•Service replacement cost method (SRCM) is established to access the UUS value.•Urban services provided by UUS is summarized.•A relative magnitude of the UUS value is obtained through case study.
...Urban underground space (UUS) has attracted more and more attention worldwide, but its value, external value particularly, is often ignored or underestimated, which will influence or even change the trade-offs in the decision-making processes of UUS development. This paper employed service replacement cost method (SRCM) to access the value of urban underground space. Since the precise estimate of the value of urban underground space is almost an impossible task, this paper can only provide a crude approximation, in other words, a relative magnitude of the value of urban underground space. The case study of Changzhou City in China manifested that urban underground space provided an important portion of urban economy, which reached up to, but not be limited to, 1.8% of its GDP. This paper should aid in giving urban underground space more weight in urban decision-making process.
•Proposed an evaluation method of spatial performance based on POI data.•Proposed supply-demand ratios of underground space development in Shanghai.•Identified the sub-districts of oversupply or ...undersupply of underground space.•Methods can be applied to compilation of master planning of underground space.
Master planning of urban underground space (UUS) is essential to guide orderly utilization of UUS. POI (point of interest) data from online maps provide a new data source for UUS research. This study proposed a simple framework to evaluate UUS development levels based on POI data. Evaluation methods of UUS spatial performance and development demand were established separately and then applied to the calculation of UUS supply-demand ratios of 217 sub-districts in Shanghai. The results showed that Huaihaizhonglu Sub-district achieved both the highest spatial performance and development demand values. The majority of the sub-districts with high or medium high performance values were situated in the central urban area. By comparison, the sub-districts with extremely low spatial performance clustered in the southern suburb and on Chongming Island. By means of Natural Breaks (Jenks) method, the sub-districts of oversupplied and undersupplied UUS development were figured out and then classified into five types to propose corresponding development strategies for future UUS utilization. The evaluation framework and results can give insights for more scientific and rational compilation of UUS master planning, especially for the metropolitan cities with a huge amount of developed UUS.
AbstractObjectiveTo review and summarise the evidence on the prevalence of colorectal adenomas and cancers at a follow-up screening colonoscopy after negative index colonoscopy, stratified by ...interval between examinations and by sex.DesignSystematic review and meta-analysis of all available studies.Data sourcesPubMed, Web of Science, and Embase. Two investigators independently extracted characteristics and results of identified studies and performed standardised quality ratings.Eligibility criteriaStudies assessing the outcome of a follow-up colonoscopy among participants at average risk for colorectal cancer with a negative previous colonoscopy (no adenomas).Results28 studies were identified, including 22 cohort studies, five cross sectional studies, and one case-control study. Findings for an interval between colonoscopies of one to five, five to 10, and more than 10 years were reported by 17, 16, and three studies, respectively. Summary estimates of prevalences of any neoplasm were 20.7% (95% confidence interval 15.8% to 25.5%), 23.0% (18.0% to 28.0%), and 21.9% (14.9% to 29.0%) for one to five, five to 10, and more than 10 years between colonoscopies. Corresponding summary estimates of prevalences of any advanced neoplasm were 2.8% (2.0% to 3.7%), 3.2% (2.2% to 4.1%), and 7.0% (5.3% to 8.7%). Seven studies also reported findings stratified by sex. Summary estimates stratified by interval and sex were consistently higher for men than for women.ConclusionsAlthough detection of any neoplasms was observed in more than 20% of participants within five years of a negative screening colonoscopy, detection of advanced neoplasms within 10 years was rare. Our findings suggest that 10 year intervals for colonoscopy screening after a negative colonoscopy, as currently recommended, may be adequate, but more studies are needed to strengthen the empirical basis for pertinent recommendations and to investigate even longer intervals.Study registrationProspero CRD42019127842.
The utilization of urban underground space (UUS) offers an effective solution to urban problems but may also negatively affect urban development. Therefore, UUS development needs better concerted ...guidelines to coordinate various urban systems and the multiple components of the underground world. Sustainable Development Goals (SDGs), which should be viewed as important yardsticks for UUS development, do not explicitly mention urban underground space, although many of them are affected by both the positive and negative consequences of its development. To fill this gap, this review lays the foundations of relevant UUS concepts and uses exemplary cases to reveal that 11 out of 17 SDGs can be linked with UUS uses. These linkages also manifest that land administration, integrated planning, architectural design, and construction technology are critical dimensions for increasing the contributions of UUS to the realization of SDGs. To achieve multi-disciplinary synergies among these four critical dimensions, a collaborative approach framework based on spatial data infrastructure is required. Thus, this work provides academics and practitioners with a holistic view of sustainable UUS development.
