| 1. |
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| 2. |
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| 3. |
- 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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| 4. |
- Sampson, Joshua N., et al.
(författare)
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Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for 13 Cancer Types
- 2015
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 107:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.
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| 5. |
- Desjardins, Kewin, et al.
(författare)
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Characterization of a back-illuminated CMOS camera for soft x-ray coherent scattering
- 2019
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Ingår i: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
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Konferensbidrag (refereegranskat)abstract
- A commercial scientific camera has been adapted and characterized at the SOLEIL Synchrotron with the aim to improve the acquisition capabilities on the soft X-ray coherent scattering experimental station at SEXTANTS beamline. This device is equipped by the last generation of back side illuminated scientific CMOS (BSI-sCMOS) of 2048 by 2048 pixels of 11 μm2 able to acquire low noise images with a frame rate up to 48 Hz. The camera's performance measurements have been done and shows a good level of readout noise, a large full-well capacity, a medium dark current and a good homogeneity, respectively, 1.6 e- rms (in High Gain mode), 80 000 e- (in Low Gain mode),<5 e-/pixel/s and ∼ 1%. The quantum efficiency (QE) measurement has been performed at the soft x-ray branch of the METROLOGIE beamline and gives a relatively good agreement with the expected theoretical values. Finally, the demonstration of the camera's efficiency and of the gain in useful time measurement related to the high frame rate have been performed with a series of Airy patterns images compared with an image recorded using the standard BSI-CDD already in operation at the SEXTANTS beamline.
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| 6. |
- Griesmayer, E., et al.
(författare)
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Applications of single-crystal CVD diamond XBPM detectors with nanometre x-ray beams
- 2019
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Ingår i: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
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Konferensbidrag (refereegranskat)abstract
- Measurements with a Diamond XBPM were carried out at the MAX IV Laboratory, Lund, Sweden, at the NanoMAX beam line. This was the first investigation of a Diamond XBPM detector with nanometre beams. The effect of diffusion, as well as the position resolution at the smallest available beam sizes were studied.
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| 7. |
- Marcouille, O., et al.
(författare)
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Production of high energy photons with in vacuum wigglers : From SOLEIL wiggler to MAXIV wiggler
- 2019
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Ingår i: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
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Konferensbidrag (refereegranskat)abstract
- Small gap wigglers become more and more attractive to produce high photon fluxes in the hard X-ray photon range. They use magnet blocks of high magnetization which resists much better to heating (baking, synchrotron radiation) than in the past, produce high magnetic field with numerous periods and are very compact. They also are a very good alternative to superconducting technology which requires special infrastructure, heavy maintenance and is not running cost free. SOLEIL, operating presently at 2.75 GeV has designed and built an in-vacuum wiggler of 38 periods of 50 mm producing 2.1 T at a minimum gap of 5.5 mm to delivered photon beam between 20 keV and 50 keV. Already in operation, further improvements are presently in progress to push photons towards higher energy, in particular thanks to the operation at lower gap (4.5 mm). MAX IV and SOLEIL, in the frame of collaboration, ave built an upgraded version of the existing SOLEIL wiggler with the target to extend the spectral range at high energy (above 50 keV) but also at low energy (4 keV) with the same insertion device. The design of the existing magnetic system has been modified to reach 2.4 T at a minimum gap of 4.2 mm and includes taper operation to avoid undulator structure in the radiated spectrum at low energy.
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| 8. |
- Plivelic, Tomás S., et al.
(författare)
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X-ray tracing, design and construction of an optimized optics scheme for CoSAXS, the small angle x-ray scattering beamline at MAX IV laboratory
- 2019
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Ingår i: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
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Konferensbidrag (refereegranskat)abstract
- A novel optical design for a flexible SAXS beamline at a modern synchrotron has been implemented for the CoSAXS beamline at the 3GeV ring at the MAX TV Laboratory. The performance of the beamline has been simulated through combined ray tracing and wave propagation with the code xrt taking into account the low emittance and highly coherent beam of MAX TV and the short inter-optics distances of the beamline. The total photon flux is estimated to be 1012-1013 ph/s with the coherent flux portion up to 10 % at 7.1 keV. The inhomogeneities in the X-ray beam arising from use of real (non-idealised) mirror surfaces are also modelled using the measured slope profiles of the mirrors. Strategies to mitigate these inhomogeneities are discussed. The optical components for CoSAXS have been constructed and beamline commissioning will start in 2019.
