Differences in mechanisms of modulation between rat liver cholesterol 7α-hydroxylase and HMG-CoA reductase

AbstractThe effects of microsomal HMG-CoA reductase kinase, cytosolic phosphoprotein phosphatase and cytosolic, thiol-dependent cholesterol 7α-hydroxylase stimulatory protein on purified cholesterol 7α-hydroxylase and HMG-CoA reductase from rat liver were compared. Neither HMG-CoA reductase kinase nor phosphoprotein phosphatase had any significant effect on cholesterol 7α-hydroxylase activity. They inhibited and stimulated, respectively, the activity of HMG-CoA reductase. The purified cytosolic protein which stimulated cholesterol 7α-hydroxylase threefold in the presence of glutathione had no effect on HMG-CoA reductase. The results show that there are separate intracellular systems for modulation of cholesterol 7α-hydroxylase and HMG-CoA reductase.Cholesterol 7α-hydroxylaseHMG-CoA reductaseKinasePhosphoprotein phosphataseGlutathion

Optimal H-infinity state feedback for systems with symmetric and Hurwitz state matrix

We address H-infinity state feedback and give a simple form for an optimal control law applicable to linear time invariant systems with symmetric and Hurwitz state matrix. More specifically, the control law as well as the minimal value of the norm can be expressed in the matrices of the system's state space representation, given separate cost on state and control input. Thus, the control law is transparent, easy to synthesize and scalable. If the plant possesses a compatible sparsity pattern, it is also distributed. Examples of such sparsity patterns are included. Furthermore, if the state matrix is diagonal and the control input matrix is a node-link incidence matrix, the open-loop system's property of internal positivity is preserved by the control law. Finally, we give an extension of the optimal control law that incorporate coordination among subsystems. Examples demonstrate the simplicity in synthesis and performance of the optimal control law

Conditions for political leadership in pluricentric Scandinavian regions

How does the increasingly pluricentric character of regional governance in Denmark, Sweden and Norway condition the political leadership of politicians elected at regional levels of government? In regional governance, politicians elected at different levels of governance compete for political leadership, and this competition is particularly intense in pluricentric regional governance arenas with a weak division of political power. In such cases, the political leadership capacity of elected politicians at regional levels of governance depends on their ability to attract regional followers and to mobilise the support and resources of strong, influential regional stakeholders. From an analysis of recent institutional reforms in the three Scandinavian countries and a literature review of the role played by politicians in regional governance in the wake of these reforms, the article concludes that Scandinavian regional governance is strongly pluricentric (with some variation), and that recent reforms have contributed to making it even more pluricentric in character.

H-infinity optimal control for infinite-dimensional systems with strictly negative generator

A simple form for the optimal H-infinity state feedback of linear time-invariant infinite-dimensional systems is derived. It is applicable to systems with bounded input and output operators and a closed, densely defined, self-adjoint and strictly negative state operator. However, unlike other state-space algorithms, the optimal control is calculated in one step. Furthermore, a closed-form expression for the L2-gain of the closed-loop system is obtained. The result is an extension of the finite-dimensional case, derived by the first two authors. Examples demonstrate the simplicity of synthesis as well as the performance of the control law

ICT and participation in school and outside school activities for children and youths with physical disabilities

The general aim was to investigate the use of Information and Communication Technology (ICT) and participation in computer activities in school and outside school among children and youth with physical disabilities (age 8-19 years), in comparison to children and youth in general. In particular the aim was to gain knowledge about the use of and satisfaction with computer-based assistive technology devices (ATDs) in school and outside school among children with physical disabilities. Study I investigated the use and non-use of ATDs in school by children with physical disabilities and described the children’s experiences of using these devices. Study II investigated the outside school activity patterns of children with physical disabilities, and specifically their ICT usage compared with non-disabled children. It also aimed to investigate the children’s opinions of computer use and the associations between their use of the Internet and their interaction with peers. Study III examined the prevalence of children with physical disabilities using a computer-based ATD, and investigated differences in the satisfaction of children and youths with disabilities who used or did not use computer-based ATDs in the application of computers for in school and outside school activities. Study IV determined the ICT use in school activities of two groups of children with physical disabilities comprising those who do and those who do not use a computer-based ATD, and compared them with children from the general population. In addition, positive factors associated with in-school computer use were identified for children with physical disabilities. The findings in Study I showed it is important that devices are integrated into educational practice and that children must experience the immediate benefits of ATD use for their function in everyday school activities without detrimental effects on their social participation if they are to use the devices provided. The latter was often more important than being able to perform activities independently. Study II showed two sets of activity patterns, depending on whether the child was disabled or not and on gender. Proportionally more children with physical disabilities were engaged in ICT-activities, while non-disabled children tended to be engaged in a broader range of activities outside school. The activity pattern was more uniform for boys and girls with disabilities than for their non-disabled peers. Use of the Internet was positively associated with peer interaction outside school. In Study III the prevalence of using computer-based ATDs was about 44% among children with physical disabilities, and many were dissatisfied with the service around their ATDs. These children were less satisfied with their computer use in education and outside school activities than the children who did not use an ATD. Study IV showed that children with physical disabilities used the computer for less varied educational activities than children in general. Attending mainstream school, the children’s age (notably, being 16-18 yrs old), their frequent computer usage, and the teachers’ frequent computer usage increased the participation of children with physical disabilities in computer-based activities. The findings of this thesis have contributed with new knowledge to participation, use of ICT and ATDs of children with physical disabilities in activities in school and outside school. In conclusion, the activity pattern outside school in children with physical disabilities is more varied than earlier research studying ICT-activities has shown. Digital skills (knowledge in using the computer and the Internet) developed outside school engage children with disabilities, giving them increased access to social interactions, and for educational purposes. Therefore, it is discouraging when schools do not provide children with disabilities with opportunities to fully exploit their digital skills in school, when these children participate in a less diverse range of computer activities in comparison with children in general. Children with physical disabilities are not always satisfied with their use of ATDs provided, and the choice to use or not to use an ATD is not only the child's decision. This is an ethical dilemma when children both use ATDs they do not want to use, but also do not use ATDs they want to use. Computer-based ATDs need to be highlighted as an intervention in participation in everyday activities for children with disabilities. However, those children are not satisfied with the use and service of their computer-based ATDs in and outside school. These results can be used as a basis for prioritising and developing support for the optimal use of ICT and ATDs in school and outside school of children with physical disabilities

Respiratory Component of the Orienting Reflex: A Novel Sensitive Index of Sensory-Induced Arousal in Rats

In humans, the integrated response to a novel stimulus (orienting reflex, OR) includes behavioral (head turning etc.) and well-characterized physiological components (changes in heart rate, respiration, skin conductance, and EEG patterns). In rodents, the physiological components of the OR include changes in heart rate and cutaneous vasoconstrictor tone, but respiratory changes have so far not been systematically documented. In the present study conducted in adult male Wistar rats, the OR was elicited by 60-dB acoustic tones while animals were in a whole-body plethysmograph for respiratory recordings. In addition to respiration, in different groups of animals we concurrently recorded either EEG, or heart rate (both by biotelemetry), or tail blood flow (using ultrasound Doppler). Acoustic stimuli provoked vigorous tachypneic responses with respiratory rate rising from 80–100 to 450–650 cpm, and with small and variable changes in tidal volume. This respiratory arousal response was often, but not always, accompanied by EEG desynchronization and by variable tail vasoconstriction, and by small and inconsistent changes in the heart rate. We conclude that tachypneic responses are a new highly sensitive index of sensory-induced arousal