| 1. |
|
|
| 2. |
- Dzhigaev, D., et al.
(författare)
-
Bragg coherent x-ray diffractive imaging of a single indium phosphide nanowire
- 2016
-
Ingår i: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 18:6
-
Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) Bragg coherent x-ray diffractive imaging (CXDI) with a nanofocused beam was applied to quantitatively map the internal strain field of a single indium phosphide nanowire. The quantitative values of the strain were obtained by pre-characterization of the beam profile with transmission ptychography on a test sample. Our measurements revealed the 3D strain distribution in a region of 150 nm below the catalyst Au particle. We observed a slight gradient of the strain in the range of 0.6% along the [111] growth direction of the nanowire. We also determined the spatial resolution in our measurements to be about 10 nm in the direction perpendicular to the facets of the nanowire. The CXDI measurements were compared with the finite element method simulations and show a good agreement with our experimental results. The proposed approach can become an effective tool for in operando studies of the nanowires.
|
|
| 3. |
- Göransson, D. J.O., et al.
(författare)
-
Coulomb blockade from the shell of an InP-InAs core-shell nanowire with a triangular cross section
- 2019
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 114:5
-
Tidskriftsartikel (refereegranskat)abstract
- We report on growth of InP-InAs core-shell nanowires and demonstration of the formation of single quantum structures, which show the Coulomb blockade effect, over entire lengths of the nanowires. The core-shell nanowires are grown by a selective area growth technique via metal-organic vapor phase epitaxy. The as-grown core-shell nanowires are found to be of wurtzite crystals. The InP cores have a hexagonal cross section, while the InAs shells are grown preferentially on specific { 1 1 ¯ 00} facets, leading to the formation of the core-shell nanowires with an overall triangular cross section. The grown core-shell nanowires are transferred onto a Si/SiO 2 substrate and then contacted by several narrow metal electrodes. Low-temperature transport measurements show the Coulomb-blockade effect. We analyze the measured gate capacitance and single electron charging energy of the devices and demonstrate that a quantum structure which shows the Coulomb blockade effect of a many-electron quantum dot is formed over the full length of a single core-shell nanowire and consists of the entire InAs shell in the nanowire.
|
|
| 4. |
- Mergenthaler, K., et al.
(författare)
-
Anti-Stokes photoluminescence probing k-conservation and thermalization of minority carriers in degenerately doped semiconductors
- 2017
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- It has recently been found that anti-Stokes photoluminescence can be observed in degenerately n-doped indium phosphide nanowires, when exciting directly into the electron gas. This anti-Stokes mechanism has not been observed before and allows the study of carrier relaxation and recombination using standard photoluminescence techniques. It is important to know if this anti-Stokes photoluminescence also occurs in bulk semiconductors as well as its relation to carrier recombination and relaxation. Here we show that similar anti-Stokes photoluminescence can indeed be observed in degenerately doped bulk indium phosphide and gallium arsenide and is caused by minority carriers scattering to high momenta by phonons. We find in addition that the radiative electron-hole recombination is highly momentum-conserving and that photogenerated minority carriers recombine before relaxing to the band edge at low temperatures. These observations challenge the use of models assuming thermalization of minority carriers in the analysis of highly doped devices.
|
|
| 5. |
|
|
| 6. |
- Borschel, Christian, et al.
(författare)
-
A New Route toward Semiconductor Nanospintronics : Highly Mn-Doped GaAs Nanowires Realized by Ion-Implantation under Dynamic Annealing Conditions
- 2011
-
Ingår i: Nano letters (Print). - Washington : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 11:9, s. 3935-3940
-
Tidskriftsartikel (refereegranskat)abstract
- We report on highly Mn-doped GaAs nanowires (NWs) of high crystalline quality fabricated by ion beam implantation, a technique that allows doping concentrations beyond the equilibrium solubility limit. We studied two approaches for the preparation of Mn-doped GaAs NWs: First, ion implantation at room temperature with subsequent annealing resulted in polycrystalline NWs and phase segregation of MnAs and GaAs. The second approach was ion implantation at elevated temperatures. In this case, the single-crystallinity of the GaAs NWs was maintained, and crystalline, highly Mn-doped GaAs NWs were obtained. The electrical resistance of such NWs dropped with increasing temperature (activation energy about 70 meV). Corresponding magnetoresistance measurements showed a decrease at low temperatures, indicating paramagnetism. Our findings suggest possibilities for future applications where dense arrays of GaMnAs nanowires may be used as a new kind of magnetic material system.
|
|
| 7. |
- Carlberg, Patrick, et al.
(författare)
-
Nanoimprint - a tool for realizing nano-bio research
- 2004
-
Ingår i: 2004 4th IEEE Conference on Nanotechnology. - 0780385365 ; , s. 199-200
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we present a status report on how implementation of nanoimprint lithography has advanced our research. Contact guidance nerve growth experiments have so far primarily been done on micrometer-structured surfaces. We have made a stamp with 17 areas of different, submicron, line width and spacing covering a total 2.6 mm
|
|
| 8. |
- Göransson, D. J.O., et al.
