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| 2. |
- Abelev, B., et al.
(författare)
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Two- and three-pion quantum statistics correlations in Pb-Pb collisions at root S-NN=2.76 TeV at the CERN Large Hadron Collider
- 2014
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:2
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Tidskriftsartikel (refereegranskat)abstract
- Correlations induced by quantum statistics are sensitive to the spatiotemporal extent as well as dynamics of particle-emitting sources in heavy-ion collisions. In addition, such correlations can be used to search for the presence of a coherent component of pion production. Two- and three-pion correlations of same and mixed charge are measured at low relative momentum to estimate the coherent fraction of charged pions in Pb-Pb collisions at root S-NN = 2.76 TeV at the CERN Large Hadron Collider with ALICE. The genuine three-pion quantum statistics correlation is found to be suppressed relative to the two-pion correlation based on the assumption of fully chaotic pion emission. The suppression is observed to decrease with triplet momentum. The observed suppression at low triplet momentum may correspond to a coherent fraction in charged-pion emission of 23% +/- 8%.
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| 3. |
- Agarwal, Prasoon, et al.
(författare)
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CGGBP1 mitigates cytosine methylation at repetitive DNA sequences
- 2015
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: CGGBP1 is a repetitive DNA-binding transcription regulator with target sites at CpG-rich sequences such as CGG repeats and Alu-SINEs and L1-LINEs. The role of CGGBP1 as a possible mediator of CpG methylation however remains unknown. At CpG-rich sequences cytosine methylation is a major mechanism of transcriptional repression. Concordantly, gene-rich regions typically carry lower levels of CpG methylation than the repetitive elements. It is well known that at interspersed repeats Alu-SINEs and L1-LINEs high levels of CpG methylation constitute a transcriptional silencing and retrotransposon inactivating mechanism. Results: Here, we have studied genome-wide CpG methylation with or without CGGBP1-depletion. By high throughput sequencing of bisulfite-treated genomic DNA we have identified CGGBP1 to be a negative regulator of CpG methylation at repetitive DNA sequences. In addition, we have studied CpG methylation alterations on Alu and L1 retrotransposons in CGGBP1-depleted cells using a novel bisulfite-treatment and high throughput sequencing approach. Conclusions: The results clearly show that CGGBP1 is a possible bidirectional regulator of CpG methylation at Alus, and acts as a repressor of methylation at L1 retrotransposons.
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| 4. |
- Albert, Ludvig, et al.
(författare)
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Icke-azeotropa blandningar i värmepumpar - Förstudie för fullskaleprojekt
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In cooperation between STAL Refrigeration AB and the Department of Heat and Power Technology, Chalmers University of Technology, an experimental heat pump with a nonazeotropic mixture as working fluid is being prepared. This will be the first full scale plant in Sweden.This report contains the results from a pre-study to thefull scale project. The influence of a non-azeotropic mixture, as compared with a pure fluid on the design of the components in the heat pump, has been analyzed. This study has partly been done with a previously developed computer program, which has been improved. Some supplementary routines have been added to it, and the specific design of the prepared experimental planthas been inserted.The experimental heat pump which is to be used, has a countercurrent evaporator and a crosscurrent condenser. Since the best design for a non-azeotropic mixture is countercurrent, heat exchanger calculations have been done for this type of condenser. Comparisons indicate that a shell and tube heat exchanger with the non-azeotropic mixture on the shell side is highly interesting to investigate practically. The study of the internal heat exchanger shows that the dependence of COP on the degree of superheat before the compressor is slightly larger for a non-azeotropic mixture than for a pure fluid.During this project and also afterwards a dynamic debate onthe environmental effect of "CFCs" has been going on. Theuse of the mixture HCFC22/CFCl14, suggested in this report,will be forbidden in the future. However, it is stillinteresting to study it, since there are more and betterthermodynamic and physical data available for this mixturethan for other non-azeotropic mixtures. The experience andknowledge acquired in this project are possible to apply onother mixtures. Accurate calculations can be done for thesewhen more reliable data are available.
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| 5. |
- Armerin, Fredrik, et al.
(författare)
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Valuing the housing cooperative conversion option
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Since the 1990s, both private and municipal owners of multifamily rentalproperties in Sweden have sold a large number of their properties to hous-ing cooperatives established by the property's tenants. One motivationfor the large increase in so called housing cooperative conversions is thatthe practice of rent regulation causes actual rents to be lower than market-clearing rent levels, especially in attractive areas in larger cities. By sell-ing the property to a housing cooperative, the property owner can takeadvantage of the positive price di®erence between the price of housing co-operative dwellings, which are determined by demand and supply, and thevalue of the property based on the assumption that the rents will continueto be lower than market rents.In this paper we use a real options approach to derive a closed-formvaluation formula for the option an owner of an income producing multi-family property has to sell it to a housing cooperative. In traditionaloption valuation models, the date when the option matures is known inadvance. However, it is common that the property owner does not knowin advance when the tenants (through the housing cooperative) will buythe property. In this paper we let the expected time to maturity, which isthe day when the tenants purchases the property from their landlord, tobe a random variable. The numerical examples suggest that the value ofthe conversion option increases as expected time to conversion increases,as well as when the volatility of the price of housing cooperative proper-ties increase. The real options approach suggested in this paper may beespecially useful to explicitly conceptualize the problem of valuing a rentalproperty with embedded options to switch it to another type of property.
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| 6. |
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| 7. |
- Hensen, P, et al.
