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| 3. |
- de la Serna, Jorge Bernardino, et al.
(författare)
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Segregated Phases in Pulmonary Surfactant Membranes Do Not Show Coexistence of Lipid Populations with Differentiated Dynamic Properties
- 2009
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Ingår i: Biophysical Journal. - : Elsevier Inc. - 0006-3495. ; 97:5, s. 1381-1389
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Tidskriftsartikel (refereegranskat)abstract
- The composition of pulmonary surfactant membranes and films has evolved to support a complex lateral structure, including segregation of ordered/disordered phases maintained up to physiological temperatures. In this study, we have analyzed the temperature-dependent dynamic properties of native surfactant membranes and membranes reconstituted from two surfactant hydrophobic fractions (i.e., all the lipids plus the hydrophobic proteins SP-B and SP-C, or only the total lipid fraction). These preparations show micrometer-sized fluid ordered/disordered phase coexistence, associated with a broad endothermic transition ending close to 37°C. However, both types of membrane exhibit uniform lipid mobility when analyzed by electron paramagnetic resonance with different spin-labeled phospholipids. A similar feature is observed with pulse-field gradient NMR experiments on oriented membranes reconstituted from the two types of surfactant hydrophobic extract. These latter results suggest that lipid dynamics are similar in the coexisting fluid phases observed by fluorescence microscopy. Additionally, it is found that surfactant proteins significantly reduce the average intramolecular lipid mobility and translational diffusion of phospholipids in the membranes, and that removal of cholesterol has a profound impact on both the lateral structure and dynamics of surfactant lipid membranes. We believe that the particular lipid composition of surfactant imposes a highly dynamic framework on the membrane structure, as well as maintains a lateral organization that is poised at the edge of critical transitions occurring under physiological conditions.
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| 4. |
- Fouda, Adam, et al.
(författare)
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Influence of Selective Carbon 1s Excitation on Auger–Meitner Decay in the ESCA Molecule
- 2024
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Ingår i: Journal of Physical Chemistry Letters. - 1948-7185. ; 15:16, s. 4286-4293
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional spectral mapping is used to visualize how resonant Auger–Meitner spectra are influenced by the site of the initial core–electron excitation and the symmetry of the core-excited state in the trifluoroethyl acetate molecule (ESCA). We observe a significant enhancement of electron yield for excitation of the COO 1s → π* and CF3 1s → σ* resonances unlike excitation at resonances involving the CH3 and CH2 sites. The CF3 1s → π* and CF3 1s → σ* resonance spectra are very different from each other, with the latter populating most valence states equally. Two complementary electronic structure calculations for the photoelectron cross section and Auger–Meitner intensity are shown to effectively reproduce the site- and state-selective nature of the resonant enhancement features. The site of the core–electron excitation and the respective final state hole locality increase the sensistivity of the photoelectron signal at specific functional group sites. This showcases resonant Auger–Meitner decay as a potentially powerful tool for selectively probing structural changes at specific functional group sites of polyatomic molecules.
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| 5. |
- Isberg, Jan, et al.
(författare)
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Temperature dependence of hole drift mobility in high-purity single-crystal CVD diamond
- 2005
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Ingår i: Physica status solidi. A, Applied research. - : Wiley. - 0031-8965 .- 1521-396X. ; 202:11, s. 2194-2198
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Tidskriftsartikel (refereegranskat)abstract
- Hole transport properties in high-purity single crystal CVD diamond samples were studied using the time of flight technique with optical excitation of the carriers. The measurements were taken at different temperatures in the interval 80-470 K. By varying the intensity of the optical excitation over several orders of magnitude, measurements at different carrier concentrations have been performed. In this way, measurements have been made both in the space charge limited and non space charge limited regimes, with consistent results. The temperature dependence of the low-field hole drift mobility shows a 7(alpha) dependence with a approximate to -1.5, below 350 K. This indicates that acoustic phonon scattering is the dominant scattering mechanism and a very low concentration of ionized impurities in this material.