(författare)
-
Measurements of Strain and Bandgap of Coherently Epitaxially Grown Wurtzite InAsP-InP Core-Shell Nanowires
- 2019
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 19:4, s. 2674-2681
-
Tidskriftsartikel (refereegranskat)abstract
- We report on experimental determination of the strain and bandgap of InAsP in epitaxially grown InAsP-InP core-shell nanowires. The core-shell nanowires are grown via metal-organic vapor phase epitaxy. The as-grown nanowires are characterized by transmission electron microscopy, X-ray diffraction, micro-photoluminescence (μPL) spectroscopy, and micro-Raman (μ-Raman) spectroscopy measurements. We observe that the core-shell nanowires are of wurtzite (WZ) crystal phase and are coherently strained with the core and the shell having the same number of atomic planes in each nanowire. We determine the predominantly uniaxial strains formed in the core-shell nanowires along the nanowire growth axis and demonstrate that the strains can be described using an analytical expression. The bandgap energies in the strained WZ InAsP core materials are extracted from the μPL measurements of individual core-shell nanowires. The coherently strained core-shell nanowires demonstrated in this work offer the potentials for use in constructing novel optoelectronic devices and for development of piezoelectric photovoltaic devices.
|
|
| 9. |
|
|
| 10. |
- Jain, Vishal, 1989-, et al.
(författare)
-
Processing and Characterization of Nanowire Arrays for Photodetectors
- 2015
-
Ingår i: Nano-Structures for Optics and Photonics. - Dordrecht : Springer. - 9789401791427 - 9789401791328 - 9789401791335 ; , s. 511-512
-
Konferensbidrag (refereegranskat)abstract
- We present a fabrication scheme of contacting arrays of vertically standing nanowires (NW) for LEDs (Duan et al. Nature 409:66–69, 2001), photodetectors (Wang et al. Science (NY) 293:1455–1457, 2001) or solar cell applications (Wallentin et al. Science (NY) 339:1057–1060, 2013). Samples were prepared by depositing Au films using nano-imprint lithography (Må rtensson et al. Nano Lett 4:699–702, 2004) which are used as catalysts for NW growth in a low-pressure metal organic vapour phase epitaxy system where III-V precursors and dopant gases are flown at elevated temperatures which lead to the formation of NWs with different segments (Borgström et al. Nano Res 3:264–270, 2010). An insulating SiO2 layer is then deposited and etched from the top segments of the NWs followed by sputtering of a transparent top conducting oxide and opening up 1 × 1 mm2 device areas through a UV lithography step and etching of the top contact from non-device areas. A second UV lithography step was subsequently carried out to open up smaller windows on the ITO squares for bond pad definition, followed by metallization and lift-off; and the substrate is used as back contact. We also report on the electrical and optical properties of near-infrared p+−i−n+ photodetectors/solar cells based on square millimeter ensembles of InP nanowires grown on InP substrates. The study includes a sample series where the p +-segment length was varied between 0 and 250 nm, as well as solar cell samples with 9.3 % efficiency with similar design. The NWs have a complex modulated crystal structure of alternating wurtzite and zincblende segments, a polytypism that depends on dopant type. The electrical data for all samples display excellent rectifying behavior with an ideality factor of about 2 at 300 K. From spectrally resolved photocurrent measurements, we conclude that the photocurrent generation process depends strongly on the p +-segment length. Without p +-segment in the NWs, photogenerated carriers funneled from the substrate into the NWs contribute significantly to the photocurrent. Adding a p +-segment shifts the depletion region up into the i-region of the NWs reducing the substrate contribution to photocurrent while strongly improving the collections of carriers generated in the NWs, in agreement with theoretical modeling (Fig. 48.1). © Springer Science+Business Media Dordrecht 2015.
|
|
| 11. |
- Ouattara, Lassana, et al.
(författare)
-
Correlation lengths in stacked InAs quantum dot systems studied by cross-sectional scanning tunnelling microscopy
- 2007
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 18:14
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the influence of the InP spacer layer thickness on stacked InAs/InP quantum dots, using cross-sectional scanning tunnelling microscopy. We show that for a spacer layer thickness of up to 30 nm, the quantum dots are spatially correlated but for a separating distance of 50 nm the vertical ordering of the dots is lost. These values are the same as previously found for quantum dots in the InAs/GaAs system despite the large difference in lattice mismatch between the InAs/GaAs ( 7%) and InAs/InP ( 3%) systems. We show that the apparent similarities can be understood by a combination of intermixing in the dots and differences in dot size. Finally, we demonstrate that the size of the quantum dots is affected by their vertical correlation.
|
|
| 12. |
- Wolff, M., et al.
