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| 2. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Zhang, Yongjin, et al.
(författare)
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An integrated approach to estimate storage reliability with initial failures based on E-Bayesian estimates
- 2017
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Ingår i: Reliability Engineering & System Safety. - : Elsevier BV. - 0951-8320 .- 1879-0836. ; 159, s. 24-36
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Tidskriftsartikel (refereegranskat)abstract
- Storage reliability that measures the ability of products in a dormant state to keep their required functions is studied in this paper. For certain types of products, Storage reliability may not always be 100% at the beginning of storage, unlike the operational reliability, which exist possible initial failures that are normally neglected in the models of storage reliability. In this paper, a new integrated technique, the non-parametric measure based on the E-Bayesian estimates of current failure probabilities is combined with the parametric measure based on the exponential reliability function, is proposed to estimate and predict the storage reliability of products with possible initial failures, where the non-parametric method is used to estimate the number of failed products and the reliability at each testing time, and the parameter method is used to estimate the initial reliability and the failure rate of storage product. The proposed method has taken into consideration that, the reliability test data of storage products containing the unexamined before and during the storage process, is available for providing more accurate estimates of both the initial failure probability and the storage failure probability. When storage reliability prediction that is the main concern in this field should be made, the non-parametric estimates of failure numbers can be used into the parametric models for the failure process in storage. In the case of exponential models, the assessment and prediction method for storage reliability is presented in this paper. Finally, a numerical example is given to illustrate the method. Furthermore, a detailed comparison between the proposed and traditional method, for examining the rationality of assessment and prediction on the storage reliability, is investigated. The results should be useful for planning a storage environment, decision-making concerning the maximum length of storage, and identifying the production quality.
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| 4. |
- Tian, Ye, et al.
(författare)
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Holocene climate change in southern Oman deciphered by speleothem records and climate model simulations
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Qunf Cave oxygen isotope (& delta;O-18(c)) record from southern Oman is one of the most significant of few Holocene Indian summer monsoon cave records. However, the interpretation of the Qunf & delta;O-18(c) remains in dispute. Here we provide a multi-proxy record from Qunf Cave and climate model simulations to reconstruct the Holocene local and regional hydroclimate changes. The results indicate that besides the Indian summer monsoon, the North African summer monsoon also contributes water vapor to southern Oman during the early to middle Holocene. In principle, Qunf & delta;O-18(c) values reflect integrated oxygen-isotope fractionations over a broad moisture transport swath from moisture sources to the cave site, rather than local precipitation amount alone, and thus the Qunf & delta;O-18(c) record characterizes primary changes in the Afro-Asian monsoon regime across the Holocene. In contrast, local climate proxies appear to suggest an overall slightly increased or unchanged wetness over the Holocene at the cave site. Southern Oman speleothem oxygen isotope and multi-proxy data reveal diverse changes in the Afro-Indian summer monsoon circulations and local hydroclimate conditions during the Holocene, confirming climate model simulations.
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| 5. |
- Zhang, Yongjin, et al.
(författare)
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Dynamic and steady-state performance analysis for multi-state repairable reconfigurable manufacturing systems with buffers
- 2020
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Ingår i: European Journal of Operational Research. - : Elsevier. - 0377-2217 .- 1872-6860. ; 283:2, s. 491-510
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Tidskriftsartikel (refereegranskat)abstract
- Reconfigurable manufacturing systems (RMSs) are considered the solution of choice when variable production capacity and functionality are required. A combinational approach, which integrates the steady-state probabilities of repairable reconfigurable machine tools (RMTs) and inventory-state probabilities of buffers through an improved universal generating function, is introduced in this study to assess the compound performance indicators (CPIs) of a repairable RMS. This paper contributes to the existing literature by considering the availability of buffers to calculate the CPIs of an RMS. In the proposed approach, the dynamic-state probability for each RMT is determined with a homogeneous continuous-time Markov model, and steady-state probability is obtained as the limit of the dynamic probability as time tends to infinity. In addition, a descriptive input-output information flow, which combines the conveying processes of the machined parts through buffers with the Poisson process, is proposed to determine the inventory-state probabilities of the buffers. Moreover, the explicit expressions of the CPI and expected performance rate (for the RMS and its constituent RMTs) are determined, and the validation procedure and technical details of the performance analysis for the Monte Carlo simulation are presented. Finally, a non-serial, repairable, multi-state RMS with multiple buffers that produces three types of engine cylinder heads is presented to validate the proposed approach. The simulation results verify the accuracy of the performance assessment of the RMS. It is useful for performance improvement in terms of machine reliability, resource utilisation efficiency, and decision-making concerning the configuration of RMS with buffers.
