| 1071. |
- Jackson, A D, et al.
(författare)
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Phase diagram of a rotating Bose-Einstein condensate with anharmonic confinement
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 69:5, s. 053619-
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Tidskriftsartikel (refereegranskat)abstract
- We examine the phase diagram of an effectively repulsive Bose-Einstein condensate of atoms that rotates in a quadratic-plus-quartic potential. With use of a variational method we identify the three possible phases of the system as a function of the rotational frequency of the trap and of the coupling constant. The derived phase diagram is shown to be universal and partly exact in the limit of weak interactions and small anharmonicity. The variational results are found to be consistent with numerical solutions of the Gross-Pitaevskii equation.
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| 1072. |
- Jackson, A D, et al.
(författare)
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Stability of the solutions of the Gross-Pitaevskii equation
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:5, s. 053617-
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Tidskriftsartikel (refereegranskat)abstract
- We examine the static and dynamic stability of the solutions of the Gross-Pitaevskii equation and demonstrate the intimate connection between them. All salient features related to dynamic stability are reflected systematically in static properties. We find, for example, the obvious result that static stability always implies dynamic stability and present a simple explanation of the fact that dynamic stability can exist even in the presence of static instability.
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| 1073. |
- Jacob, Merle, et al.
(författare)
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The persistence of big science and megascience in research and innovation policy
- 2012
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Ingår i: Science and Public Policy. - : Oxford University Press (OUP). - 0302-3427 .- 1471-5430. ; 39:4, s. 411-415
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Tidskriftsartikel (refereegranskat)abstract
- This special section of an issue of Science and Public Policy grew out of an interest in following the politics of the European Spallation Source (ESS) Facility at Lund, Sweden. The ESS spectacle provided a platform from which to review different research infrastructure projects and to place them in the context of science policy as a whole. Large-scale research infrastructure investments are often very visible and controversial science policy investments. This group of five papers provides insights into the persistence of these types of investments in an era where cost efficiency and the contribution of science to innovation and economic development appear to be the dominant rationale for investment.
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| 1074. |
- Jacobsson, T. Jesper, 1984-, et al.
(författare)
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2-Terminal CIGS-perovskite tandem cells : A layer by layer exploration
- 2020
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 207, s. 270-288
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the development of 2-terminal CIGS-perovskite tandem solar cells by exploring a range of stack sequences and synthetic procedures for depositing the associated layers. In the end, we converged at a stack sequence composed of SLG/Mo/CIGS/CdS/i-ZnO/ZnO:Al/NiO/PTAA/Perovskite/LiF/PCBM/SnO2/ITO. With this architecture, we reached performances only about 1% lower than the corresponding 4-terminal tandem cells, thus demonstrating functional interconnects between the two sub-cells while grown monolithically on top of each other. We go through the stack, layer-by-layer, discussing their deposition and the results, from which we can conclude what works, what does not work, and what potentially could work after additional modifications. The challenges for a successful 2-terminal tandem device include: how to deal with, or decrease, the surface roughness of the CIGS-stack, how to obtain uniform coverage of the layers between the CIGS and the perovskite while also obtaining a benign interface chemistry, and how to tune the band gaps of both the CIGS and the perovskite to obtain good optical matching. The investigation was based on CIGS with a power conversion efficiency around 14%, and perovskites with an efficiency around 12%, resulting in 2-terminal tandem cells with efficiencies of 15–16%. The results indicate that by using higher performing CIGS and perovskite sub-cells, it should be possible to manufacture highly efficient 2-terminal CIGS-perovskite tandem devices by using the protocols, principles, and procedures developed and discussed in this paper.
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| 1075. |
- Jacobsson, T. Jesper, 1984-, et al.
(författare)
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An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- 2022
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Ingår i: Nature Energy. - : Springer Nature. - 2058-7546. ; 7:1, s. 107-115
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Tidskriftsartikel (refereegranskat)abstract
- Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.
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| 1076. |
- Jadoon, Asim, et al.
(författare)
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Dynamic interaction of fixed dual spheres for several configurations and inflow conditions
- 2010
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Ingår i: European journal of mechanics. B, Fluids. - : Elsevier BV. - 0997-7546 .- 1873-7390. ; 29:1, s. 43-52
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Tidskriftsartikel (refereegranskat)abstract
- The changes in force characteristics as well as the shedding patterns for various dual sphere configurations are studied. The Reynolds numbers considered are 300, 600 and two different inflow conditions are used: steady and pulsating. The sphere formations are defined by the separation distance D-0 between the spheres and the angle between the line connecting the centres of the spheres and the main flow direction, gamma. The position of one of the spheres is varied in the range 0 degrees-90 degrees using a 15 degrees increment. Two separation distances are studied; 1.5D and 3D. The method used for the simulations is the Volume of Solid (VOS) approach, a method based on Volume of Fluid (VOF). A major conclusion from this work is that the sphere interaction alters the wake dynamics by obstructing the vortex shedding (generating a steady wake or a wake with lower Strouhal number) and by changing the direction of the lift force so that it in most cases is directed in the plane containing the sphere centres. The results also show that changing the inflow condition gives the same relative change in drag and lift as for a single sphere. The drag is substantially reduced by placing the sphere downstream in a tandem arrangement and slightly increased in a side-by-side arrangement. However, the effect is decreased by increasing separation distance and increasing Reynolds number.
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| 1077. |
- Jain, Saumey, et al.
(författare)
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On-Chip Neural Induction Boosts Neural Stem Cell Commitment : Toward a Pipeline for iPSC-Based Therapies
- 2024
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Ingår i: Advanced science (Weinheim, Baden-Wurttemberg, Germany). - : Wiley-VCH Verlagsgesellschaft. - 2198-3844.