(författare)
-
Conceptualizing multidimensional barriers : a framework for assessing constraints in realizing recreational benefits of urban green spaces
- 2022
-
Ingår i: Ecology and Society. - : Resilience Alliance, Inc.. - 1708-3087. ; 27:2
-
Tidskriftsartikel (refereegranskat)abstract
- Although potential urban green space accessibility is being discussed widely, specific barriers that affect accessibility are often under-estimated. They do not equate to limited or uneven accessibility nor are they exclusively related to physical settings. Rather, the range of barriers and their complex interactions, including people’s perceptions, personal conditions, and institutional frameworks, make this topic less clear cut and difficult to put into practice for planning purposes. Given the importance of barriers when people make decisions, we present a conceptual framework to capture the cumulative and interactive effects of different barriers on realizing recreational benefits of urban green spaces. The framework classifies physical, personal, and institutional barriers and highlights their interactions based on three case studies: Stockholm, Leipzig, and Lodz. We argue that constraints to the accessibility of urban green spaces are not so much the interactions between various physical, personal, and institutional barriers, but more the significance that beneficiaries assign to them as perceived barrier effects. Studying barriers seeks to improve the knowledge about the non-use of urban green spaces and to enable us to draw conclusions about the actual accessibility of recreational benefits. Deduced from the conceptual framework, three pathways are contrasted for improving accessibility to the recreational benefits of urban green spaces: the environment, knowledge, and engagement. We argue that these pathways should not be a diffuse objective, but a sensitive and scale-dependent re-balance of individual, physical, and institutional factors for considering justice in environmental and green space planning and management. Our systematic conceptualization and classification of multidimensional barriers enables a more comprehensive understanding of individuals’ decisions in terms of accessing recreational benefits.
|
|
| 13. |
|
|
| 14. |
- Borgström, Anders, et al.
(författare)
-
Activation peptides in acute pancreatitis
- 1999
-
Ingår i: Acute Pancreatitis Novel Concepts in Biology and Therapy. - 3894123761 ; , s. 219-224
-
Bokkapitel (refereegranskat)
|
|
| 15. |
- Borgström, Magnus, et al.
(författare)
-
InAs quantum dots grown on InAlGaAs lattice matched to InP
- 2003
-
Ingår i: Journal of Crystal Growth. - 0022-0248. ; 252:4, s. 481-485
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present InAs quantum dots prepared on an InxAlyGa1-x-yAs surface by metal organic vapor phase epitaxy. Atomic force microscopy measurements indicate that dots grown on material with higher Al content are smaller, and that the local dot densities on step-bunched facets formed on the vicinal (0 0 1) surfaces increase. We find that these dots show luminescence at very long wavelengths, lambda(room temperature) approximate to 2.1 mum, and that the emission wavelengths are blue-shifted when the Al content is increased in the layer onto which dot material is deposited. (C) 2003 Elsevier Science B.V. All rights reserved.
|
|
| 16. |
- Borgström, Magnus, et al.
(författare)
-
Towards vertical III-V nanowire devices
- 2007
-
Ingår i: Proceedings of the 14th International Workshop on the Physics of Semiconductor Devices: IWPSD-2007. ; , s. 343-343
-
Konferensbidrag (refereegranskat)
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
- Espinet-Gonzalez, Pilar, et al.
(författare)
-
Radiation Tolerant Nanowire Array Solar Cells
- 2019
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 13:11, s. 12860-12869
-
Tidskriftsartikel (refereegranskat)abstract
- Space power systems require photovoltaics that are lightweight, efficient, reliable, and capable of operating for years or decades in space environment. Current solar panels use planar multijunction, III-V based solar cells with very high efficiency, but their specific power (power to weight ratio) is limited by the added mass of radiation shielding (e.g., coverglass) required to protect the cells from the high-energy particle radiation that occurs in space. Here, we demonstrate that III-V nanowire-array solar cells have dramatically superior radiation performance relative to planar solar cell designs and show this for multiple cell geometries and materials, including GaAs and InP. Nanowire cells exhibit damage thresholds ranging from ∼10-40 times higher than planar control solar cells when subjected to irradiation by 100-350 keV protons and 1 MeV electrons. Using Monte Carlo simulations, we show that this improvement is due in part to a reduction in the displacement density within the wires arising from their nanoscale dimensions. Radiation tolerance, combined with the efficient optical absorption and the improving performance of nanowire photovoltaics, indicates that nanowire arrays could provide a pathway to realize high-specific-power, substrate-free, III-V space solar cells with substantially reduced shielding requirements. More broadly, the exceptional reduction in radiation damage suggests that nanowire architectures may be useful in improving the radiation tolerance of other electronic and optoelectronic devices.
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
- Jacobsson, Daniel, et al.
(författare)
-
Particle-assisted GaxIn1-xP nanowire growth for designed bandgap structures
- 2012
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 23:24
-
Tidskriftsartikel (refereegranskat)abstract
- Non-tapered vertically straight GaxIn1-xP nanowires were grown in a compositional range from Ga0.2In0.8P to pure GaP in particle-assisted mode by controlling the trimethylindium, trimethylgallium and hydrogen chloride flows in metal-organic vapor phase epitaxy. X-ray energy dispersive spectroscopy in transmission electron microscopy revealed homogeneous radial material composition in single nanowires, whereas variations in the material composition were found along the nanowires. High-resolution x-ray diffraction indicates a variation of the material composition on the order of about 19% measuring an entire sample area, i.e., including edge effects during growth. The non-capped nanowires emit room temperature photoluminescence strongly in the energy range of 1.43-2.16 eV, correlated with the bandgap expected from the material composition.
|
|
| 28. |
- Kallesoe, Christian, et al.