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| 9. |
- Weinstein, John N., et al.
(författare)
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The cancer genome atlas pan-cancer analysis project
- 2013
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:10, s. 1113-1120
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Forskningsöversikt (refereegranskat)abstract
- The Cancer Genome Atlas (TCGA) Research Network has profiled and analyzed large numbers of human tumors to discover molecular aberrations at the DNA, RNA, protein and epigenetic levels. The resulting rich data provide a major opportunity to develop an integrated picture of commonalities, differences and emergent themes across tumor lineages. The Pan-Cancer initiative compares the first 12 tumor types profiled by TCGA. Analysis of the molecular aberrations and their functional roles across tumor types will teach us how to extend therapies effective in one cancer type to others with a similar genomic profile. © 2013 Nature America, Inc. All rights reserved.
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| 10. |
- Hua, Kuo-Tai, et al.
(författare)
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N-α-acetyltransferase 10 protein suppresses cancer cell metastasis by binding PIX proteins and inhibiting Cdc42/Rac1 activity
- 2011
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Ingår i: Cancer Cell. - : Cell Press. - 1535-6108 .- 1878-3686. ; 19:2, s. 218-231
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Tidskriftsartikel (refereegranskat)abstract
- N-α-acetyltransferase 10 protein, Naa10p, is an N-acetyltransferase known to be involved in cell cycle control. We found that Naa10p was expressed lower in varieties of malignancies with lymph node metastasis compared with non-lymph node metastasis. Higher Naa10p expression correlates the survival of lung cancer patients. Naa10p significantly suppressed migration, tumor growth, and metastasis independent of its enzymatic activity. Instead, Naa10p binds to the GIT-binding domain of PIX, thereby preventing the formation of the GIT-PIX-Paxillin complex, resulting in reduced intrinsic Cdc42/Rac1 activity and decreased cell migration. Forced expression of PIX in Naa10-transfected tumor cells restored the migration and metastasis ability. We suggest that Naa10p functions as a tumor metastasis suppressor by disrupting the migratory complex, PIX-GIT- Paxillin, in cancer cells.
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| 11. |
- Wu, Ping-Hsun, et al.
(författare)
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Exploring the Benefit of 2-Methylbutyric Acid in Patients Undergoing Hemodialysis Using a Cardiovascular Proteomics Approach
- 2019
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Ingår i: Nutrients. - : MDPI. - 2072-6643. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Short-chain fatty acids (SCFAs) can reduce pro-inflammatory parameters and oxidative stress, providing potential cardiovascular (CV) benefits. Although some evidence links SCFAs with host metabolic health via several biological mechanisms, the role of SCFA on CV disease in patients with kidney disease remains unclear. Herein, we investigate the association between a SCFA, 2-methylbutyric acid, and target CV proteomics to explore the potential pathophysiology of SCFA-related CV benefit in patients with kidney disease. Circulating 2-methylbutyric acid was quantified by high-performance liquid chromatography and 181 CV proteins by a proximity extension assay in 163 patients undergoing hemodialysis (HD). The associations between 2-methylbutyric acid and CV proteins were evaluated using linear regression analysis with age and gender, and multiple testing adjustment. The selected CV protein in the discovery phase was further confirmed in multivariable-adjusted models and evaluated by continuous scale association. The mean value of circulating 2-methylbutyric acid was 0.22 +/- 0.02 mu m which was negatively associated with bone morphogenetic protein 6 (BMP-6) according to the false discovery rate (FDR) multiple testing adjustment method. The 2-methylbutyric acid level remained negatively associated with BMP-6 (beta coefficient -1.00, 95% confidence interval -1.45 to -0.55, p < 0.001) after controlling for other CV risk factors in multivariable models. The cubic spline curve demonstrated a linear relationship. In conclusion, circulating 2-methylbutyric acid level was negatively associated with BMP-6, suggesting that this pathway maybe involved in vascular health in patients undergoing HD. However, further in vitro work is still needed to validate the translation of the mechanistic pathways.
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| 12. |
- Jian, Jhang-Jie, et al.
