| 1. |
- Bellm, Eric C., et al.
(författare)
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The Zwicky Transient Facility : System Overview, Performance, and First Results
- 2019
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:995
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Tidskriftsartikel (refereegranskat)abstract
- The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg(2) field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope.
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| 2. |
- Bunzli, Samantha, et al.
(författare)
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Placebo Surgery Controlled Trials : Do They Achieve What They Set Out To Do? A Systematic Review
- 2021
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Ingår i: Annals of Surgery. - 1528-1140. ; 273:6, s. 1102-1107
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To explore whether placebo surgery controlled trials achieve what they set out to do by investigating discrepancy between projected and actual design aspects of trials identified through systematic review methods. SUMMARY BACKGROUND: Interest in placebo surgery controlled trials is growing in response to concerns regarding unnecessary surgery and the societal cost of low-value healthcare. As questions about the justifiability of using placebo controls in surgery have been addressed, attention is now being paid to more practical concerns. METHODS: Six databases were searched from inception - May 2020 (MEDLINE, Embase, Emcare, APA PsycInfo, CINAHL, Cochrane Library). Placebo surgery controlled trials with a published protocol were included. Three authors extracted "projected" design aspects from protocols and "actual" design aspects from main findings papers. Absolute and relative difference between projected and actual design aspects were presented for each trial. Trials were grouped according to whether they met their target sample size ("completed") and were concluded in a timely fashion. Pairs of authors assessed risk of bias. RESULTS: Of 24 trials with data available to analyse; 3 were completed and concluded within target timeframe; 10 were completed and concluded outside the target timeline; 4 were completed without clear target timeframes; 2 were incomplete and concluded within the target framework; 5 were incomplete and concluded outside the target timeline. Trials which reached the recruitment target underestimated trial duration by 88% and number of recruitment sites by 87%. CONCLUSIONS: Trialists need to factor additional time and sites into future placebo surgery controlled trials. A robust reporting framework of projected and actual trial design is imperative for trialists to learn from their predecessors. REVIEW REGISTRATION: PROSPERO (CRD42019133296).
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| 3. |
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| 4. |
- Bellm, Eric C., et al.
(författare)
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The Zwicky Transient Facility : Surveys and Scheduler
- 2019
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 131:1000
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel algorithm for scheduling the observations of time-domain imaging surveys. Our integer linear programming approach optimizes an observing plan for an entire night by assigning targets to temporal blocks, enabling strict control of the number of exposures obtained per field and minimizing filter changes. A subsequent optimization step minimizes slew times between each observation. Our optimization metric self-consistently weights contributions from time-varying airmass, seeing, and sky brightness to maximize the transient discovery rate. We describe the implementation of this algorithm on the surveys of the Zwicky Transient Facility and present its on-sky performance.
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| 5. |
- Butina, Karen, et al.
(författare)
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Optotracing for selective fluorescence-based detection, visualization and quantification of live S. aureus in real-time
- 2020
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Ingår i: npj Biofilms and Microbiomes. - : Nature Research. - 2055-5008. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Methods for bacterial detection are needed to advance the infection research and diagnostics. Based on conformation-sensitive fluorescent tracer molecules, optotracing was recently established for dynamic detection and visualization of structural amyloids and polysaccharides in the biofilm matrix of gram-negative bacteria. Here, we extend the use of optotracing for detection of gram-positive bacteria, focussing on the clinically relevant opportunistic human pathogen Staphylococcus aureus. We identify a donor-acceptor-donor-type optotracer, whose binding-induced fluorescence enables real-time detection, quantification, and visualization of S. aureus in monoculture and when mixed with gram-negative Salmonella Enteritidis. An algorithm-based automated high-throughput screen of 1920 S. aureus transposon mutants recognized the cell envelope as the binding target, which was corroborated by super-resolution microscopy of bacterial cells and spectroscopic analysis of purified cell wall components. The binding event was essentially governed by hydrophobic interactions, which permitted custom-designed tuning of the binding selectivity towards S. aureus versus Enterococcus faecalis by appropriate selection of buffer conditions. Collectively this work demonstrates optotracing as an enabling technology relevant for any field of basic and applied research, where visualization and detection of S. aureus is needed.
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| 6. |
- Butina, Karen, et al.
(författare)
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Structural Properties Dictating Selective Optotracer Detection of Staphylococcus aureus
- 2022
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Ingår i: ChemBioChem. - : Wiley. - 1439-4227 .- 1439-7633. ; 23:11
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Tidskriftsartikel (refereegranskat)abstract
- Optotracers are conformation-sensitive fluorescent tracer molecules that detect peptide- and carbohydrate-based biopolymers. Their binding to bacterial cell walls allows selective detection and visualisation of Staphylococcus aureus (S. aureus). Here, we investigated the structural properties providing optimal detection of S. aureus. We quantified spectral shifts and fluorescence intensity in mixes of bacteria and optotracers, using automatic peak analysis, cross-correlation, and area-under-curve analysis. We found that the length of the conjugated backbone and the number of charged groups, but not their distribution, are important factors for selective detection of S. aureus. The photophysical properties of optotracers were greatly improved by incorporating a donor-acceptor-donor (D-A-D)-type motif in the conjugated backbone. With significantly reduced background and binding-induced on-switch of fluorescence, these optotracers enabled real-time recordings of S. aureus growth. Collectively, this demonstrates that chemical structure and photophysics are key tunable characteristics in the development of optotracers for selective detection of bacterial species.
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| 7. |
- Choong, FX, et al.