(författare)
-
Integration, gap formation, and sharpening of III-V heterostructure nanowires by selective etching
- 2010
-
Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 28:1, s. 21-26
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial growth of heterostructure nanowires allows for the definition of narrow sections with specific semiconductor composition. The authors demonstrate how postgrowth engineering of III-V heterostructure nanowires using selective etching can form gaps, sharpening of tips, and thin sections simultaneously on multiple nanowires. They investigate the potential of combining nanostencil deposition of catalyst, epitaxial III-V heterostructure nanowire growth, and selective etching, as a road toward wafer scale integration and engineering of nanowires with existing silicon technology. Nanostencil lithography is used for deposition of catalyst particles on trench sidewalls and the lateral growth of III-V nanowires is achieved from such catalysts. The selectivity of a bromine-based etch on gallium arsenide segments in gallium phosphide nanowires is examined, using a hydrochloride etch to remove the III-V native oxides. Depending on the etching conditions, a variety of gap topologies and tiplike structures are observed, offering postgrowth engineering of material composition and morphology.
|
|
| 29. |
|
|
| 30. |
- Kriegner, D., et al.
(författare)
-
Structural investigation of GaInP nanowires using X-ray diffraction
- 2013
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 543, s. 100-105
-
Tidskriftsartikel (refereegranskat)abstract
- In this work the structure of ternary GaxIn1-xP nanowires is investigated with respect to the chemical composition and homogeneity. The nanowires were grown by metal-organic vapor-phase epitaxy. For the investigation of ensemble fluctuations on several lateral length scales, X-ray diffraction reciprocal space maps have been analyzed. The data reveal a complicated varying materials composition across the sample and in the nanowires on the order of 20%. The use of modern synchrotron sources, where beam-sizes in the order of several 10 mu m are available, enables us to investigate compositional gradients along the sample by recording diffraction patterns at different positions. In addition, compositional variations were found also within single nanowires in X-ray energy dispersive spectroscopy measurements. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 31. |
- Kudlicka, Jan
(författare)
-
Probabilistic Programming for Birth-Death Models of Evolution
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Phylogenetic birth-death models constitute a family of generative models of evolution. In these models an evolutionary process starts with a single species at a certain time in the past, and the speciations—splitting one species into two descendant species—and extinctions are modeled as events of non-homogenous Poisson processes. Different birth-death models admit different types of changes to the speciation and extinction rates.The result of an evolutionary process is a binary tree called a phylogenetic tree, or phylogeny, with the root representing the single species at the origin, internal nodes speciation events, and leaves currently living—extant—species (in the present time) and extinction events (in the past). Usually only a part of this tree, corresponding to the evolution of the extant species and their ancestors, is known via reconstruction from e.g. genomic sequences of these extant species.The task of our interest is to estimate the parameters of birth-death models given this reconstructed tree as the observation. While encoding the generative birth-death models as computer programs is easy and straightforward, developing and implementing bespoke inference algorithms are not. This complicates prototyping, development, and deployment of new birth-death models.Probabilistic programming is a new approach in which the generative models are encoded as computer programs in languages that include support for random variables, conditioning on the observed data, as well as automatic inference. This thesis is based on a collection of papers in which we demonstrate how to use probabilistic programming to solve the above-mentioned task of parameter inference in birth-death models. We show how these models can be implemented as simple programs in probabilistic programming languages. Our contribution also includes general improvements of the automatic inference methods.
|
|
| 32. |
|
|
| 33. |
- Mediavilla, I., et al.
(författare)
-
A cathodoluminescence study of InP/InGaP axially heterostructured NWs for tandem solar cells
- 2024
-
Ingår i: Nanotechnology. - 0957-4484. ; 35:19
-
Tidskriftsartikel (refereegranskat)abstract
- Axially heterostructured nanowires (NWs) constitute a promising platform for advanced electronic and optoelectronic nanodevices. The presence of different materials in these NWs introduces a mismatch resulting in complex strain distributions susceptible of changing the band gap and carrier mobility. The growth of these NWs presents challenges related to the reservoir effect in the catalysts droplet that affect to the junction abruptness, and the occurrence of undesired lateral growth creating core–shell heterostructures that introduce additional strain. We present herein a cathodoluminescence (CL) analysis on axially heterostructured InP/InGaP NWs with tandem solar cell structure. The CL is complemented with micro Raman, micro photoluminescence (PL), and high resolution transmission electron microscopy measurements. The results reveal the zinc blende structure of the NWs, the presence of a thin InGaP shell around the InP bottom cell, along with its associated strain, and the doping distribution.
|
|
| 34. |
- Mold, Jeff E., et al.