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| 6. |
- Jarvik, Gail P., et al.
(författare)
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Hemochromatosis risk genotype is not associated with colorectal cancer or age at its diagnosis
- 2020
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Ingår i: Human Genetics and Genomics Advances. - : Cell press. - 2666-2477. ; 1:1
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Tidskriftsartikel (refereegranskat)abstract
- Homozygotes for the higher penetrance hemochromatosis risk allele, HFE c.845G>A (p.Cys282Tyr, or C282Y), have been reported to be at a 2- to 3-fold increased risk for colorectal cancer (CRC). These results have been reported for small sample size studies with no information about age at diagnosis for CRC. An association with age at diagnosis might alter CRC screening recommendations. We analyzed two large European ancestry datasets to assess the association of HFE genotype with CRC risk and age at CRC diagnosis. The first dataset included 59,733 CRC or advanced adenoma cases and 72,351 controls from a CRC epidemiological study consortium. The second dataset included 13,564 self-reported CRC cases and 2,880,218 controls from the personal genetics company, 23andMe. No association of the common hereditary hemochromatosis (HH) risk genotype and CRC was found in either dataset. The odds ratios (ORs) for the association of CRC and HFE C282Y homozygosity were 1.08 (95% confidence interval [CI], 0.91–1.29; p = 0.4) and 1.01 (95% CI, 0.78–1.31, p = 0.9) in the two cohorts, respectively. Age at CRC diagnosis also did not differ by HFE C282Y/C282Y genotype in either dataset. These results indicate no increased CRC risk in individuals with HH genotypes and suggest that persons with HH risk genotypes can follow population screening recommendations for CRC.
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| 7. |
- Kolbeinsson, Ari, et al.
(författare)
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To What Extent is Gamification an Effective Tool for Onboarding Users into a DHM Tool
- 2021
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Ingår i: Design, User Experience, and Usability: UX Research and Design. - Cham : Springer. - 9783030782207 - 9783030782214 ; , s. 48-66
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Konferensbidrag (refereegranskat)abstract
- Applying game-like elements to tasks or computer systems meant for serious, non-game, activities is becoming more common, and is seen as a way to support users in learning a system or to support users in performing tasks better. Applying game-like elements requires an understanding of users, the target task, and what can motivate the target users in their tasks. As in any system development, the success of the design requires validating, and this may be done multiple times in the development cycle. Some concepts, such as usability or user experience have well-established testing methods, while gamification is still a relatively immature field and evaluation methods are still being developed. This paper follows the first evaluation of a gamification system to aid with onboarding new users into the IPS IMMA digital human modelling system, offering details on the heuristic evaluation method. So early in the process, it is inevitable that problems were found, largely to do with how the motivation of users was handled, and multiple suggestions for improvements are offered.
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| 9. |
- Lindblom, Adam, et al.
(författare)
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An inductive 700 MW high voltage pulse generator
- 2006
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Ingår i: IEEE Transactions on Plasma Science. - 0093-3813 .- 1939-9375. ; 34:5, s. 1838-1845
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Tidskriftsartikel (refereegranskat)abstract
- A repetitive inductive 700-MW high-voltage pulsegenerator that delivers a 150-ns square pulse with 20-ns rise timeat 150 kV has been constructed. The pulse generator has a 1:10 aircore transformer connected to a 25-Ω pulse forming line (PFL).The transformer and the PFL are both constructed using highvoltagecables. The closing switch of the PFL is a spark gap thatis in a water tank together with the cable endings of the PFL andtransformer. The electric field at the cable endings is refractivelygraded by the high permittivity of the surrounding water. ThePFL is charged in 2.5 μs to 170 kV, and the electric field in theclosing switch of the PFL reaches 33 kV/mm until the thresholdvoltage is exceeded. The efficiency of the pulse generator is 40%.The authors believe that this concept can be up-scaled to a 25-GWgenerator operating at 500 kV. An electric circuit simulation ofa 25-GW pulse generator and an electrostatic simulation for arefractive cable ending are presented.
