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- Yoon, Y. J., et al.
(författare)
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Effect of p-type buffer layer on the properties of GaMnAs ferromagnetic semiconductors
- 2004
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Ingår i: Journal of the Korean Physical Society. - 0374-4884 .- 1976-8524. ; 45:SUPPL., s. S720-S723
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the magnetic and transport properties of Ga 1-xMn xAs epilayers grown either on undoped or on p-type doped GaAs buffer layer. The temperature dependence of the resistivity at zero magnetic field reveals that the Curie temperature (T C) in the Ga 1-xMn xAs layer grown on p-type doped GaAs buffer is slightly higher than that observed in the layer grown on undoped GaAs buffer. The magnetic and transport properties of the two samples show significant differences when they are placed in a magnetic field. In SQUID measurements, the Ga 1-xMn xAs layer grown on p-type buffer shows a larger coercive field and much slower decay of remanent magnetization than the layer grown on undoped buffer. This robust magnetic behavior observed in the doped sample is discussed in terms of the increase of free carrier concentration in the system arising from p-type doping in the buffer layer.
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| 2. |
- Ronis, MJJ, et al.
(författare)
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Alcoholic liver disease in rats fed ethanol as part of oral or intragastric low-carbohydrate liquid diets
- 2004
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Ingår i: Experimental biology and medicine (Maywood, N.J.). - : SAGE Publications. - 1535-3702 .- 1535-3699. ; 229:4, s. 351-360
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Tidskriftsartikel (refereegranskat)abstract
- The intragastric administration of ethanol as part of a lowcarbohydrate diet results in alcohol hepatotoxicity. We aimed to investigate whether comparable liver injury can be achieved by oral diet intake. Male Sprague-Dawley rats were fed ethanol as part of low-carbohydrate diets for 36–42 days either intragastrically or orally. Liver pathology, blood ethanol concentration, serum alanine amino transferase (ALT), endotoxin level, hepatic CYP2E1 induction, and cytokine profiles were assessed. Both oral and intragastric low-carbohydrate ethanol diets resulted in marked steatosis with additional inflammation and necrosis accompanied by significantly increased serum ALT, high levels of CYP2E1 expression, and production of auto-antibodies against malondialdehyde and hydroxyethyl free radical protein adducts. However, cytokine profiles differed substantially between the groups, with significantly lower mRNA expression of the anti-inflammatory cytokine interleukin 4 observed in rats fed low-carbohydrate diets orally. Inflammation and necrosis were significantly greater in rats receiving low-carbohydrate alcohol diets intragastrically than orally. This was associated with a significant increase in liver tumor necrosis factor α and interleukin 1β gene expression in the intragastric model. Thus, oral low-carbohydrate diets produce more ethanol-induced liver pathology than oral high-carbohydrate diets, but hepatotoxicity is more severe when a low-carbohydrate diet plus ethanol is infused intragastrically and is accompanied by significant increases in levels of proinflammatory cytokines.
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| 8. |
- Holme, Petter, et al.
(författare)
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Attack vulnerability of complex networks
- 2002
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 65:5, s. 056109-
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Tidskriftsartikel (refereegranskat)abstract
- We study the response of complex networks subject to attacks on vertices and edges. Several existing complex network models as well as real-world networks of scientific collaborations and Internet traffic are numerically investigated, and the network performance is quantitatively measured by the average inverse geodesic length and the size of the largest connected subgraph. For each case of attacks on vertices and edges, four different attacking strategies are used: removals by the descending order of the degree and the betweenness centrality, calculated for either the initial network or the current network during the removal procedure. It is found that the removals by the recalculated degrees and betweenness centralities are often more harmful than the attack strategies based on the initial network, suggesting that the network structure changes as important vertices or edges are removed. Furthermore, the correlation between the betweenness centrality and the degree in complex networks is studied.
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