(författare)
-
Divergent clonal differentiation trajectories establish CD8(+) memory T cell heterogeneity during acute viral infections in humans
- 2021
-
Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 35:8
-
Tidskriftsartikel (refereegranskat)abstract
- The CD8(+) T cell response to an antigen is composed of many T cell clones with unique T cell receptors, together forming a heterogeneous repertoire of effector and memory cells. How individual T cell clones contribute to this heterogeneity throughout immune responses remains largely unknown. In this study, we longitudinally track human CD8(+) T cell clones expanding in response to yellow fever virus (YFV) vaccination at the single-cell level. We observed a drop in clonal diversity in blood from the acute to memory phase, suggesting that clonal selection shapes the circulating memory repertoire. Clones in the memory phase display biased differentiation trajectories along a gradient from stem cell to terminally differentiated effector memory fates. In secondary responses, YFV- and influenza-specific CD8(+) T cell clones are poised to recapitulate skewed differentiation trajectories. Collectively, we show that the sum of distinct clonal phenotypes results in the multifaceted human T cell response to acute viral infections.
|
|
| 35. |
- Muller, C. A., et al.
(författare)
-
Dexamethasone affects inflammation but not trypsinogen activation in experimental acute pancreatitis
- 2008
-
Ingår i: European Surgical Research. - : S. Karger AG. - 0014-312X .- 1421-9921. ; 40:4, s. 317-324
-
Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Trypsinogen activation and inflammation are early events in acute pancreatitis. This experimental study aimed to show the effects of dexamethasone on them. Methods: Cerulein and taurocholate pancreatitis were induced in 2 groups of 12 Wistar rats each. Six animals per group were injected with dexamethasone 1 h prior to the induction of acute pancreatitis. Amylase, phospholipase A2, TNF-alpha, IL-6, IL-10, alpha 2-antiplasmin in plasma and trypsinogen activation peptide (TAP) in urine were measured in healthy rats, then 0.5 and 6 h after pancreatitis induction. A severity score based on edema, necrosis and ascites was calculated at 6 h. TNF-alpha, IL-6 and IL-10 were measured 0.5 h after laparotomy in a control sham-operated group of 6 rats. Results: Inflammatory markers increased early in the course of both mild and severe acute pancreatitis and were significantly lowered by dexamethasone. The severity score was higher in taurocholate than in cerulein pancreatitis. It was significantly decreased by dexamethasone only in rats with mild pancreatitis. TAP remained unchanged in mild pancreatitis compared to healthy animals but increased late in the course of taurocholate pancreatitis. Trypsinogen activation was not affected by dexamethasone at all. Conclusion: Inflammation occurred earlier than the increase in urinary TAP in severe pancreatitis in rats. Dexamethasone inhibited inflammation but had no influence on TAP levels in experimental mild and severe acute pancreatitis. Copyright (C) 2008 S. Karger AG, Basel.
|
|
| 36. |
- Müller, C A, et al.
(författare)
-
Serum levels of procarboxypeptidase B and its activation peptide in patients with acute pancreatitis and non-pancreatic diseases
- 2002
-
Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 51:2, s. 229-235
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Carboxypeptidase B from the pancreatic gland may exist in three different molecular and immunoreactive forms: the proenzyme, the active enzyme, and the activation peptide. Aims: To investigate levels of procarboxypeptidase B (proCAPB) and its activation peptide in serum in acute pancreatitis to test the accuracy of these two variables as markers for the diagnosis of acute pancreatitis and for prediction of pancreatic necrosis. To elucidate whether leakage of proenzymes and activation of proenzymes reflect two different pathophysiological events in acute pancreatitis. Methods: Sera from patients with acute pancreatitis (n=85) and acute abdominal pain of non-pancreatic origin (n=53) were analysed for proCAPB and its activation peptide. Patients with pancreatitis were divided into necrotising (n=33) and oedematous attacks (n=52) using contrast enhanced computed tomography. Accuracy was determined using receiver operating characteristic curve analysis. Results: Immunoreactive carboxypeptidase B activation peptide (ir-CAPAP) concentration in serum on admission was 0.7 nmol/l (0-18.1) in patients with oedematous pancreatitis compared with 5.8 nmol/l (1.9-34) in patients with later development of pancreatic necrosis. Elevated levels of the activation peptide on admission correlated with an accuracy of 92% to later development of pancreatic necrosis. Ir-proCAPB concentration in serum on admission was 16.0 nmol/l (1.4-50.5) in all patients with acute pancreatitis versus 0.3 nmol/l (0-3.6) in patients with non-pancreatic acute abdominal disorders. Cases with oedematous pancreatitis had ir-proCAPB levels of 15.4 nmol/l (1.4-50.5) versus 19.1 nmol/l (2.7-36.1) in cases with later development of pancreatic necrosis. Measurement of the proenzyme can thus be useful for the diagnosis of acute pancreatitis (accuracy 99%) but levels did not correlate with later development of pancreatic necrosis (accuracy 56%). Conclusion: Leakage of proenzymes occurs in acute pancreatitis, irrespective of severity, while development of pancreatic necrosis occurs only when there is activation of the proenzymes.
|
|
| 37. |
- Paju, A, et al.