(författare)
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Investigation of Multiple-Mesa-Nanochannel Array GaN-Based MOSHEMTs with Al2O3 Gate Dielectric Layer
- 2021
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Ingår i: ECS Journal of Solid State Science and Technology. - : The Electrochemical Society. - 2162-8777 .- 2162-8769. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an atomic layer deposition system was used to deposit Al2O3 high-k dielectric film as the gate insulator of GaN-based metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs). By using the Al2O3 gate dielectric layer, compared to planar channel structure, the direct current, high frequency, and flicker noise performances were improved in the GaN-based MOSHEMTs with fin-nanochannel array. For the GaN-based 80-nm-wide fin-nanochannel array MOSHEMTs, they exhibited superior performances of maximum extrinsic transconductance of 239 mS mm(-1), threshold voltage of -0.4 V, unit gain cutoff frequency of 7.3 GHz, maximum oscillation frequency of 14.1 GHz, normalized noise power of 2.5 x 10(-14) Hz(-1), and Hooge's coefficient of 1.4 x 10(-6). The enhanced performances were attributed to the features of fin-nanochannel array of better gate control capability, enhanced pinch-off effect, and better heat dissipation driven by lateral heat flow within the space between fin-channels.
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| 13. |
- Lee, Hsin Ying, et al.
(författare)
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Fabrication and Characterization of GaN-Based Fin-Channel Array Metal-Oxide-Semiconductor High-Electron Mobility Transistors with Recessed-Gate and Ga2O3 Gate Insulator Layer
- 2021
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Ingår i: IEEE Journal of the Electron Devices Society. - 2168-6734. ; 9, s. 393-399
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the properties of gallium oxide (Ga2O3) and its excellent interface properties to GaN-based materials are explored as a gate insulator layer for GaN-based metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs). A novel vapor cooling condensation system was used to deposit the high quality Ga2O3 films with high insulation and low defect suitable for gate insulator layer. The characteristics of the Ga2O3 films were further explored by implementing GaN-based fin-channel array MOSHEMTs with recessed-gates and different channel widths. Compared to planar channel structure, the direct current, high frequency, and flicker noise performances were enhanced in the fin-channel MOSHEMTs with Ga2O3 gate insulator layer. For the GaN-based fin-channel array MOSHEMTs with 300-nm-wide channel, the devices exhibited superior performances of maximum extrinsic transconductance of 194.2 mS/mm, threshold voltage of.1.4 V, extrinsic unit gain cutoff frequency of 6.4 GHz, maximum oscillation frequency of 14.8 GHz, and normalized noise power of 8.45 × 10.15 Hz.1. It was also demonstrated that the associated performances were improved by reducing the width of fin-channel array.
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| 14. |
- Tai, Chi-Jung, et al.
(författare)
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Prediction of Frailty and Dementia Using Oral Health Impact Profile from a Population-Based Survey
- 2020
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 17:6
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Tidskriftsartikel (refereegranskat)abstract
- Oral health and dentition have been associated with cognitive ability and frailty, but an applicable screening tool has not yet been developed. This study aimed to establish risk prediction models for dementia and frailty. A sample of 2905 community-dwelling older adults aged >= 58 years using the Taiwan Longitudinal Study on Aging (TLSA) survey was adapted and analyzed for this study. Risk scores were estimated by stepwise logistic regression. In models adjusted for covariates, increased age, female sex, no dental prosthesis (adjusted Odds ratio [adjOR], 1.61; 95% confidence interval [CI], 1.11-2.35), diabetes mellitus, chronic kidney disease, and an increased Oral Health Impact Profile (OHIP)-7T Q3 score (adjOR, 1.33; 95% CI, 1.19-1.49) were all significantly associated with frailty. In addition to these factors, an inability to self-report height or weight (adjOR, 4.52; 95% CI, 3.52-5.81) and an increased OHIP-7T Q7 score (adjOR, 1.21; 95% CI, 1.06-1.37) were significantly associated with dementia. The cut-off points of the risk scores for frailty and dementia were 80 (sensitivity, 80.0%; specificity, 81.2%) and 77 (sensitivity, 83.4%; specificity, 71.5%), respectively. The findings highlighted a number of composite risk factors of frailty and dementia. Importantly, the developed prediction models were easily applicable to screen for frailty and dementia in communities or dental clinics.
