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- Gador, Niklas, et al.
(författare)
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Dynamical interference structures in fully coupled bound-bound state quantum wave-packet dynamics
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 70:3, s. 033418-
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Tidskriftsartikel (refereegranskat)abstract
- The quantum wave-packet dynamics in a bound-bound state system at intermediate coupling strength, the A and b states in the Rb-2 molecule coupled by spin-orbit interaction, was studied by ultrafast pump-probe molecular beam spectrocopy and quantum dynamical calculations. It was shown that even at elevated molecular temperatures the experimentally observed traces are characterized by dynamical interference structures of mesobatic, i.e., diabatic-adiabatic hybrid, kind. Two types of mesobatic motion were discerned: bistable, which occurs in both bound-unbound and bound-bound systems, and astable, which is particular to bound-bound systems at intermediate coupling strength. Contrary to previous expectations, the signatures of the quantum interference structures in pump-probe delay traces were found to be robust toward averaging over initial quantum states. It was shown that the spectral variations observed while tuning the pump pulse wavelength is a quantum matter-wave relative of the fringes observed in a pulsed optical Michelson interferometer.
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| 6. |
- Hamaguchi, Isao, et al.
(författare)
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Gene transfer improves erythroid development in ribosomal protein S19-deficient Diamond-Blackfan anemia.
- 2002
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Ingår i: Blood. - 1528-0020. ; 100:8, s. 2724-2731
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-Blackfan anemia (DBA) is a congenital bone marrow failure syndrome characterized by a specific deficiency in erythroid progenitors. Forty percent of the patients are blood transfusion-dependent. Recent reports show that the ribosomal protein S19 (RPS19) gene is mutated in 25% of all patients with DBA. We constructed oncoretroviral vectors containing the RPS19 gene to develop gene therapy for RPS19-deficient DBA. These vectors were used to introduce the RPS19 gene into CD34(+) bone marrow (BM) cells from 4 patients with DBA with RPS19 gene mutations. Overexpression of the RPS19 transgene increased the number of erythroid colonies by almost 3-fold. High expression levels of the RPS19 transgene improved erythroid colony-forming ability substantially whereas low expression levels had no effect. Overexpression of RPS19 had no detrimental effect on granulocyte-macrophage colony formation. Therefore, these findings suggest that gene therapy for RPS19-deficient patients with DBA using viral vectors that express the RPS19 gene is feasible. (Blood. 2002;100:2724-2731)
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- Irandoust, Manuchehr, 1953-, et al.
(författare)
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Impact of Preferences, Curricilum, and Learning Strategies on Academic Success
- 2002
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Ingår i: Education Economics. - : Taylor & Francis. - 0964-5292 .- 1469-5782. ; 10:1, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- This paper attempts to examine a few factors characterizing preferences, curriculum, and learning strategies that influence academic success and failure. On the basis of a proportional odds model, our findings reveal that good performance by the student depends on: (i) the time spent on physical training, (ii) the subjects chosen at high school, and (iii) the study of previously given examinations as a learning strategy. The results do not support the contention that the average score at high school, preparation by reading course literature prior to lectures, and time spent studying are important variables with regard to academic achievement. Our results suggest three policy implications: (i) to encourage students to engage in some kind of physical training, (ii) to guide students regarding how they should use the previously given examinations, and (iii) to require that students do course-work on the mathematics of economics.
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- Karlsson, David, et al.
(författare)
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Methodologies for model calibration to assist the design of a preparative ion-exchange step for antibody purification
- 2004
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1033:1, s. 71-82
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Tidskriftsartikel (refereegranskat)abstract
- This work proposes methodologies using a model-based approach to gain knowledge on and assist the development of an ion-exchange step in a protein purification process; the separation of IgG from a mixture containing IgG, insulin and transferrin. This approach is suitable for capture and intermediate steps in a process. Both methods involve four consecutive steps. Firstly, the retention of the different protein components is determined giving a retention map of the system. From this the optimal pH and buffer can be determined. Secondly, additional salt gradient experiments are performed at the selected pH. Thirdly, experimental breakthrough curves have to be generated for the protein if the adsorption capacity of the medium for each component is not known. Fourthly, a validation experiment is performed. In method 1, where the capacity for the medium is assumed to be known, the protein adsorption is described by Langmuir kinetics with a mobile phase modulator (MPM). In this description salt is considered to be inert. In method 2 the adsorption behavior is described by steric mass action (SMA), where the salt component competes with the proteins for the available binding sites. Both methods use a dispersion model to describe transport in the mobile phase in the column. The methods are able to predict the separation and loading behavior of the three components. The methods can, with reasonable accuracy, predict the breakthrough of transferrin in a mixture of insulin, IgG and transferrin. Method I requires fewer experiments and predicts the mean volume of breakthrough for the loading step in the validation experiment more accurately than method 2. On the other hand, method 2 has a better accuracy to predict the position of 10% breakthrough and the shape of the breakthrough curve. The methods suggested in this work are shown to be efficient in process development. Some additional experiments have to be performed to obtain the unknown parameters in the models. However, the predictability that is achieved results in less experimental work in the process design as a whole. (C) 2004 Elsevier B.V. All rights reserved.
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| 10. |
- Karlsson, David, et al.