(författare)
-
Expression and characterization of trypsinogen produced in the human male genital tract
- 2000
-
Ingår i: American Journal of Pathology. - 1525-2191. ; 157:6, s. 2011-2021
-
Tidskriftsartikel (refereegranskat)abstract
- Trypsinogen is a serine proteinase produced mainly by the pancreas, but it has recently been found to be expressed also in several cancers such as ovarian and colon cancer and in vascular endothelial cells. In this study, we found that trypsinogen-1 and -2 are present at high concentrations (median levels, 0.4 and 0.5 mg/L, respectively) in human seminal fluid and purified them to homogeneity by immunoaffinity and anion exchange chromatography. Purified trypsinogen isoenzymes displayed a M(r) of 25 to 28 kd in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. Most of the trypsinogen-1 purified from seminal fluid was enzymatically active whereas trypsinogen-2 occurred as the proform, which could be activated by enteropeptidase in vitro. Immunohistochemically, trypsinogen protein was detected in the human prostate, urethra, utriculus, ejaculatory duct, seminal vesicles, deferent duct, epididymal glands, and testis. Expression of trypsinogen mRNA in the same organs was demonstrated by in situ hybridization. Trypsinogen mRNA was also detected in the prostate and seminal vesicles by reverse transcriptase-polymerase chain reaction and Northern blotting. Isolated trypsin was shown to activate the proenzyme form of prostate-specific antigen. These results suggest that trypsinogen isoenzymes found in seminal fluid are produced locally in the male genital tract and that they may play a physiological role in the semen.
|
|
| 38. |
- Rafael, Ehab, et al.
(författare)
-
Intramuscular autotransplantation of pancreatic islets in a 7-year-old child : a 2-year follow-up
- 2008
-
Ingår i: American Journal of Transplantation. - : Elsevier BV. - 1600-6135 .- 1600-6143. ; 8:2, s. 458-62
-
Tidskriftsartikel (refereegranskat)abstract
- A 7-year-old girl with severe hereditary pancreatitis underwent total pancreatectomy. A total of 160,000 islet equivalents (6400 islet/kg) were transplanted to the brachioradialis muscle of the right forearm. Her plasma C-peptide level was undetectable after pancreatectomy but increased to 1.37 ng/mL after 17 days; at this time point, her insulin requirement was 0.75 units of insulin/kg/day. At 5- and 27-months, her hemoglobin A1c (HbA1c) and insulin requirements were 4.5 and 5.3% and 0.3 and 0.18 units/kg/day, respectively. Basal and stimulated C-peptide levels were 0.67 +/- 0.07 and 3.36 +/- 1.37 ng/mL, respectively. Stimulated insulin levels were 30% higher in the islet-bearing arm compared to the contralateral arm after glucagon stimulation. After surgery and islet transplantation, the quality of life improved dramatically and she gained 8 kg of weight. In summary, a normal HbA1c, a low insulin requirement and the absence of recurrent hypoglycemia and the gradient of insulin between the arms indicate that the intramuscularly transplanted islets contribute to a long-term clinically significant metabolic control.
|
|
| 39. |
- Ronquist, Fredrik, et al.
(författare)
-
Universal probabilistic programming offers a powerful approach to statistical phylogenetics
- 2021
-
Ingår i: Communications Biology. - : Springer Nature. - 2399-3642. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- Statistical phylogenetic analysis currently relies on complex, dedicated software packages, making it difficult for evolutionary biologists to explore new models and inference strategies. Recent years have seen more generic solutions based on probabilistic graphical models, but this formalism can only partly express phylogenetic problems. Here, we show that universal probabilistic programming languages (PPLs) solve the expressivity problem, while still supporting automated generation of efficient inference algorithms. To prove the latter point, we develop automated generation of sequential Monte Carlo (SMC) algorithms for PPL descriptions of arbitrary biological diversification (birth-death) models. SMC is a new inference strategy for these problems, supporting both parameter inference and efficient estimation of Bayes factors that are used in model testing. We take advantage of this in automatically generating SMC algorithms for several recent diversification models that have been difficult or impossible to tackle previously. Finally, applying these algorithms to 40 bird phylogenies, we show that models with slowing diversification, constant turnover and many small shifts generally explain the data best. Our work opens up several related problem domains to PPL approaches, and shows that few hurdles remain before these techniques can be effectively applied to the full range of phylogenetic models.
|
|
| 40. |
- Sellberg, My M., 1987-
(författare)
-
Advancing Resilience Practice : Bridging social-ecological resilience theory and sustainable development practice
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis investigates the application of resilience thinking in different real-world settings and research-practice interfaces, for example in the context of natural resource management, local government planning and food systems. The number of cases of resilience practice are growing, including resilience assessments, planning and action, but there are still few scientific studies and even less synthesis across cases. This thesis describes existing cases of resilience practice, in natural resource management in Australia (Paper I) and across different international cases (Paper II), and experiments with new methods and approaches for improving resilience practice, based on pilot projects of co-production in Sweden (Paper III and Paper IV). The results confirm that resilience practice can contribute to the understanding and adaptive governance of complex social-ecological systems, but is weak in addressing the need for transformations, particularly for the sake of the resilience of Earth systems and global sustainability. The results also highlight practical strategies for engaging with complexity and novel approaches to enhance the potential of local-regional resilience practice to align with global sustainability concerns. The thesis as a whole sheds light on the field of resilience practice, by outlining different approaches, contexts and purposes and contributes to building transdisciplinary networks and relationships in multiple arenas.
|
|
| 41. |
- Sellberg, My M., et al.
