| 1. |
- Yohannes, Elizabeth, et al.
(författare)
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Isotope signatures in winter moulted feathers predict malaria prevalence in a breeding avian host
- 2008
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 158:2, s. 299-306
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Tidskriftsartikel (refereegranskat)abstract
- It is widely accepted that animal distribution and migration strategy might have co-evolved in relation to selection pressures exerted by parasites. Here, we first determined the prevalence and types of malaria blood parasites in a breeding population of great reed warblers Acrocephalus arundinaceus using PCR. Secondly, we tested for differences in individual feather stable isotope signatures (delta C-13, delta N-15, delta D and delta S-34) to investigate whether malaria infected and non-infected birds had occupied different areas in winter. We show that birds moulting in Afro-tropical habitats with significantly higher delta C-13 and delta N-15 but lower delta D and delta S-34 values were more frequently infected with malaria parasites. Based on established patterns of isotopic distributions, our results indicate that moulting sites with higher incidence of malaria are generally drier and situated further to the north in West Africa than sites with lower incidence of malaria. Our findings are pertinent to the general hypothesis that animal distribution and particularly avian migration strategy might evolve in response to selection pressures exerted by parasites at different geographic scales. Tradeoffs between investment in energy demanding life history traits (e.g. migration and winter moult) and immune function are suggested to contribute to the particular choice of habitat during migration and at wintering sites.
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| 2. |
- Karhumaa, Kaisa, et al.
(författare)
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Comparison of xylose fermentation by Saccharomyces cerevisiae strains carrying either xylose reductase and xylitol dehydrogenase or xylose isomerase
- 2007
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Two heterologous pathways have been used to construct recombinant xylose-fermenting Saccharomyces cerevisiae strains: i) the xylose reductase ( XR) and xylitol dehydrogenase (XDH) pathway and ii) the xylose isomerase (XI) pathway. In the present study, the Pichia stipitis XR-XDH pathway and the Piromyces XI pathway were compared in an isogenic strain background, using a laboratory host strain with genetic modifications known to improve xylose fermentation (overexpressed xylulokinase, overexpressed non-oxidative pentose phosphate pathway and deletion of the aldose reductase gene GRE3). The two isogenic strains and the industrial xylose-fermenting strain TMB 3400 were studied regarding their xylose fermentation capacity in defined mineral medium and in undetoxified lignocellulosic hydrolysate. Results: In defined mineral medium, the xylose consumption rate, the specific ethanol productivity, and the final ethanol concentration were significantly higher in the XR- and XDH-carrying strain, whereas the highest ethanol yield was achieved with the strain carrying XI. While the laboratory strains only fermented a minor fraction of glucose in the undetoxified lignocellulose hydrolysate, the industrial strain TMB 3400 fermented nearly all the sugar available. Xylitol was formed by the XR-XDH-carrying strains only in mineral medium, whereas in lignocellulose hydrolysate no xylitol formation was detected. Conclusion: Despite by-product formation, the XR-XDH xylose utilization pathway resulted in faster ethanol production than using the best presently reported XI pathway in the strain background investigated. The need for robust industrial yeast strains for fermentation of undetoxified spruce hydrolysates was also confirmed.
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| 3. |
- Ojo, Olorunfemi, et al.
(författare)
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Welcome From: Technical Program Chairs
- 2023
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Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)
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| 4. |
- Cho, Jeong-woo, 1978-, et al.
(författare)
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On the Validity of the Fixed Point Equation and Decoupling Assumption for Analyzing the 802.11 MAC Protocol
- 2010
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Ingår i: Performance Evaluation Review. - : Association for Computing Machinery (ACM). - 0163-5999 .- 1557-9484. ; 38:2, s. 36-38
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Tidskriftsartikel (refereegranskat)abstract
- Performance evaluation of the 802.11 MAC protocol is classically based on the decoupling assumption, which hypothesizes that the backoff processes at different nodes are independent. A necessary condition for the validity of this approach is the existence and uniqueness of a solution to a fixed point equation. However, it was also recently pointed out that this condition is not sufficient; in contrast, a necessary and sufficient condition is a global stability property of the associated ordinary differential equation. Such a property was established only for a specific case, namely for a homogeneous system (all nodes have the same parameters) and when the number of backoff stages is either 1 or infinite and with other restrictive conditions. In this paper, we give a simple condition that establishes the validity of the decoupling assumption for the homogeneous case. We also discuss the heterogeneous and the differentiated service cases and show that the uniqueness condition is not sufficient; we exhibit one case where the fixed point equation has a unique solution but the decoupling assumption is not valid
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| 5. |
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| 6. |
- Kim, Anna, 1989, et al.
