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| 2. |
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| 3. |
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| 4. |
- Sardh, E, et al.
(författare)
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Overall Health, Daily Functioning, and Quality of Life in Acute Hepatic Porphyria Patients: ENVISION, a Phase 3 Global, Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial
- 2020
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Ingår i: DIGESTIVE AND LIVER DISEASE. - : Elsevier BV. - 1590-8658. ; 52, s. E35-E35
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Zelenina, A., et al.
(författare)
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Silicon nanocrystals in SiNx/SiO2 hetero-superlattices : The loss of size control after thermal annealing
- 2014
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 115:24, s. 244304-
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Tidskriftsartikel (refereegranskat)abstract
- Superlattices containing 3 nm thick silicon rich silicon nitride sublayers and 3 nm and 10 nm thick SiO2 barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3 nm SiO2 barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.5-12.5 nm, which were randomly distributed within the structure. Although in the sample with 10 nm SiO2 barriers some fragments of the multilayer structure could be still observed after thermal annealing, nevertheless, the formation of large nanocrystals with diameters up to 10 nm was confirmed by dark field transmission electron microscopy. Thus, in contrast to the previously published results, the expected size control of silicon nanocrystals was lost. According to the FTIR results, the thermal annealing of SiNx/SiO2 superlattices led to the formation of silicon nanocrystals in mostly oxynitride matrix. Annealed samples demonstrated a photoluminescence peak at 885 nm related to the luminescence of silicon nanocrystals, as confirmed by time-resolved photoluminescence measurements. The loss of nanocrystals size control is discussed in terms of the migration of oxygen atoms from the SiO2 barriers into the silicon rich silicon nitride sublayers. A thermodynamic mechanism responsible for this process is proposed. According to this mechanism, the driving force for the oxygen migration is the gain in the configuration entropy related to the relative arrangements of oxygen and nitrogen atoms.
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| 6. |
- Zelenina, A., et al.
(författare)
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Structural and optical properties of size controlled Si nanocrystals in Si3N4 matrix : The nature of photoluminescence peak shift
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 114:18, s. 184311-
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Tidskriftsartikel (refereegranskat)abstract
- Superlattices of Si3N4 and Si-rich silicon nitride thin layers with varying thickness were prepared by plasma enhanced chemical vapor deposition. After high temperature annealing, Si nanocrystals were formed in the former Si-rich nitride layers. The control of the Si quantum dots size via the SiNx layer thickness was confirmed by transmission electron microscopy. The size of the nanocrystals was well in agreement with the former thickness of the respective Si-rich silicon nitride layers. In addition X-ray diffraction evidenced that the Si quantum dots are crystalline whereas the Si3N4 matrix remains amorphous even after annealing at 1200 degrees C. Despite the proven Si nanocrystals formation with controlled sizes, the photoluminescence was 2 orders of magnitude weaker than for Si nanocrystals in SiO2 matrix. Also, a systematic peak shift was not found. The SiNx/Si3N4 superlattices showed photoluminescence peak positions in the range of 540-660nm (2.3-1.9 eV), thus quite similar to the bulk Si3N4 film having peak position at 577nm (2.15 eV). These rather weak shifts and scattering around the position observed for stoichiometric Si3N4 are not in agreement with quantum confinement theory. Therefore theoretical calculations coupled with the experimental results of different barrier thicknesses were performed. As a result the commonly observed photoluminescence red shift, which was previously often attributed to quantum-confinement effect for silicon nanocrystals, was well described by the interference effect of Si3N4 surrounding matrix luminescence.
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| 7. |
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| 8. |
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| 9. |
- Estrader, Marta, et al.
(författare)
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Origin of the large dispersion of magnetic properties in nanostructured oxides : FexO/Fe3O4 nanoparticles as a case study
- 2015
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 7:7, s. 3002-3015
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Tidskriftsartikel (refereegranskat)abstract
- The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides.
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| 10. |
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| 11. |
- Spirkoska, D., et al.