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| 11. |
- Lindblom, Adam, et al.
(författare)
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High-voltage pulsed-power cable generator
- 2009
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Ingår i: IEEE Transactions on Plasma Science. - USA : IEEE. - 0093-3813 .- 1939-9375. ; 37:1, s. 236-242
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Tidskriftsartikel (refereegranskat)abstract
- A cable-based 25-GW pulsed-power generator with output impedance of 2 is presented. It is designed to deliver a 200-ns-long 500-kV pulse into a 10 load. The primary energy storage of the generator consists of a 50-kV 20-kJ capacitor bank. The 50-kV capacitor bank is discharged into a 1 : 12 transformer. The transformer is designed to charge a pulse-forming line (PFL) to 600 kV. When charged, the PFL is discharged into a load via a spark gap. The spark gap is located in a coaxial system containing deionized water together with the cable endings of the PFL and transformer. The electric field at the cable endings is refractively graded by the high permittivity of the surrounding water. The primary and secondary windings consist of high-voltage cables that are interleaved and wound together. The PFL consists of eight 40-m-long 110-kV coaxial cables with both ends connected to the load. Each cable screen is grounded in the middle and connected in parallel. The cables have a characteristic impedance of 30 . The parallel cable setup gives the PFL an impedance of 2 . The total length, height, and width of the pulse generator are 4, 2, and 1.2 m, respectively.
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| 14. |
- Lindblom, Adam, et al.
(författare)
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Inductive high voltage pulse generator based on resonance system
- 2007
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Ingår i: Journal of Electrical Engineering. - 1335-3632. ; 58:1, s. 19-25
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Tidskriftsartikel (refereegranskat)abstract
- A high voltage pulse generator based on inductive intermediate energy storage has been constructed. The current switching technique used in the generator is based on a resonance system. Opening switches for high currents are generally difficult to construct and the switch used here has proven to turn off 1.8 kA DC-current at a rate of 300 A/μs. The generator is equipped with a step-up transmission line transformer as intermediate magnetic energy storage and the primary and secondary energy storages are capacitive. An LC-resonance circuit is combined with 3 vacuum interrupters in series as an opening switch on the primary side of the transformer. Discharging the capacitor bank into the primary winding of the transformer introduces a 200 Hz sinusoidal oscillation on the primary current. The movable contacts in the vacuum interrupters are operated mechanically and stable arcs are formed as the gaps are opened. As the 200 Hz sinusoidal current reaches its first maximum, the small LC-resonance circuit is triggered and the current achieves a new frequency of 25 kHz. The large amplitude and high frequency generated by the LC-resonance circuit results in a zero crossing of the primary current. As the current crosses zero the arc deionises and the current is switched off. Pulse shaping with a 2 x 50 m Blumlein configuration on the secondary side of the transformer has been investigated. A rise-time of 40 ns and pulse duration of 700 ns were measured for a resistive load. The aim with this pulse generator is to get familiar with the challenges involved in scaling the system to higher performance.
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| 15. |
- Lindblom, Adam, 1973-
(författare)
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Inductive Pulse Generation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pulsed power generators are a key component in compact systems for generation of high-power microwaves (HPM). HPM generation by virtual cathode devices such as Vircators put high demands on the source. The rise time and the pulse length of the source voltage are two key issues in the generation of HPM radiation. This thesis describes the construction and tests of several inductive high power pulse generators. The pulse generators were designed with the intent to deliver a pulse with fast rise time and rectangular voltage. Therefore, the pulse generators are all based on discharges of transmission lines. The transmission lines used in the pulse generators are modern high voltage cables normally used in power transmission. All tested pulse generators have step up transformers as intermediate magnetic energy storage. Further, the pulse generators have contributed to the knowledge of compact designs. Closing switches is another important device in pulse generator architectures. In general, high power switching involving large currents and high voltages requires the use of robust switches. The switches used in the pulse generators of this thesis are of gas and liquid type.