(författare)
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Association scan of the novel psoriasis susceptibility region on chromosome 19 : evidence for both susceptible and protective loci
- 2003
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Ingår i: Experimental dermatology. - : John Wiley & Sons. - 0906-6705 .- 1600-0625. ; 12:4, s. 490-496
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Tidskriftsartikel (refereegranskat)abstract
- To follow up the novel psoriasis susceptibility region on chromosome 19 (PSORS6), we performed an association scan for psoriasis vulgaris using 45 evenly spaced DNA microsatellite markers. For this study, a new independent sample of 210 nuclear psoriasis families (trio design) from Northern Germany was recruited. We used the family based association test (FBAT) for an association scan over the chromosome 19 region encompassing 50.8 cM. We obtained a positive association for the markers D19S922 (allele 5, P = 0.008) and D19S916 (allele 13, P = 0.016), which correspond to the peak of the region identified in a previously performed scan. We identified two novel regions by a single marker, each showing negative association at D19S917 on 19p13.1 (allele 8, P = 0.0034) and at D19S425 (allele 9, P = 0.0005), compatible with the hypothesis of protective loci. These two novel regions were explored in more detail using novel microsatellite markers at an average distance of 100 kb. A separate analysis distinguishing between familial (n = 137) and sporadic (n = 73) psoriasis families showed that the familial trios contribute strongly in the region around D19S425 (P = 0.004), while the comparably small subset of 73 sporadic trios has a stronger effect at the locus around D19S917 (P = 0.026). These studies confirm the existence of a psoriasis susceptibility locus on chromosome 19 and give first evidence for the existence of both susceptible and protective loci in this region. Analysis of a dense marker set from these refined regions will eventually allow identification of the underlying susceptibility alleles.
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| 8. |
- Kabo, Elena, 1972, et al.
(författare)
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Assessing risks of subsurface initiated rolling contact fatigue from field measurements
- 2009
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Ingår i: Proceedings of the 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems. ; 1, s. 355-361
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Konferensbidrag (refereegranskat)abstract
- A previous simplification of the Dang Van equivalent stress measure for cases of wheel–rail contact is modified. The new criterion is suited for real-time rolling contact fatigue assessment of measured wheel–rail contact forces. The only parameters in the new expression for the equivalent stress are the vertical force and the wheel and rail radii.Comparisons between the new and the original criterion are carried out and show good agreement for the studied cases of tangent track operation. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Finally the influence of transient loads on the growth of RCF cracks in wheels was investigated. It was demonstrated that transients need to be spaced closer than roughly 10 meters to give any substantial increase in crack growth rates.
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| 9. |
- Köbke, S., et al.
(författare)
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Climate Overrides Effects of Fertilizer and Straw Management as Controls of Nitrous Oxide Emissions After Oilseed Rape Harvest
- 2022
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Oilseed rape (Brassica napus L.) is an important bioenergy crop that contributes to the diversification of renewable energy supply and mitigation of fossil fuel CO2 emissions. Typical oilseed rape crop management includes the use of nitrogen (N) fertilizer and the incorporation of oilseed rape straw into soil after harvest. However, both management options risk increasing soil emissions of nitrous oxide (N2O). The aim of this 2-years field experiment was to identify the regulating factors of N cycling with emphasis on N2O emissions during the post-harvest period. As well as the N2O emission rates, soil ammonia (NH4+) and nitrate (NO3−) contents, crop residue and seed yield were also measured. Treatments included variation of fertilizer (non-fertilized, 90 and 180kgNha−1) and residue management (straw remaining, straw removal). Measured N2O emission data showed large intra- and inter-annual variations ranging from 0.5 (No-fert + str) to 1.0kg N2O-N ha−1 (Fert-180 + str) in 2013 and from 4.1 (Fert-90 + str) to 7.3kg N2O-N ha−1 (No-fert + str) in 2014. Cumulative N2O emissions showed that straw incorporation led to no difference or slightly reduced N2O emissions compared with treatments with straw removal, while N fertilization has no effect on post-harvest N2O emissions. A process-based model, CoupModel, was used to explain the large annual variation of N2O after calibration with measured environmental data. Both modeled and measured data suggest that soil water-filled pore space and temperature were the key factors controlling post-harvest N2O emissions, even though the model seemed to show a higher N2O response to the N fertilizer levels than our measured data. We conclude that straw incorporation in oilseed rape cropping is environmentally beneficial for mitigating N2O losses. The revealed importance of climate in regulating the emissions implies the value of multi-year measurements. Future studies should focus on new management practices to mitigate detrimental effects caused by global warming, for example by using cover crops. Copyright © 2022 Köbke, He, Böldt, Wang, Senbayram and Dittert.
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| 10. |
- Lau, Buon Kiong, et al.
(författare)
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Antenna matching for performance optimization in compact MIMO systems
- 2007
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Ingår i: Microwave Exhibition and Workshop, 2007.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The implementation of MIMO technology on compact mobile terminal devices poses a unique challenge for system designers. This is because it requires that multiple antennas be closely separated in a confined volume, which results in strong mutual coupling among the antennas and high spatial correlation for the signals. In this paper, we present a review on the latest developments of using uncoupled impedance matching networks to counteract performance degradation due to the aforesaid effects. Then, we extend our previous study of utilizing identical uncoupled matching networks to optimize performance by allowing them to be different across the antennas. The numerical examples reveal that the enlarged optimization search space is effective in improving the received power and correlation, whereas only a modest gain in channel capacity is observed.
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