and RO2·(except CH3O2·)+NO contributed 49.0%-51.1% and 37.3%-40.2% of O3 generation, respectively. The contribution of the·OH+NO2 reaction to the total consumption of O3 was 35.1%-57.4%. The results of VOCs reactivity, relative incremental reactivity (RIR), and the EKMA curve method showed that the generation of O3 was more sensitive to alkenes (mainly trans-2-pentene and trans-2-butene)and aromatics (mainly m/p-xylene and toluene)but was negatively sensitive to NOx. In other words, the reduction in VOCs concentration would lead to the decrease in O3 concentration, whereas the reduction in NOx concentration would lead to the increase in O3 concentration. PMF source analysis results showed that volatile sources used by solvents and vehicle exhaust emissions contributed significantly to the above key precursor VOC species. Considering the titration effect of NO from vehicle exhaust emissions on ozone, controlling the use of volatile sources of solvents can realize the control of O3 pollution accurately and efficiently.

Research on Operation Efficiency and Membrane Fouling of A2/O-MBR in Reclaimed Water Treatment.

Taking the public building domestic wastewater as an example, the combination of the MBR (membrane bioreactor) process and the traditional A2/O (anaerobic-anoxic-oxic) process was established and analyzed in terms of the removal effect of the pollutants, the impact of the microbial community changes on the process, the MBR membrane fouling, the cleaning methods, and the cleaning performance. The results indicated that the effluent water quality of the domestic wastewater treated with the A2/O-MBR process was stable and met the emission requirement to the natural water body. There was good microbial diversity in raw water, the anaerobic tank, the anoxic tank, the aerobic MBR tank and the disinfection tank, and the aerobic MBR tank has a wide variety of aerobic microorganisms, which elevates the removal of organics and the nitrification of ammonia nitrogen and ensures the qualification of nitrogen and phosphorus indexes of the system effluent water. For the fouled membrane, the surface of the contaminated membrane was covered by macromolecular contaminants, causing the membrane flux to drop, and after different cleaning methods to the membrane were compared, it was discovered that the combined use of cleaning agents had better effects than the single ones, and the cleaning method of sodium hydroxide followed by hydrochloric acid showed the best effect, achieving a membrane flux restoration ratio above 80% after cleaning.

Simultaneous detection of 13 viruses involved in meningoencephalitis using a newly developed multiplex PCR Mag-array system.

BACKGROUND: The early detection and identification of pathogens in central nervous system viral infections associated with neurological disease increases the survival rate. However, the limitations of current diagnostic methods contribute to a lack of proper diagnosis in 62% of patients. Therefore, a robust method for detecting multiple viruses in a single reaction with high specificity, throughput, and speed is required. METHODS: A multiplex PCR Mag-Array (MPMA) system was developed that integrates three strategies: chimeric primer design, temperature switch PCR, and MagPlex-TAG techniques. The MPMA was used to amplify 13 target viral sequences simultaneously, with plasmids containing specific viral sequences as standard samples. To evaluate its clinical performance, 177 cerebrospinal fluid (CSF) samples were tested. RESULTS: The MPMA system presented high specificity and efficiency in detecting a control panel of 13 plasmids. Among 177 CSF samples, consistent results were achieved for 19 samples pre-tested using a commercial kit. Viral pathogens were found in 28/138 undiagnosed samples, with herpes simplex viruses (HSV-1 and HSV-2) being predominant. The 20 non-infectious samples revealed negative results. Compared to sequencing methods, sensitivity for detecting HSV-1 and HSV-2 was 100% and 98.78%, respectively, and specificity was 100% and 98.22%, respectively. CONCLUSIONS: A robust MPMA system that can simultaneously and reliably detect 13 meningoencephalitis-associated viruses with high specificity, throughput, and speed has been developed.