(författare)
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Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures
- 2009
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 80:24
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Tidskriftsartikel (refereegranskat)abstract
- The structural and optical properties of three different kinds of GaAs nanowires with 100% zinc-blende structure and with an average of 30% and 70% wurtzite are presented. A variety of shorter and longer segments of zinc-blende or wurtzite crystal phases are observed by transmission electron microscopy in the nanowires. Sharp photoluminescence lines are observed with emission energies tuned from 1.515 eV down to 1.43 eV when the percentage of wurtzite is increased. The downward shift of the emission peaks can be understood by carrier confinement at the interfaces, in quantum wells and in random short period superlattices existent in these nanowires, assuming a staggered band offset between wurtzite and zinc-blende GaAs. The latter is confirmed also by time-resolved measurements. The extremely local nature of these optical transitions is evidenced also by cathodoluminescence measurements. Raman spectroscopy on single wires shows different strain conditions, depending on the wurtzite content which affects also the band alignments. Finally, the occurrence of the two crystallographic phases is discussed in thermodynamic terms.
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| 12. |
- Vilardell, Anna M., et al.
(författare)
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Dense nanostructured calcium phosphate coating on titanium by cold spray
- 2017
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Ingår i: Journal of the European Ceramic Society. - : Elsevier. - 0955-2219 .- 1873-619X. ; 37:4, s. 1747-1755
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Tidskriftsartikel (refereegranskat)abstract
- This article deals with the understanding of building-up mechanisms of bioactive nanocrystalline hydroxyapatite coatings by Cold Spray, revealing very promising results in contrast to more conventional techniques such as Plasma Spray. A full characterization of feedstock and coatings is provided. The agglomerated structure of the powder proved to be suitable to obtain successfully thick hydroxyapatite coatings. A crystallite size below similar to 20 nm in the powder and the as-sprayed coatings is calculated by the Rietveld X-ray refinement method and agreed by Transmission Electron Microscopy. Some wipe tests were carried out on Ti6Al4V substrates in order to study the deposition of single particles and the nanoscale features were evaluated. The resulting structure indicates that there is no delimitation of particle boundaries and the overall coating has been formed by effective compaction of the original nanocrystallites, leading to consistent and consolidated layers. (C) 2016 Elsevier Ltd. All rights reserved.
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| 13. |
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| 14. |
- Dash, Saroj Prasad, 1975, et al.
(författare)
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Spin precession and inverted Hanle effect in a semiconductor near a finite-roughness ferromagnetic interface
- 2011
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- Although the creation of spin polarization in various nonmagnetic media via electrical spin injection from a ferromagnetic tunnel contact has been demonstrated, much of the basic behavior is heavily debated. It is reported here that, for semiconductor/Al(2)O(3)/ferromagnet tunnel structures based on Si or GaAs, local magnetostatic fields arising from interface roughness dramatically alter and even dominate the accumulation and dynamics of spins in the semiconductor. Spin precession in inhomogeneous magnetic fields is shown to reduce the spin accumulation up to tenfold, and causes it to be inhomogeneous and noncollinear with the injector magnetization. The inverted Hanle effect serves as the experimental signature. This interaction needs to be taken into account in the analysis of experimental data, particularly in extracting the spin lifetime tau(s) and its variation with different parameters (temperature, doping concentration). It produces a broadening of the standard Hanle curve and thereby an apparent reduction of tau(s). For heavily doped n-type Si at room temperature it is shown that tau(s) is larger than previously determined, and a new lower bound of 0.29 ns is obtained. The results are expected to be general and to occur for spins near a magnetic interface not only in semiconductors but also in metals and organic and carbon-based materials including graphene, and in various spintronic device structures.
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| 15. |
- Estradé, S., et al.
(författare)
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Distinguishing the core from the shell in MnOx/MnOy and FeOx/MnOx core/shell nanoparticles through quantitative electron energy loss spectroscopy (EELS) analysis
- 2012
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 43:1, s. 30-36
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Forskningsöversikt (refereegranskat)abstract
- The structural and chemical characterization of inverted bi-magnetic MnOx(antiferromagnetic)/MnOy(ferrimagnetic) and FeOx(soft-ferrimagnetic)/MnOx(hard-ferrimagnetic) core/shell nanoparticles has been carried out by means of scanning transmission electron microscopy with electron energy loss spectroscopy analysis, (S)TEM-EELS. Quantitative EELS was applied to assess the local composition of the nanoparticles by evaluating the local Mn oxidation state based on the Mn L-3/L-2 peak intensity ratio and the Mn L-3 peak onset. The analysis allows to unambiguously distinguish the core from the shell and to determine the nature of the involved manganese oxides in both cases. The results evidence that the structure of the nanoparticles is, in fact, more complex than the one designed by the synthesis parameters.