(författare)
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Open-volume microfluidic device for manipulation and monitoring of single-cells and tissues
- 2014
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Ingår i: Biosensors, 27-30 May 2014, Melbourne, Australia.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have previously reported a microfluidic pipette, which combines hydrodynamic flow confinement with solution switching for localized stimulation of single-cells and tissue slices. Some integration challenges still remain, pertaining to size and material properties. Here we present a novel pipette tip fabricated from the photo-polymer SU-8, for which a convenient process was developed, further expanding this technology for single-cell analysis.SU-8 micropipettes were patterned using standard photolithographic techniques and bonded using elevated temperature and high pressure. The fabrication procedure utilizes thermal release tape as a sacrificial layer facilitating release of the microstructures.The micropipettes were tested to withstand pressures between -0.6 and 0.95 bar, while featuring a tip width of only 200 μm. This new micropipette minimizes shadowing in experiments utilising tissue and offers different material composition for single-cell microscopy. The micropipettes have been designed for use in neuropharmacology, cardiac muscle research and for collection of biological substances from single-cells. The high chemical stability of the micropipettes will also allow application in surface chemistry research, for surface patterning with biomarkers and for guided cell growth. We aim to combine this device with THz impedance spectroscopy for monitoring physiological changes in single-cells. We present the first prototype of a millimetre wave coplanar waveguide (CPW), developed with ANSYS HFSS and to be used in combination with the device for single-cell impedance spectroscopy analysis. The CPW will be deposited on an independent glass substrate, separating the cell by a passivation layer. The cells will be exposed to various stimuli using the micropipette. The field of single-cell impedance spectroscopy analysis is at an early exploratory stage, and the combination of microfluidics with THz technology has the potential to bridge the gap between life science and engineering communities.
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| 7. |
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| 8. |
- Lee, Sang Hoon, 1982-, et al.
(författare)
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Critical behavior of the Ising model in annealed scale-free networks
- 2009
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 80:051127
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Tidskriftsartikel (refereegranskat)abstract
- We study the critical behavior of the Ising model in annealed scale-free (SF) networks of finite system size with forced upper cutoff in degree. By mapping the model onto the weighted fully connected Ising model, we derive analytic results for the finite-size scaling (FSS) near the phase transition, characterized by the cutoff-dependent two-parameter scaling with four distinct scaling regimes, in highly heterogeneous networks. These results are essentially the same as those found for the nonequilibrium contact process in annealed SF networks, except for an additional complication due to the trivial critical point shift in finite systems. The discrepancy of the FSS theories between annealed and quenched SF networks still remains in the equilibrium Ising model, like some other nonequilibrium models. All of our analytic results are confirmed reasonably well by numerical simulations.
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| 9. |
- Straszer, Boglárka, fil.dr, professor, 1973-
(författare)
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Perspektiv på modersmål
- 2022
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Ingår i: Lingua. - : Språklärarnas riksförbund. - 0023-6330. ; :4, s. 13-16
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Box, Marcus, 1972-, et al.
(författare)
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Bankruptcies in Sweden, 1774–1849 : Causes and structural differences
- 2020. - 1
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Ingår i: Luxury, Fashion and the Early Modern Idea of Credit. - London : Routledge. - 9780367332693 - 9780429318979 ; , s. 62-75
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Bokkapitel (refereegranskat)abstract
- In 1771, the first Swedish academic thesis on bankruptcy and insolvency was defended by Carl Bergström at Uppsala University. In this and other contemporary Swedish publications on the topic, shortcomings in the debtor’s character including gambling, dishonesty, fraudulent behaviour and a disposition for speculation were mentioned as major causes for bankruptcies. The idea that a debtor also was a swindler, and should be severely punished, was spread by Italian merchants to, above all, France, Spain, England and Germany. The moralising causal explanation for bankruptcy can be questioned from a social science research perspective. Based on modern literature, we can see many reasons for why a trader, shopkeeper or an artisan had to file for bankruptcy. An economic shock is an event that occurs outside of an economy and produces significant change within an economy.
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