39 research outputs found

    HERMITIAN POSITIVSTELLENSATZE AND INTEGRAL OPERATORS

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    Ph.DDOCTOR OF PHILOSOPH

    Ultralow noise C + L wideband WDM-IMDD transmission at 18 × 112 Gbps by using hybrid second-order distributed Raman and first-order lumped Raman amplification

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    We experimentally investigated and demonstrated an ultralow noise hybrid amplifier that combines second-order distributed Raman amplifier (DRA) and first-order lumped Raman amplifier (LRA) in a cascaded approach. This approach allows for the reutilization of pump light from the LRA as the seed light in the second-order DRA, and simultaneous full-band dispersion compensation is realized by using dispersion compensation fiber in the LRA. This approach also supports broadband gain flattening based on the separated DRA and LRA configuration. The transmission application of the proposed amplifier was investigated using a set of 10 external cavity lasers (ECLs) in the C-band and 8 ECLs in the L-band. Ranging from 1531.12 nm to 1595.49 nm across C + L band, the proposed hybrid amplifier gives a maximum on-off gain of 27.2 dB and an average gain of 23.4 dB, with an extremely low effective noise figure (NF) of lower than -2.9 dB. Intensity modulation direct detection (IMDD) signal transmission is carried out at two different data rates across these 18 wavelengths in the C + L band: (1) 56 Gbps/λ PAM-4 signal; (2) 112 Gbps/λ PAM-4 signal. The results show that the error free transmissions are demonstrated over 101.6 km EX2000 fiber using both signals with 7% HD-FEC and 20% SD-FEC, respectively

    Relationship between occupational stress, job burnout, and depressive symptoms among workers in an automobile manufacturing enterprise in Guangzhou

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    BackgroundThe operation mode of automobile manufacturing industry (AMI) makes workers have different degrees of occupational stress and burnout, which may lead to negative emotions and depressive symptoms. ObjectiveTo study the relationship between occupational stress, job burnout, and depressive symptoms in AMI workers. MethodsIn this study, 1300 workers from a Guangzhou AMI company were selected as subjects by cluster random sampling method. Occupational stress, job burnout, and depressive symptoms of the workers were assessed by using the Effort-Reward Imbalance (ERI) questionnaire, the Maslach Burnout Inventory general survey questionnaire, and the Patient Health Questionnaire-9, respectively. Hierarchical regression was used to analyze the effects of occupational stress and job burnout on depressive symptoms in AMI workers. Mediating effect model was used to analyze the mediating effect of job burnout on the relationship between occupational stress and depressive symptoms. ResultsThere were 1300 questionnaires distributed, 1228 valid questionnaires collected, with a 94.5% recovery rate. The ERI ratio of 1228 AMI workers was 1.06±0.72, and the positive rate of occupational stress was 37.3% (458/1228). The score of job burnout was 2.18±1.37, and the positive rate of job burnout was 62.6% (769/1228). The score of depressive symptoms was 10.27±6.42, and the positive rate of depressive symptoms was 47.1% (578/1228). The dimensional scores of effort and over-commitment in occupational stress as well as emotional exhaustion and depersonalization in job burnout of AMI workers were positively correlated with the depressive symptom scores (rs=0.415, 0.571, 0.573, 0.593, P<0.05). The dimensional scores of reward and personal achievement were negatively correlated (rs=−0.454, −0.339, P<0.05). The percentages of variance in depressive symptoms score explained by occupational stress and job burnout were 26.7% and 16.6%, respectively. Job burnout had a partial mediating effect between the three dimensions of occupational stress and depressive symptoms, and the mediating effect values were −0.2832 (95%CI: −0.3250– −0.2434), 0.3553 (95%CI: 0.3071–0.4041), and 0.4193 (95%CI: 0.3681–0.4725), respectively. ConclusionAMI workers' occupational stress affects job burnout, but also indirectly affects depressive symptoms. Job burnout partially mediates the association between occupational stress and depressive symptoms. Reducing occupational stress and burnout levels of AMI workers may alleviate depressive symptoms

    Co-delivery of siRNAs and anti-cancer drugs using layered double hydroxide nanoparticles

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    In this research we employed layered double hydroxide nanoparticles (LDHs) to simultaneously deliver an anticancer drug 5-fluorouracil (5-FU) and Allstars Cell Death siRNA (CD-siRNA) for effective cancer treatment. The strategy takes advantage of the LDH anion exchange capacity to intercalate 5-FU into its interlayer spacing and load siRNA on the surface of LDH nanoparticles. LDH nanoparticles have been previously demonstrated as an effective cellular delivery system for 5-FU and siRNA separately in various investigations. More excitedly, the combination of CD-siRNA and anticancer drug 5-FU with the same LDH particles significantly enhanced cytotoxicity to three cancer cell lines, e.g. MCF-7, U2OS and HCT-116, compared to the single treatment with either CD-siRNA or 5-FU. This enhancement is probably a result of coordinate mitochondrial damage process. Thus, the strategy to co-deliver siRNA and an anticancer drug by LDHs has great potential to overcome the drug resistance and enhance cancer treatment

    Robust estimation of bacterial cell count from optical density

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    Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

    GENUS FORMULA FOR PROJECTIVE PLANE CURVES

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    Bachelor'sBACHELOR OF SCIENCE (HONOURS
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