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| 16. |
- Estrader, M., et al.
(författare)
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Robust antiferromagnetic coupling in hard-soft bi-magnetic core/shell nanoparticles
- 2013
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- The growing miniaturization demand of magnetic devices is fuelling the recent interest in bi-magnetic nanoparticles as ultimate small components. One of the main goals has been to reproduce practical magnetic properties observed so far in layered systems. In this context, although useful effects such as exchange bias or spring magnets have been demonstrated in core/shell nanoparticles, other interesting key properties for devices remain elusive. Here we show a robust antiferromagnetic (AFM) coupling in core/shell nanoparticles which, in turn, leads to the foremost elucidation of positive exchange bias in bi-magnetic hard-soft systems and the remarkable regulation of the resonance field and amplitude. The AFM coupling in iron oxide-manganese oxide based, soft/hard and hard/soft, core/shell nanoparticles is demonstrated by magnetometry, ferromagnetic resonance and X-ray magnetic circular dichroism. Monte Carlo simulations prove the consistency of the AFM coupling. This unique coupling could give rise to more advanced applications of bi-magnetic core/shell nanoparticles.
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| 17. |
- Hiller, D., et al.
(författare)
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Absence of quantum confinement effects in the photoluminescence of Si3N4-embedded Si nanocrystals
- 2014
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 115:20, s. 204301-
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Tidskriftsartikel (refereegranskat)abstract
- Superlattices of Si-rich silicon nitride and Si3N4 are prepared by plasma-enhanced chemical vapor deposition and, subsequently, annealed at 1150 degrees C to form size-controlled Si nanocrystals (Si NCs) embedded in amorphous Si3N4. Despite well defined structural properties, photoluminescence spectroscopy (PL) reveals inconsistencies with the typically applied model of quantum confined excitons in nitride-embedded Si NCs. Time-resolved PL measurements demonstrate 10(5) times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si3N4 reference sample exhibits a similar PL peak as the Si NC samples. The origin of this luminescence is discussed in detail on the basis of radiative defects and Si3N4 band tail states in combination with optical absorption measurements. The apparent absence of PL from the Si NCs is explained conclusively using electron spin resonance data from the Si/Si3N4 interface defect literature. In addition, the role of Si3N4 valence band tail states as potential hole traps is discussed. Most strikingly, the PL peak blueshift with decreasing NC size, which is often observed in literature and typically attributed to quantum confinement (QC), is identified as optical artifact by transfer matrix method simulations of the PL spectra. Finally, criteria for a critical examination of a potential QC-related origin of the PL from Si3N4-embedded Si NCs are suggested.
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| 18. |
- Isaksson, Kerstin, et al.
(författare)
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Mutuality and Reciprocity in the Psychological Contracts of Temporary and Permanent Workers
- 2010
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Ingår i: Employment Contracts, Psychological Contracts, and Employee Well-Being: An International Study. - : Oxford University Press. - 9780191715389 - 9780199542697
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- One of the distinctive features of this study is the opportunity to compare the responses of employers and employees. The aim of this chapter is to determine the level of agreement about the content and fulfilment of the psychological contract. A second aim is to determine whether higher levels of agreement are associated with more positive outcomes. The results reveal relatively modest levels of agreement about promises made, agreement being somewhat higher with respect to permanent rather than temporary workers. With respect to fulfilment of promises, there is a fair degree of reciprocity with both parties tending to report moderate fulfilment. Higher levels of agreement about promises made and fulfilled are not strongly associated with more positive outcomes; rather it is the measure of fairness that is more important in determining outcomes. This raises questions about the role of mutuality in the exchange at the heart of the psychological contract.
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| 19. |
- Krycka, Kathryn L., et al.