(författare)
-
From resilience thinking to Resilience Planning : Lessons from practice
- 2018
-
Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 217, s. 906-918
-
Tidskriftsartikel (refereegranskat)abstract
- Resilience thinking has frequently been proposed as an alternative to conventional natural resource management, but there are few studies of its applications in real-world settings. To address this gap, we synthesized experiences from practitioners that have applied a resilience thinking approach to strategic planning, called Resilience Planning, in regional natural resource management organizations in Australia. This case represents one of the most extensive and long-term applications of resilience thinking in the world today. We conducted semi-structured interviews with Resilience Planning practitioners from nine organizations and reviewed strategic planning documents to investigate: 1) the key contributions of the approach to their existing strategic planning, and 2) what enabled and hindered the practitioners in applying and embedding the new approach in their organizations. Our results reveal that Resilience Planning contributed to developing a social-ecological systems perspective, more adaptive and collaborative approaches to planning, and that it clarified management goals of desirable resource conditions. Applying Resilience Planning required translating resilience thinking to practice in each unique circumstance, while simultaneously creating support among staff, and engaging external actors. Embedding Resilience Planning within organizations implied starting and maintaining longer-term change processes that required sustained multi-level organizational support. We conclude by identifying four lessons for successfully applying and embedding resilience practice in an organization: 1) to connect internal entrepreneurs to interpreters and networkers who work across organizations, 2) to assess the opportunity context for resilience practice, 3) to ensure that resilience practice is a learning process that engages internal and external actors, and 4) to develop reflective strategies for managing complexity and uncertainty.
|
|
| 42. |
- Sellberg, My M., et al.
(författare)
-
Improving participatory resilience assessment by cross-fertilizing the Resilience Alliance and Transition Movement approaches
- 2017
-
Ingår i: Ecology and Society. - 1708-3087. ; 22:1
-
Tidskriftsartikel (refereegranskat)abstract
- The concept of resilience is currently being widely promoted and applied by environmental and development organizations. However, their application of resilience often lacks theoretical backing and evaluation. This paper presents a novel cross-fertilization of two commonly used approaches for applying resilience thinking: the grassroots movement of Transition Towns and the Resilience Alliance's Resilience Assessment. We compared these approaches through a text analysis of their key handbooks and combined them in a series of participatory workshops with a local partner active in the Transition Movement. Our results demonstrate that despite sharing a number of key features, these two approaches have complementary strengths and weaknesses. Strengths of the Transition Movement include its motivating overarching narrative of the need to transform in response to global sustainability challenges, as well as practical tools promoting learning and participation. The Resilience Assessment's conceptual framework and structured process generated context-specific understanding of resilience, but provided little guidance on navigating transformation processes. Combining the Resilience Assessment's theory on complex systems with the Transition Movement's methods for learning also generated synergies in fostering complexity thinking. Based on these findings, we believe that integrating strengths from both approaches could be widely useful for practitioners seeking to apply resilience for sustainable development. Our study also highlights that methods for assessing resilience can be improved by combining insights from science and practice.
|
|
| 43. |
- Svensäter, Gunnel, et al.
(författare)
-
The acid-tolerant microbiota associated with plaque from initial caries and healthy tooth surfaces
- 2003
-
Ingår i: Caries Research. - : S. Karger AG. - 0008-6568 .- 1421-976X. ; 37:6, s. 395-403
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The intent of this study was to compare the inherent acid tolerance of bacteria in samples of dental plaque from tooth sites in subjects with and without initial caries. Plaque was collected from approximal surfaces showing early enamel caries and from healthy tooth surfaces in the same subjects, as well as from enamel surfaces of caries-free individuals. In addition to plating on blood agar, the plaque samples were plated directly on non-selective solid agar medium buffered to pH 7.0, 6.0, 5.5, 5.0, 4.5 and 4.0 to avoid any loss of adaptation to acid during primary isolation of plaque bacteria. The results showed that approximately 50% of the total cultivable plaque microbiota from caries, as well as healthy tooth sites, was able to grow at pH 5.5 and 1% at pH 5.0, pH values regarded as critical for the demineralization of tooth enamel. At pH 5.0, members of the genus Streptococcus were the dominant group, but mutans streptococci accounted for less than half of the streptococcal viable count. The other acid-tolerant streptococcal isolates included Streptococcus anginosus, Streptococcus constellatus, Streptococcus gordinii, Streptococcus intermedius, Streptococcus mitis, Streptococcus oralis, Streptococcus salivarius and SStreptococcus sanguis. Analysis of the results indicated that the mutans streptococci in dental plaque were highly variable with respect to acid tolerance, and that both caries and healthy sites harboured significant numbers of mutans streptococci that were not acid-tolerant.
|
|
| 44. |
|
|
| 45. |
- Wallentin, Jesper, et al.