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Tidskriftsartikel (refereegranskat)abstract
- The clinical translation of induced pluripotent stem cells (iPSCs) holds great potential for personalized therapeutics. However, one of the main obstacles is that the current workflow to generate iPSCs is expensive, time-consuming, and requires standardization. A simplified and cost-effective microfluidic approach is presented for reprogramming fibroblasts into iPSCs and their subsequent differentiation into neural stem cells (NSCs). This method exploits microphysiological technology, providing a 100-fold reduction in reagents for reprogramming and a ninefold reduction in number of input cells. The iPSCs generated from microfluidic reprogramming of fibroblasts show upregulation of pluripotency markers and downregulation of fibroblast markers, on par with those reprogrammed in standard well-conditions. The NSCs differentiated in microfluidic chips show upregulation of neuroectodermal markers (ZIC1, PAX6, SOX1), highlighting their propensity for nervous system development. Cells obtained on conventional well plates and microfluidic chips are compared for reprogramming and neural induction by bulk RNA sequencing. Pathway enrichment analysis of NSCs from chip showed neural stem cell development enrichment and boosted commitment to neural stem cell lineage in initial phases of neural induction, attributed to a confined environment in a microfluidic chip. This method provides a cost-effective pipeline to reprogram and differentiate iPSCs for therapeutics compliant with current good manufacturing practices.
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| 1078. |
- Jakobsson, Andreas, et al.
(författare)
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Computationally Efficient Time-Recursive IAA-Based Blood Velocity Estimation
- 2012
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Ingår i: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 60:7, s. 3853-3858
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution spectral Doppler is an important and powerful noninvasive tool for estimation of velocities in blood vessels using medical ultrasound scanners. Such estimates are typically formed using an averaged periodogram technique, resulting in well-known limitations in the resulting spectral resolution. Recently, we have proposed techniques to instead form high-resolution data-adaptive estimates exploiting measurements along both depth and emission. The resulting estimates gives noticeably superior velocity estimates as compared to the standard technique, but suffers from a high computational complexity, making it interesting to formulate computationally efficient implementations of the estimators. In this work, by exploiting the rich structure of the iterative adaptive approach (IAA) based estimator, we examine how these estimates can be efficiently implemented in a time-recursive manner using both exact and approximate formulations of the method. The resulting algorithms are shown to reduce the necessary computational load with several orders of magnitude without noticeable loss of performance.
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| 1079. |
- Jalilian, Ehsan, et al.
(författare)
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Luminescence properties of the Cu4I62- cluster
- 2011
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 13:14, s. 4729-4734
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Tidskriftsartikel (refereegranskat)abstract
- Two new solvates were prepared in the system Cu(I) I using a solvolysis reaction. The structures for both of them were solved by X-ray crystallography, showing that they constitute two modifications of the same compound with the net formula [Cu4I6](P(C6H5)(4))(2)center dot 2OC(CH3)(2). Both types of crystals show vivid fluorescence when exposed to UV light. The formation of the first modification (I) seems to be preferred by kinetics and on ageing in the mother liquor it converts to modification (II). The Cu positions in (I) are disordered while those in (II) are fully ordered. The luminescent properties of both crystals were characterized using a confocal microscope and an excitation wavelength of 405 nm, resulting in fluorescence spectra with the intensities of 1.22 and 0.52 relative to the reference (fluorescein 10 mu M). Density functional theory calculations on the ordered Cu4I62- core of modification (II) show that the de-excitation from LUMO to HOMO is responsible for the luminescence. The calculated emission spectrum has a maximum at 531 nm in good agreement with the results from confocal microscopy.
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| 1080. |
- Jansson, D. S., et al.
(författare)
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Brachyspira hyodysenteriae and other strongly beta-haemolytic and indole-positive spirochaetes isolated from mallards (Anas platyrhynchos)
- 2004
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 53:4, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the current study were to collect intestinal spirochaetes (genus Brachyspira) from farmed and wild mallards (Anas platyrhynchos) and to identify and classify those isolates that phenotypically resembled Brachyspira hyodysenteriae, an enteric pathogen of pigs. The isolation rate of Brachyspira spp. was high from both farmed (93%) and wild mallards (78%). In wild mallards, it appeared that Brachyspira spp. were more likely to be found in migratory birds (multivariate analysis: RR = 1(.)8, 95% Cl 1(.)1-3(.)1) than in mallards sampled in a public park. Pure cultures of putative B. hyodysenteriae were obtained from 22 birds. All five isolates from farmed mallards and ten randomly selected isolates with this phenotype were used for further studies. All isolates from farmed mallards and two of the isolates from wild mallards were PCR-positive for the tlyA gene of B. hyodysenteriae. Two isolates from farmed mallards were selected for pulsed field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) analysis. These isolates clustered with the type and reference strains of B. hyodysenteriae. 16S rDNA sequence analysis performed on 11 of the strains showed that they were all closely related to each other and to the B. hyodysenteriae-Brachyspira intermedia cluster. Three of the mallard isolates had 16S rDNA sequences that were identical to those of B. hyodysenteriae strains R1 and NIV-1 previously isolated from common rheas (Rhea americana). To conclude, the isolates from farmed mallards and two isolates from wild mallards were classified as B. hyodysenteriae based on the factthat they could not be differentiated by any of the applied methods from type, reference and field strains of B. hyodysenteriae. The remaining isolates could not be assigned irrefutably to any of the presently recognized Brachyspira species. These results point to a broader host spectrum of B. hyodysenteriae than is generally recognized, and to the presence in mallards of strongly haemolytic and indole-producing spirochaetes that possess many, but not all, of the currently recognized characteristics of B. hyodysenteriae.
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