(författare)
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Resolving Material-Specific Structures within Fe3O4 vertical bar gamma-Mn2O3 Core vertical bar Shell Nanoparticles Using Anomalous Small-Angle X-ray Scattering
- 2013
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 7:2, s. 921-931
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Tidskriftsartikel (refereegranskat)abstract
- Here it is demonstrated that multiple-energy, anomalous small-angle X-ray scattering (ASAXS) provides significant enhancement in sensitivity to internal material boundaries of layered nanoparticles compared with the traditional modeling of a single scattering energy, even for cases in which high scattering contrast naturally exists. Specifically, the material-specific structure of monodispersed Fe3O4 vertical bar gamma-Mn2O3 core vertical bar shell nanoparticles is determined, and the contribution of each component to the total scattering profile is identified with unprecedented clarity. We show that Fe3O4 vertical bar gamma-Mn2O3 core vertical bar shell nanoparticles with a diameter of 8.2 +/- 0.2 nm consist of a core with a composition near Fe3O4 surrounded by a (MnxFe1-x)(3)O-4 shell with a graded composition, ranging from x approximate to 0.40 at the Inner shell toward x approximate to 0.46 at the surface. Evaluation of the scattering contribution arising from the interference between material-specific layers additionally reveals the presence of Fe3O4 cores without a coating shell. Finally, it is found that the material-specific scattering profile shapes and chemical compositions extracted by this method are independent of the original input chemical compositions used in the analysis, revealing multiple-energy ASAXS as a powerful tool for determining internal nanostructured morphology even if the exact composition of the individual layers is not known a priori.
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| 20. |
- Lopez-Ortega, A., et al.
(författare)
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Strongly exchange coupled inverse ferrimagnetic soft/hard, MnxFe3-xO4/FexMn3-xO4, core/shell heterostructured nanoparticles
- 2012
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 4:16, s. 5138-5147
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Tidskriftsartikel (refereegranskat)abstract
- Inverted soft/hard, in contrast to conventional hard/soft, bi-magnetic core/shell nanoparticles of MnxFe3-xO4/FexMn3-xO4 with two different core sizes (7.5 and 11.5 nm) and fixed shell thickness (similar to 0.6 nm) have been synthesized. The structural characterization suggests that the particles have an interface with a graded composition. The magnetic characterization confirms the inverted soft/hard structure and evidences a strong exchange coupling between the core and the shell. Moreover, larger soft core sizes exhibit smaller coercivities and loop shifts, but larger blocking temperatures, as expected from spring-magnet or graded anisotropy structures. The results indicate that, similar to thin film systems, the magnetic properties of soft/hard core/shell nanoparticles can be fine tuned to match specific applications.
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| 21. |
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| 22. |
- Torruella, Pau, et al.
(författare)
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3D Visualization of the Iron Oxidation State in FeO/Fe3O4 Core-Shell Nanocubes from Electron Energy Loss Tomography
- 2016
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 16:8, s. 5068-5073
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Tidskriftsartikel (refereegranskat)abstract
- The physicochemical properties used in numerous advanced nanostructured devices are directly controlled by the oxidation states of their constituents. In this work we combine electron energy-loss spectroscopy, blind source separation, and computed tomography to reconstruct in three dimensions the distribution of Fe2+ and Fe3+ ions in a FeO/Fe3O4 core/shell cube-shaped nanoparticle with nanometric resolution. The results highlight the sharpness of the interface between both oxides and provide an average shell thickness, core volume, and average cube edge length measurements in agreement with the magnetic characterization of the sample.
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| 23. |
- Vigliar, Elena, et al.
(författare)
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COVID-19 pandemic impact on cytopathology practice in the post-lockdown period: An international, multicenter study
- 2022
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Ingår i: Cancer Cytopathology. - : WILEY. - 1934-662X .- 1934-6638. ; 130:5, s. 344-351
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Tidskriftsartikel (refereegranskat)abstract
- Background In a previous worldwide survey, the authors showed a drastic reduction in the number of cytological specimens processed during the coronavirus disease 2019 "lockdown" period along with an increase in malignancy rates. To assess the continued impact of the pandemic on cytological practices around the world, they undertook a second follow-up worldwide survey collecting data from the post-lockdown period (2020). Methods Participants were asked to provide data regarding their cytopathology activity during the first 12 weeks of their respective national post-lockdown period (2020), which ranged from April 4 to October 31. Differences between the post-lockdown period and the corresponding 2019 period were evaluated, and the authors specifically focused on rates of malignant diagnoses. Results A total of 29 respondents from 17 countries worldwide joined the survey. Overall, a lower number of cytological specimens (n = 236,352) were processed in comparison with the same period in 2019 (n = 321,466) for a relative reduction of 26.5%. The overall malignancy rate showed a statistically significant increase (12,442 [5.26%] vs 12,882 [4.01%]; P < .001) during the same time period. Similar results were obtained if both malignancy and suspicious for malignancy rates were considered together (15,759 [6.58%] vs 16,011 [4.98%]; P < .001). Conclusions The data showed a persistent reduction in the cytological specimen volume during the post-lockdown period (2020). However, the relative increase in the cytological workload in the late part of the post-lockdown is a promising finding of a slow return to normality.