(författare)
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Model-based optimization of a preparative ion-exchange step for antibody purification
- 2004
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1055:1-2, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- A method using a model-based approach to design and optimize an ion-exchange step in a protein purification process is proposed for the separation of IgG from a mixture containing IgG, BSA and myoglobin. The method consists of three steps. In the first step, the model is calibrated against carefully designed experiments. The chromatographic model describes the convective and dispersive flow in the column, the diffusion in the adsorbent particles, and the protein adsorption using Langmuir kinetics with mobile phase modulators (MPM). In the second step, the model is validated against a validation experiment and analyzed. In the third and final step, the operating conditions are optimized. In the optimization step, the loading volume and the elution gradient are optimized with regard to the most important costs: the fixed costs and the feed cost. The optimization is achieved by maximizing the objective functions productivity (i.e. the production rate for a given amount of stationary phase) and product yield (i.e. the fraction of IgG recovered in the product stream). All optimization is conducted under the constraint of 99% purity of the IgG. The model calibration and the analysis show that this purification step is determined mainly by the kinetics. although as large a protein as IgG is used in the study. The two different optima resulting from this study are a productivity of 2.7 g IgG/(s m(3)) stationary phase and a yield of 90%. This model-based approach also gives information of the robustness of the chosen operating conditions. It is shown that the bead diameter could only be increased from 15 mum to 35 mum with maximum productivity and a 99% purity constraint due to increased diffusion hindrance in larger beads. (C) 2004 Elsevier B.V. All rights reserved.
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| 11. |
- Karlsson, Niklas, 1967, et al.
(författare)
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The economics of meaning
- 2004
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Ingår i: Nordic Journal of Political Economy. ; :30, s. 61-75
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we draw attention to an important motive the desire for meaning that drive considerable human behavior and economic activity, but has been largely ignored by economists. We distinguish four interpretations of meaning that differ in the degree to which they are amenable to modeling using the standard economic tools of utility maximization. These four interpretations are, in decreasing order of their amenability to modeling in conventional terms: (1) meaning as a resolution of preferences; (2), meaning as an extension of oneself either socially or temporally; (3) meaning as an act of making sense of ones life; and (4) meaning as an assertion of free will. Drawing upon psychology and literature we analyze implications of these four interpretations of meaning for economics.
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- Knutsson, Anders, et al.
(författare)
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Shift workers' mortality scrutinized.
- 2004
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Ingår i: Chronobiol Int. - 0742-0528 .- 1525-6073. ; 21:6, s. 1049-53
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Tidskriftsartikel (refereegranskat)
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| 13. |
- Matsson, Hans, et al.
(författare)
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Targeted disruption of the ribosomal protein S19 gene is lethal prior to implantation.
- 2004
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Ingår i: Mol Cell Biol. - 0270-7306. ; 24:9, s. 4032-4037
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Tidskriftsartikel (refereegranskat)abstract
- The ribosomal protein S19 (RPS19) is located in the small (40S) subunit and is one of 79 ribosomal proteins. The gene encoding RPS19 is mutated in approximately 25% of patients with Diamond-Blackfan anemia, which is a rare congenital erythroblastopenia. Affected individuals present with decreased numbers or the absence of erythroid precursors in the bone marrow, and associated malformations of various organs are common. We produced C57BL/6J mice with a targeted disruption of murine Rps19 to study its role in erythropoiesis and development. Mice homozygous for the disrupted Rps19 were not identified as early as the blastocyst stage, indicating a lethal effect. In contrast, mice heterozygous for the disrupted Rps19 allele have normal growth and organ development, including that of the hematopoietic system. Our findings indicate that zygotes which are Rps19(-/-) do not form blastocysts, whereas one normal Rps19 allele in C57BL/6J mice is sufficient to maintain normal ribosomal and possibly extraribosomal functions.
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| 14. |
- Norgren, Niklas, et al.
(författare)
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Monoclonal antibodies selective for low molecular weight neurofilaments
- 2002
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Ingår i: Hybridoma and Hybridomics. - : Mary Ann Liebert Inc. - 1536-8599. ; 21:1, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- Neurofilaments are necessary for the maintenance of axonal caliber and structural organization of nerve cells. The low molecular weight form of neurofilament, the neurofilament light protein, which serves as the core of the filament, was used as immunogen for generation of hybridomas with selective reactivity with this form of the filament. Six hybridomas, out of approximately 100 tested clones, were highly discriminatory. All involved epitopes were localized to the rod region of the antigen, as determined by alpha-chymotrypsin digestion of the purified filament and enzymatic peptide mapping. Synthetic peptides (20 mers) covering the entire rod region did not react with the antibodies. A phage display peptide library was used to identify four consensus sequences for the antibodies. The results indicate that all epitopes were of conformational type. Pair-wise BIAcore data furthermore indicated that the epitopes were independent. The access to such specific reagents is a prerequisite for further elucidation of the biology of the low molecular weight form of neurofilaments proteins.
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| 15. |
- Widell, Niklas, et al.
(författare)
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Gateway-based call admission in distributed object oriented systems
- 2000
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Ingår i: Proceedings fifteenth Nordic Teletraffic Seminar, NTS-15, Lund University, August 22-24, 2000.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Many applications in telecommunications will depend on distributed systems to provide enough capacity. In a distributed system a service is split up into a number of modules (often called objects) that can be placed at different nodes or processors in a network. A service can be seen as a number of invocations of the objects in a certain order. There are a number of performance problems which have to be solved. How shall objects be distributed on the nodes? How shall the load be distributed among the nodes for a given object distribution? How shall the distributed system be protected from temporary overload situations? In our paper we investigate these questions for distributed systems where requests for service arrive to a gateway from which they distributed to the nodes of the system. We assume that the object distribution is given and we concentrate on protecting the system using three different external load control mechanisms: Percent Thinning, Call Gapping and Tokens. Using simulations, we nd that Tokens provide the best system protection.
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