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| 16. |
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| 17. |
- Nounu, Aayah, et al.
(författare)
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Salicylic Acid and Risk of Colorectal Cancer : A Two-Sample Mendelian Randomization Study
- 2021
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Ingår i: Nutrients. - : MDPI. - 2072-6643. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- Salicylic acid (SA) has observationally been shown to decrease colorectal cancer (CRC) risk. Aspirin (acetylsalicylic acid, that rapidly deacetylates to SA) is an effective primary and secondary chemopreventive agent. Through a Mendelian randomization (MR) approach, we aimed to address whether levels of SA affected CRC risk, stratifying by aspirin use. A two-sample MR analysis was performed using GWAS summary statistics of SA (INTERVAL and EPIC-Norfolk, N = 14,149) and CRC (CCFR, CORECT, GECCO and UK Biobank, 55,168 cases and 65,160 controls). The DACHS study (4410 cases and 3441 controls) was used for replication and stratification of aspirin-use. SNPs proxying SA were selected via three methods: (1) functional SNPs that influence the activity of aspirin-metabolising enzymes; (2) pathway SNPs present in enzymes' coding regions; and (3) genome-wide significant SNPs. We found no association between functional SNPs and SA levels. The pathway and genome-wide SNPs showed no association between SA and CRC risk (OR: 1.03, 95% CI: 0.84-1.27 and OR: 1.08, 95% CI: 0.86-1.34, respectively). Results remained unchanged upon aspirin use stratification. We found little evidence to suggest that an SD increase in genetically predicted SA protects against CRC risk in the general population and upon stratification by aspirin use.
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| 18. |
- Zeng, Chenjie, et al.
(författare)
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Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus
- 2016
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Ingår i: Breast Cancer Research. - : Springer Science and Business Media LLC. - 1465-5411 .- 1465-542X. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk. Method: We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more than 1300 imputed genetic variants in 48,155 cases and 43,612 controls of European descent, 6269 cases and 6624 controls of East Asian descent and 1116 cases and 932 controls of African descent in the Breast Cancer Association Consortium (BCAC; http://bcac.ccge.medschl.cam.ac.uk/), and in 15,252 BRCA1 mutation carriers in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Stepwise regression analyses were performed to identify independent association signals. Data from the Encyclopedia of DNA Elements project (ENCODE) and the Cancer Genome Atlas (TCGA) were used for functional annotation. Results: Analysis of data from European descendants found evidence for four independent association signals at 12p11, represented by rs7297051 (odds ratio (OR) = 1.09, 95 % confidence interval (CI) = 1.06-1.12; P = 3 x 10(-9)), rs805510 (OR = 1.08, 95 % CI = 1.04-1.12, P = 2 x 10(-5)), and rs1871152 (OR = 1.04, 95 % CI = 1.02-1.06; P = 2 x 10(-4)) identified in the general populations, and rs113824616 (P = 7 x 10(-5)) identified in the meta-analysis of BCAC ER-negative cases and BRCA1 mutation carriers. SNPs rs7297051, rs805510 and rs113824616 were also associated with breast cancer risk at P < 0.05 in East Asians, but none of the associations were statistically significant in African descendants. Multiple candidate functional variants are located in putative enhancer sequences. Chromatin interaction data suggested that PTHLH was the likely target gene of these enhancers. Of the six variants with the strongest evidence of potential functionality, rs11049453 was statistically significantly associated with the expression of PTHLH and its nearby gene CCDC91 at P < 0.05. Conclusion: This study identified four independent association signals at 12p11 and revealed potentially functional variants, providing additional insights into the underlying biological mechanism(s) for the association observed between variants at 12p11 and breast cancer risk.
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