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| 24. |
- Vigliar, Elena, et al.
(författare)
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Global impact of the COVID-19 pandemic on cytopathology practice: Results from an international survey of laboratories in 23 countries
- 2020
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Ingår i: Cancer Cytopathology. - : WILEY. - 1934-662X .- 1934-6638. ; 128:12, s. 885-894
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Tidskriftsartikel (refereegranskat)abstract
- Background To the authors knowledge, the impact of the coronavirus disease 2019 (COVID-19) pandemic on cytopathology practices worldwide has not been investigated formally. In the current study, data from 41 respondents from 23 countries were reported. Methods Data regarding the activity of each cytopathology laboratory during 4 weeks of COVID-19 lockdown were collected and compared with those obtained during the corresponding period in 2019. The overall number and percentage of exfoliative and fine-needle aspiration cytology samples from each anatomic site were recorded. Differences in the malignancy and suspicious rates between the 2 periods were analyzed using a meta-analytical approach. Results Overall, the sample volume was lower compared with 2019 (104,319 samples vs 190,225 samples), with an average volume reduction of 45.3% (range, 0.1%-98.0%). The percentage of samples from the cervicovaginal tract, thyroid, and anorectal region was significantly reduced (P < .05). Conversely, the percentage of samples from the urinary tract, serous cavities, breast, lymph nodes, respiratory tract, salivary glands, central nervous system, gastrointestinal tract, pancreas, liver, and biliary tract increased (P < .05). An overall increase of 5.56% (95% CI, 3.77%-7.35%) in the malignancy rate in nongynecological samples during the COVID-19 pandemic was observed. When the suspicious category was included, the overall increase was 6.95% (95% CI, 4.63%-9.27%). Conclusions The COVID-19 pandemic resulted in a drastic reduction in the total number of cytology specimens regardless of anatomic site or specimen type. The rate of malignancy increased, reflecting the prioritization of patients with cancer who were considered to be at high risk. Prospective monitoring of the effect of delays in access to health services during the lockdown period is warranted.
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| 25. |
- Zuzak, Tycho J, et al.
(författare)
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Use of complementary and alternative medicine by children in Europe: Published data and expert perspectives
- 2013
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Ingår i: Complementary Therapies in Medicine. - : Elsevier. - 0965-2299 .- 1873-6963. ; 21, s. S34-S47
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Few data document the use of complementary and alternative medicine (CAM) in Europe, with even fewer investigating use by children. less thanbrgreater than less thanbrgreater thanMethods: A narrative, non-systematic review of CAM use in Europe was performed by combining data from published surveys with expert perspectives. Limitations created by a lack of representative studies, varying definitions of CAM use, and what qualifies as CAM in different countries was partially overcome by integrating local experts to summarise information available only in the national language and provide their perspectives about CAM availability, quality, use and popularity in their countries using a semi-structured questionnaire. Local and international published surveys were summarised, and the prevalence of CAM use was extrapolated. less thanbrgreater than less thanbrgreater thanResults: Data from 20 European countries were available, representing 69% of the European population. Some data about CAM use by the general population were available for 90% of the examined countries, whereas peer-reviewed published surveys were available for only 60%. We extrapolated that 56% (range: 10-90%, adjusted for population size) of the European population in general had used CAM at least once in the past year. Surveys in CAM use by children were available for 55% of the investigated countries. The extrapolated prevalence of CAM use by children in Europe was 52% (range: 5-90%, adjusted for population size). Paediatric CAM experts reported an increasing awareness for and use of CAM in healthcare institutions. less thanbrgreater than less thanbrgreater thanConclusion: This precursor for further surveys indicates that CAM appears to be popular not only among adults in Europe, but also for children. Development of a pan-European definition of CAM use and CAM therapies are required to achieve surveys comparable between European countries. Additionally, more research investigating the efficacy and potential adverse effects of CAM therapies is needed because of increasing CAM use by children in Europe.
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