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| 6. |
- Cheng, Hai, et al.
(författare)
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Milankovitch theory and monsoon
- 2022
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Ingår i: The Innovation. - : Elsevier BV. - 2666-6758. ; 3:6
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Forskningsöversikt (refereegranskat)abstract
- The widely accepted “Milankovitch theory” explains insolation-induced waxing and waning of the ice sheets and their effect on the global climate on orbital timescales. In the past half century, however, the theory has often come under scrutiny, especially regarding its “100-ka problem.” Another drawback, but the one that has received less attention, is the “monsoon problem,” which pertains to the exclusion of monsoon dynamics in classic Milankovitch theory even though the monsoon prevails over the vast low-latitude (∼30° N to ∼30° S) region that covers half of the Earth's surface and receives the bulk of solar radiation. In this review, we discuss the major issues with the current form of Milankovitch theory and the progress made at the research forefront. We suggest shifting the emphasis from the ultimate outcomes of the ice volume to the causal relationship between changes in northern high-latitude insolation and ice age termination events (or ice sheet melting rate) to help reconcile the classic “100-ka problem.” We discuss the discrepancies associated with the characterization of monsoon dynamics, particularly the so-called “sea-land precession-phase paradox” and the “Chinese 100-ka problem.” We suggest that many of these discrepancies are superficial and can be resolved by applying a holistic “monsoon system science” approach. Finally, we propose blending the conventional Kutzbach orbital monsoon hypothesis, which calls for summer insolation forcing of monsoons, with Milankovitch theory to formulate a combined “Milankovitch-Kutzbach hypothesis” that can potentially explain the dual nature of orbital hydrodynamics of the ice sheet and monsoon systems, as well as their interplays and respective relationships with the northern high-latitude insolation and inter-tropical insolation differential.
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| 7. |
- Comas-Bru, Laia, et al.
(författare)
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Evaluating model outputs using integrated global speleothem records of climate change since the last glacial
- 2019
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 15:4, s. 1557-1579
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Tidskriftsartikel (refereegranskat)abstract
- Although quantitative isotope data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which to achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercomparison Project Phase 6, so it is timely to evaluate different approaches to using the speleothem data for data-model comparisons. Here, we illustrate this using 456 globally distributed speleothem delta O-18 records from an updated version of the Speleothem Isotopes Synthesis and Analysis (SISAL) database and palaeoclimate simulations generated using the ECHAM5-wiso isotope-enabled atmospheric circulation model. We show that the SISAL records reproduce the first-order spatial patterns of isotopic variability in the modern day, strongly supporting the application of this dataset for evaluating model-derived isotope variability into the past. However, the discontinuous nature of many speleothem records complicates the process of procuring large numbers of records if data-model comparisons are made using the traditional approach of comparing anomalies between a control period and a given palaeoclimate experiment. To circumvent this issue, we illustrate techniques through which the absolute isotope values during any time period could be used for model evaluation. Specifically, we show that speleothem isotope records allow an assessment of a model's ability to simulate spatial isotopic trends. Our analyses provide a protocol for using speleothem isotope data for model evaluation, including screening the observations to take into account the impact of speleothem mineralogy on delta O-18 values, the optimum period for the modern observational baseline and the selection of an appropriate time window for creating means of the isotope data for palaeo-time-slices.
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| 8. |
- Kang, Shuting, et al.