Design of experiment (DoE) techniques have been widely used in the field of chromatographic parameters optimization as a valuable tool. A systematic literature review of the available DoE techniques ...applied to the development of a chromatographic analysis method is presented in this paper. First, the most common available designs and the implementation steps of DoE are comprehensively introduced. Then the studies in recent 10 years for the application of DoE techniques in various chromatographic techniques are discussed, such as capillary electrophoresis, liquid chromatography, gas chromatography, thin‐layer chromatography, and high‐speed countercurrent chromatography. Current problems and future outlooks are finally given to provide a certain inspiration of research in the application of DoE techniques to the different chromatographic techniques field. This review contributes to a better understanding of the DoE techniques for the efficient optimization of chromatographic analysis conditions, especially for the analysis of complex systems, such as multicomponent drugs and natural products.
We present a new method to design miniaturized antennas using a corrugated microstrip (CM) line, which shows good slow wave characteristic in the required frequency band. To achieve good radiating ...behavior and low profile simultaneously, CM is employed as the resonating part of the antenna. The impact of the CM propagation constant on the antenna is discussed in detail. The miniaturized antenna is designed and measured to verify the feasibility of the design method. The measured results show that the proposed antenna can achieve a beamwidth of 70° in E-plane and 75° in H-plane with a gain tolerance of 3 dB, and the realized peak gain level at the central frequency is 5.15 dBi, which have good agreements to the expected designs. Such results indicate that the proposed antenna exhibits excellent radiation characteristics at the resonant mode. The effective size of the proposed miniaturized antenna is 0.16λ 0 ×0.16λ 0 ×0.04λ 0 at 9 GHz, in which λ 0 is the wavelength of the central frequency.
•Existing problems of assumptions adopt by Terzaghi theory were discussed.•The shear bands and distribution of vertical earth pressure were redefined.•An improved method to calculate the vertical ...earth pressure was proposed.
Previous studies on field monitoring data indicate that vertical earth pressure would be overestimated by the Terzaghi theory for a deeply buried shield tunnel, which is widely adopted in tunnel design. A kinematic mechanical model was proposed to evaluate its influence on vertical earth pressure and implementation into the finite element program in this paper. To investigate the vertical earth pressure, a numerical study using the commercial software of PLAXIS was conducted on the vertical earth pressure distribution on a single shield tunnel, considering different tunnel diameters and burial depths in sandy and clay layers, such as Shanghai soil strata. Based on finite element model results, the existing problems such as soil displacement around tunnel, earth pressure distribution, collapsed soil mass width and sliding friction in the Terzaghi loosening earth pressure formula for a sand layer were discussed. Then, a feasible calculation method for vertical earth pressure on the tunnel lining was proposed. Through comparisons between calculated results and field measurements, the improved formulas were verified, providing a reference for future designs of deep underground structures in Shanghai Soil Layers.
We propose to suppress high-power microwave pulses (HPMPs) using nonlinear dispersion and filtering natures of spoof surface plasmon polaritons (SSPPs). Frequency components of a short HPMP are ...distributed in time domain due to different group velocities and partly cutoff on SSPP transmission lines (TLs), leading to peak suppression of HPMP. To illustrate the protection mechanism in real microwave engineering, an SSPP mono-pulse antenna is designed. Sum and difference beam functions of the antenna are demonstrated by both simulations and experiments. For easy comparison, a microstrip mono-pulse antenna is also fabricated. HPMP incidences from the main lobe directions of the sum beam and difference beam are considered. Compared to the microstrip antenna, obvious suppression of HPMPs is observed in the SSPP mono-pulse antenna in different cases, which verifies the better performance to prevent HPMP damages by SSPPs. The proposed technology to suppress HPMPs by using SSPPs can find wide applications in radar and communication systems in the electronic warfare environment.
Rationale
Due to the special geographical location and climate of China, there are large differences in the chemical composition and content of Paederia scandens (PS) from different origins, which ...will have a large impact on its efficacy.
Methods
An efficient quality control method for PS was established by combining ultra‐high‐performance liquid chromatography (UPLC) and electrospray ionization mass spectrometry analyses. First, a UPLC‐quadrupole time‐of‐flight mass spectrometry system was employed to identify the chemical composition of PS from seven different origins. Then, the chemical variation in 73 batches of PS samples was subsequently investigated by quantitation of four marker compounds.
Results
A total of 15 common compounds were identified in the samples of PS from seven origins. And four of the marker compounds were chosen based on VIP values to characterize the differences between PS samples of different origins. The linearity ranged between 0.005 and 2.500 mg/mL; the correlation coefficients (r2) ranged from 0.999 to 1; the limits of detection ranged from 0.013 to 0.033 μg/mL; and the relative standard deviations for repeatability, precisions, and stabilities were below 0.2%, 1.6%, and 0.6%, respectively.
Conclusion
The results show that the method can be effective and comprehensive in evaluating the quality of PS from different origins. And this comprehensive strategy proved to be a powerful technique used to differentiate between different geographical herbs.
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