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| 15. |
- Amann, Peter, et al.
(författare)
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A dedicated photoelectron spectroscopy instrument for studies of catalytic reactions at pressures exceeding 1 bar
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Here, we present a new high-pressure x-ray photoelectron spectroscopy system dedicated to probing catalytic reactions under realistic conditions at pressures exceeding 1 bar. The instrument builds around the concept of a “virtual cell” in which a gasflow is directed onto the sample surface creating a local high pressure on top of the sample. This allows the instrument to maintain a low pressure of a few mbars in the main chamber, while simultaneously keeping a local pressure of around 1 bar. Synchrotron radiation based grazing incidence photoemission within ± 5° is used to enhance the surface sensitivity in the experiment. The aperture, separating the high-pressure region from the differential pumping of the electron spectrometer, consists of multiple, evenly spaced, mm sized holes matching the footprint of the x-ray beam on the sample surface. As the photo-emitted electrons are subject to strong scattering in the gas phase and the resulting signal is therefore highly dependent on the sample to aperture distance, the latter is controlled with high precision using a fully integrated manipulator that allows for sample movement with step sizes of 10 nm between 0 and –5 mm with very low vibrational amplitude. The instrumental features allows acquisition of metallic bulk spectra at He pressures up to 2.5 bar and also allows for following C1s spectra under realistic gas mixtures of CO + H2with various temperatures up to 500°C. This capability opens for studies of catalytic reactions in operandi.
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| 16. |
- Amann, Peter, et al.
(författare)
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A high-pressure x-ray photoelectron spectroscopy instrument for studies of industrially relevant catalytic reactions at pressures of several bars
- 2019
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 90:10
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Tidskriftsartikel (refereegranskat)abstract
- We present a new high-pressure x-ray photoelectron spectroscopy system dedicated to probing catalytic reactions under realistic conditions at pressures of multiple bars. The instrument builds around the novel concept of a "virtual cell" in which a gas flow onto the sample surface creates a localized high-pressure pillow. This allows the instrument to be operated with a low pressure of a few millibar in the main chamber, while simultaneously a local pressure exceeding 1 bar can be supplied at the sample surface. Synchrotron based hard x-ray excitation is used to increase the electron mean free path in the gas region between sample and analyzer while grazing incidence <5 degrees close to total external refection conditions enhances surface sensitivity. The aperture separating the high-pressure region from the differential pumping of the electron spectrometer consists of multiple, evenly spaced, micrometer sized holes matching the footprint of the x-ray beam on the sample. The resulting signal is highly dependent on the sample-to-aperture distance because photoemitted electrons are subject to strong scattering in the gas phase. Therefore, high precision control of the sample-to-aperture distance is crucial. A fully integrated manipulator allows for sample movement with step sizes of 10 nm between 0 and -5 mm with very low vibrational amplitude and also for sample heating up to 500 degrees C under reaction conditions. We demonstrate the performance of this novel instrument with bulk 2p spectra of a copper single crystal at He pressures of up to 2.5 bars and C1s spectra measured in gas mixtures of CO + H-2 at pressures of up to 790 mbar. The capability to detect emitted photoelectrons at several bars opens the prospect for studies of catalytic reactions under industrially relevant operando conditions.
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| 17. |
- Andersson, Bo, Docent, 1965-, et al.
(författare)
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Enhancing Information Quality as Part of the Disease Surveillance System in Malawi, Africa : Reflections on a mHealth Intervention
- 2017
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Ingår i: Information Systems Development: Advances in Methods, Tools and Management. - Larnaca : Association for Information Systems. - 9789963228836
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Konferensbidrag (refereegranskat)abstract
- Public health surveillance and response to disease outbreaks is still a hurdle in many developing countries across sub-Saharan Africa. Pivotal in disease surveillance and response is the reliance on valid information, hence, the need for information which has high Information Quality (IQ) characteristics. A key issue with disease surveillance systems, stem from the diverse range of data sources with various levels of information quality that may affect the trustworthiness of the information. However, with the increasing diffusion of mobile phone technologies, there are opportunities to improve IQ. The aim of this study was to assess the information quality in data collected through a smartphone application. Based on qualitative data from interviews, workshop and system specifications, it was found that information quality improves with the use of smartphone applications but aspects such as user competence and trustworthiness, must be addressed to maximize the benefits of using mobile technologies for disease surveillance.