(författare)
-
High-Performance Single Nanowire Tunnel Diodes.
- 2010
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:Online February 17, 2010, s. 974-979
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 27.6 at liquid helium temperature. These sub-100-nm-diameter structures are promising components for solar cells as well as electronic applications.
|
|
| 46. |
- Wallentin, Jesper, et al.
(författare)
-
Single GaInP nanowire p-i-n junctions near the direct to indirect bandgap crossover point
- 2012
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:25
-
Tidskriftsartikel (refereegranskat)abstract
- Axially defined GaInP single nanowire (NW) p-i-n junctions are demonstrated, with photocurrent response and yellow-green electroluminescence near the indirect bandgap crossover point at 2.18 eV (569 nm). We use DEZn and H2S as p- and n-type dopants, and find that they both affect the material composition and the crystal structure. The photovoltaic efficiency is comparable to single NW devices from binary III-V materials. These results demonstrate the potential of GaInP nanowires as a high-bandgap material for multijunction solar cells and light-emitting devices in the visible regime. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729929]
|
|
| 47. |
- Woksepp, Hanna, et al.
(författare)
-
High target attainment for beta-lactam antibiotics in intensive care unit patients when actual minimum inhibitory concentrations are applied
- 2017
-
Ingår i: European Journal of Clinical Microbiology and Infectious Diseases. - Heidelberg : Springer. - 0934-9723 .- 1435-4373. ; 36:3, s. 553-563
-
Tidskriftsartikel (refereegranskat)abstract
- Patients in the intensive care unit (ICU) are at risk for suboptimal levels of beta-lactam antibiotics, possibly leading to poor efficacy. Our aim was to investigate whether the actual minimum inhibitory concentration (MIC) compared to the more commonly used arbitrary epidemiological cut-off values (ECOFFs) would affect target attainment in ICU patients on empirical treatment with broad-spectrum beta-lactam antibiotics and to identify risk factors for not reaching target. In a prospective, multicenter study, ICU patients ae18 years old and treated with piperacillin/tazobactam, meropenem, or cefotaxime were included. Clinical and laboratory data were recorded. Serum trough antibiotic levels from three consecutive days were analyzed by liquid chromatography-mass spectrometry (LC-MS). The target was defined as the free trough concentration above the MIC (100% fT(> MIC)). MICECOFF was used as the target and, when available, the actual MIC (MICACTUAL) was applied. The median age of the patients was 70 years old, 52% (58/111) were males, and the median estimated glomerular filtration rate (eGFR) was 48.0 mL/min/1.73 m(2). The rate of patients reaching 100% fT > MICACTUAL was higher (89%, 31/35) compared to the same patients using MICECOFF (60%, p = 0.002). In total, 55% (61/111) reached 100% fT > MICECOFF. Increased renal clearance was independently associated to not reaching 100% fT > MICECOFF. On repeated sampling, > 77% of patients had stable serum drug levels around the MICECOFF. Serum concentrations of beta-lactam antibiotics vary extensively between ICU patients. The rate of patients not reaching target was markedly lower for the actual MIC than when the arbitrary MIC based on the ECOFF was used, which is important to consider in future studies.
|
|
| 48. |
- Zhao, Yongqian, et al.
(författare)
-
Probing strain in wurtzite InP-InAs core-shell nanowires with Raman spectroscopy
- 2021
-
Ingår i: Physical Review B. - 2469-9950. ; 104:23
-
Tidskriftsartikel (refereegranskat)abstract
- We used Raman spectroscopy to investigate phonon modes of single InP-InAs core-shell nanowire with a pure wurtzite phase to reveal the embedded strained state. Raman spectra show that the InP core exhibits tensile strain and the InAs shell exhibits compressive strain due to the radial heterostructure growth. Using different polarization excitation configurations, we identified distinct A1 (TO) and E1 (TO) modes, atomic vibrations along and perpendicular to the [0001] direction, respectively. We also identified E2h phonon modes in wurtzite InP and InAs, lattice vibration along with the [0001] direction, a fingerprint to distinguish a wurtzite phase from a zinc-blende phase. The Raman spectra changes reveal the resonance effects of InP and InAs between the E0+Δ0 energy level and the E1 gap by varying excitation energy, which indicates Γ7c-Γ6v transition consists of a split-off valence band and a band-gap transition along [0001] directions of the Brillouin zone. The polar patterns show the Raman A1 (TO) mode of InP only predominates in the x(yy)x¯ configuration, indicating the InP A1 (TO) phonon is sensitive to excitation polarization, suggesting the resonant Raman spectroscopy with specific polarization offers a direct way for characterizing wurtzite InP. Our findings deepen the understanding of strain in wurtzite-phase core-shell nanowire, providing a significant reference for engineering strain in core-shell nanowire to control optical and electric properties.
|
|