(författare)
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ECSAS : Exploring critical scenarios from action sequence in autonomous driving
- 2023
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Ingår i: Proceeding of 2023 IEEE 32nd Asian Test Symposium (ATS). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Rare critical scenarios are crucial to verify the performance of autonomous driving in different situations. Critical scenario generation requires the ability of sampling critical combinations from an infinite parameter space in the logical scenario. Existing solutions aim to explore the correlation of action parameters in the initial scenario rather than action sequences. How to model action sequences so that one can further consider the effects of different action parameters is the bottleneck of the problem. In this paper, we solve the problem by proposing the ECSAS framework. Specifically, we first propose a description language, BTScenario, allowing us to model action sequences of scenarios. We then use reinforcement learning to search for combinations of critical action parameters. Several optimizations are proposed to increase efficiency, including action mask and replay buffer. Experimental results show that our model with strong collision ability and effectively outperforms the existing methods on various nontrivial scenarios.
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| 9. |
- Li, Kexue, et al.
(författare)
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Directional emissions from perovskite nanocrystals thin film enabled by metasurface integration through one step spin-coating process
- 2023
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Ingår i: Nano Research. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 16:5, s. 7646-7653
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Tidskriftsartikel (refereegranskat)abstract
- Advances in thin film light-emitting devices have fueled the rapid growth of a new class of solid-state lighting devices, featuring low fabrication cost, high quantum efficiency, and broadband spectrum coverage, etc. In contrast to the conventional inorganic semiconductors that rely on lattice matched high crystalline quality substrate, solution processable thin films eliminate the dependence on the substrate, which is highly desired for the ease and versatility of integrations with foreign medium. By taking this advantage, this work developed an ultracompact solution to control the directionality of thin film emitters using integrated dielectric metasurface through one step spin-coating process. As a proof of concept, directional emissions from perovskite nanocrystal thin film, including collimated light emissions and two-dimensional beam steering, are experimentally demonstrated. Notably, our approach, where light emitters were integrated on the back side of substrate after the fabrication of metasurface, judiciously avoids any potential degradation of material optical quality caused by the multi-step nanofabrication. Therefore, it can serve as a generalized scheme to engage the advantageous properties of dielectric metasurface, including the compactness, high efficiency, and beam controllability with the emerging thin film light-emitting diodes (LEDs), which is applicable to a wide range of solution processable materials, including organic light-emitting diodes, quantum-dot light emitting diodes, polymer LEDs, and perovskite LEDs, opening up new pathways to develop low-cost and ultra-compact solid state light sources with versatile beams characteristics. [Figure not available: see fulltext.].
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| 10. |
- Ma, Delong, et al.
(författare)
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The role of deep-seated half-grabens in the evolution of Huoerguosi-Manasi-Tugulu fold-and-thrust belt, northern Tian Shan, China
- 2019
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Ingår i: Journal of Geodynamics. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0264-3707 .- 1879-1670. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- The Huoerguosi-Manasi-Tugulu fold-and-thrust belt, which is located in the southern Junggar Basin, has formed in response to contraction during Late Cenozoic. However, the tectonic environment for its formation before Late Cenozoic is still controversial. In this paper, we use surface data, recently collected and processed subsurface seismic refection data, isopach map of Lower Jurassic and balanced sections to propose pre-existing half-graben system developed in the Lower Jurassic with this fold-and-thrust belt. We also use results of a series of scaled sandbox analogue models, where industrial CT apparatus was used to monitor deformation, to simulate the evolution of this fold-and-thrust belt. We suggest that the segmented shape of the Huoerguosi-Manasi-Tugulu fold-and-thrust belt is a response to the presence of thrust ramps, which were formed during Early Jurassic. During Late Cenozoic shortening, the Lower Jurassic syn-rift sediments served as major detachment horizon, making a pre-existing normal fault act as a stress concentration zone leading to steeping of a thrust-ramp over the normal fault and cover detachment overstep the underlying half-grabens. Modeling results reveal that the presented structural framework has close resemblance with paleostructures especially in the intracontinental environment, which underwent a complex multicycle evolution process, and provide a new prospective for the interpretation of natural examples.
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