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| 18. |
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| 19. |
- Chirambo, Griphin Baxter, et al.
(författare)
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Effectiveness of Smartphone-Based Community Case Management on the Urgent Referral, Reconsultation, and Hospitalization of Children Aged Under 5 Years in Malawi : Cluster-Randomized, Stepped-Wedge Trial
- 2021
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Ingår i: Journal of Medical Internet Research. - : JMIR Publications. - 1438-8871. ; 23:10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Integrated community case management (CCM) has led to reductions in child mortality in Malawi resulting from illnesses such as malaria, pneumonia, and diarrhea. However, adherence to CCM guidelines is often poor, potentially leading to inappropriate clinical decisions and poor outcomes. We determined the impact of an e-CCM app on the referral, reconsultation, and hospitalization rates of children presenting to village clinics in Malawi.OBJECTIVE: We determined the impact of an electronic version of a smartphone-based CCM (e-CCM) app on the referral, reconsultation, and hospitalization rates of children presenting to village clinics in Malawi.METHODS: We used a stepped-wedge, cluster-randomized trial to compare paper-based CCM (control) with and without the use of an e-CCM app on smartphones from November 2016 to February 2017. A total of 102 village clinics from 2 districts in northern Malawi were assigned to 1 of 6 clusters, which were randomized on the sequencing of the crossover from the control phase to the intervention phase as well as the duration of exposure in each phase. Children aged ≥2 months to <5 years who presented with acute illness were enrolled consecutively by health surveillance assistants. The primary outcome of urgent referrals to higher-level facilities was evaluated by using multilevel mixed effects models. A logistic regression model with the random effects of the cluster and the fixed effects for each step was fitted. The adjustment for potential confounders included baseline factors, such as patient age, sex, and the geographical location of the village clinics. Calendar time was adjusted for in the analysis.RESULTS: A total of 6965 children were recruited-49.11% (3421/6965) in the control phase and 50.88% (3544/6965) in the intervention phase. After adjusting for calendar time, children in the intervention phase were more likely to be urgently referred to a higher-level health facility than children in the control phase (odds ratio [OR] 2.02, 95% CI 1.27-3.23; P=.003). Overall, children in the intervention arm had lower odds of attending a repeat health surveillance assistant consultation (OR 0.45, 95% CI 0.34-0.59; P<.001) or being admitted to a hospital (OR 0.75, 95% CI 0.62-0.90; P=.002), but after adjusting for time, these differences were not significant (P=.07 for consultation; P=.30 for hospital admission).CONCLUSIONS: The addition of e-CCM decision support by using smartphones led to a greater proportion of children being referred to higher-level facilities, with no apparent increase in hospital admissions or repeat consultations in village clinics. Our findings provide support for the implementation of e-CCM tools in Malawi and other low- and middle-income countries with a need for ongoing assessments of effectiveness and integration with national digital health strategies.TRIAL REGISTRATION: ClinicalTrials.gov NCT02763345; https://clinicaltrials.gov/ct2/show/NCT02763345.
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| 20. |
- Hsiung, Te-Chih, et al.
(författare)
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Enhanced surface mobility and quantum oscillations in topological insulator Bi1.5Sb0.5Te1.7Se1.3 nanoflakes
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:16
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Tidskriftsartikel (refereegranskat)abstract
- n this study, a series of Bi1.5Sb0.5Te 1.7Se1.3 (BSTS) flakes 80-nm to 140-μm in thickness was fabricated to investigate their metallic surface states. We report the observation of surface-dominated transport in these topological insulator BSTS nanoflakes. The achievement of surface-dominated transport can be attributed to high surface mobility (∼3000 cm2/V s) and low bulk mobility (12 cm2/V s). Up to 90% of the total conductance, the surface channel was estimated based on the thickness dependence of electrical conductance and the result of the Shubnikov-de Hass oscillations in a 200-nm BSTS. The nature of nontrivial Dirac surface states was also confirmed by the weak anti-localization effect.
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| 21. |
- Minelli, Caterina, et al.
(författare)
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Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
- 2022
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 14, s. 4690-4704
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Tidskriftsartikel (refereegranskat)abstract
- We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles.
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