(författare)
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Real-time optotracing of curli and cellulose in live Salmonella biofilms using luminescent oligothiophenes
- 2016
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Ingår i: NPJ biofilms and microbiomes. - : Springer Science and Business Media LLC. - 2055-5008. ; 2, s. 16024-
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular matrix (ECM) is the protein- and polysaccharide-rich backbone of bacterial biofilms that provides a defensive barrier in clinical, environmental and industrial settings. Understanding the dynamics of biofilm formation in native environments has been hindered by a lack of research tools. Here we report a method for simultaneous, real-time, in situ detection and differentiation of the Salmonella ECM components curli and cellulose, using non-toxic, luminescent conjugated oligothiophenes (LCOs). These flexible conjugated polymers emit a conformation-dependent fluorescence spectrum, which we use to kinetically define extracellular appearance of curli fibres and cellulose polysaccharides during bacterial growth. The scope of this technique is demonstrated by defining biofilm morphotypes of Salmonella enterica serovars Enteritidis and Typhimurium, and their isogenic mutants in liquid culture and on solid media, and by visualising the ECM components in native biofilms. Our reported use of LCOs across a number of platforms, including intracellular cellulose production in eukaryotic cells and in infected tissues, demonstrates the versatility of this optotracing technology, and its ability to redefine biofilm research.
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| 8. |
- Choong, Ferdinand X., et al.
(författare)
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Nondestructive, real-time determination and visualization of cellulose, hemicellulose and lignin by luminescent oligothiophenes
- 2016
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Enabling technologies for efficient use of the bio-based feedstock are crucial to the replacement of oil-based products. We investigated the feasibility of luminescent conjugated oligothiophenes (LCOs) for non-destructive, rapid detection and quality assessment of lignocellulosic components in complex biomass matrices. A cationic pentameric oligothiophene denoted p-HTEA (pentamer hydrogen thiophene ethyl amine) showed unique binding affinities to cellulose, lignin, hemicelluloses, and cellulose nanofibrils in crystal, liquid and paper form. We exploited this finding using spectrofluorometric methods and fluorescence confocal laser scanning microscopy, for sensitive, simultaneous determination of the structural and compositional complexities of native lignocellulosic biomass. With exceptional photostability, p-HTEA is also demonstrated as a dynamic sensor for real-time monitoring of enzymatic cellulose degradation in cellulolysis. These results demonstrate the use of p-HTEA as a non-destructive tool for the determination of cellulose, hemicellulose and lignin in complex biomass matrices, thereby aiding in the optimization of biomass-converting technologies.
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| 9. |
- Choong, Ferdinand X., et al.
(författare)
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Stereochemical Identification of Glucans by a Donor-Acceptor-Donor Conjugated Pentamer Enables Multi-Carbohydrate Anatomical Mapping in Plant Tissues
- 2019
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Ingår i: Cellulose. - : Springer Netherlands. - 0969-0239 .- 1572-882X. ; 26:7, s. 4253-4264
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Tidskriftsartikel (refereegranskat)abstract
- Optotracing is a novel method for analytical imaging of carbohydrates in plant and microbial tissues. This optical method applies structure-responsive oligothiophenes as molecular fluorophores emitting unique optical signatures when bound to polysaccharides. Herein, we apply Carbotrace680, a short length anionic oligothiophene with a central heterocyclic benzodithiazole (BTD) motif, to probe for different glucans. The donor-acceptor-donor type electronic structure of Carbotrace680 provides improved spectral properties compared to oligothiophenes due to the possibility of intramolecular charge-transfer transition to the BTD motif. This enables differentiation of glucans based on the glycosidic linkage stereochemistry. Thus -configured starch is readily differentiated from -configured cellulose. The versatility of optotracing is demonstrated by dynamic monitoring of thermo-induced starch remodelling, shown in parallel by spectrophotometry and microscopy of starch granules. Imaging of Carbotrace680 bound to multiple glucans in plant tissues provided direct identification of their physical locations, revealing the spatial relationship between structural (cellulose) and storage (starch) glucans at sub-cellular scale. Our work forms the basis for the development of superior optotracers for sensitive detection of polysaccharides. Our non-destructive method for anatomical mapping of glucans in biomass will serve as an enabling technology for developments towards efficient use of plant-derived materials and biomass.
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| 10. |
- Choong, Ferdinand X., et al.
(författare)
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Stereochemical identification of glucans by oligothiophenes enables cellulose anatomical mapping in plant tissues
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Efficient use of plant-derived materials requires enabling technologies for non-disruptive composition analysis. The ability to identify and spatially locate polysaccharides in native plant tissues is difficult but essential. Here, we develop an optical method for cellulose identification using the structure-responsive, heptameric oligothiophene h-FTAA as molecular fluorophore. Spectrophotometric analysis of h-FTAA interacting with closely related glucans revealed an exceptional specificity for beta-linked glucans. This optical, non-disruptive method for stereochemical differentiation of glycosidic linkages was next used for in situ composition analysis in plants. Multi-laser/multi-detector analysis developed herein revealed spatial localization of cellulose and structural cell wall features such as plasmodesmata and perforated sieve plates of the phloem. Simultaneous imaging of intrinsically fluorescent components revealed the spatial relationship between cell walls and other organelles, such as chloroplasts and lignified annular thickenings of the trachea, with precision at the sub-cellular scale. Our non-destructive method for cellulose identification lays the foundation for the emergence of anatomical maps of the chemical constituents in plant tissues. This rapid and versatile method will likely benefit the plant science research fields and may serve the biorefinery industry as reporter for feedstock optimization as well as in-line monitoring of cellulose reactions during standard operations.
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