Pediatri: sykepleie til barn og pårørende når det er barn som er innlagt på sykehus

Som sykepleier kan en møte barn mange steder, både i og utenfor sykehus. Sykepleie til barn er et sammensatt og utfordrende fagfelt, et hvert barn er unikt. Noen av elementene i denne oppgaven handler om utvikling- og tilknytningsteori, barns reaksjonsmønstre og mestringsevne under sykehusopphold og foreldrenes rolle. Resultatet fra denne studien viser at sykepleie til barn er komplekst, i tillegg til barnet så må en også ta hensyn til foreldrenes funksjon og behov. Sykepleie til barn er også for lite prioritert på skolen

Nonsequential Two-Photon Double Ionization of Atoms: Identifying the Mechanism

We develop an approximate model for the process of direct (nonsequential) two-photon double ionization of atoms. Employing the model, we calculate (generalized) total cross sections as well as energy-resolved differential cross sections of helium for photon energies ranging from 39 to 54 eV. A comparison with results of \textit{ab initio} calculations reveals that the agreement is at a quantitative level. We thus demonstrate that this complex ionization process is fully described by the simple model, providing insight into the underlying physical mechanism. Finally, we use the model to calculate generalized cross sections for the two-photon double ionization of neon in the nonsequential regime.Comment: 4 pages, 4 figure

Distinction between sequential and direct ionization in two-photon double ionization of helium

This paper aims to shed some light on the role of the direct, or nonsequential, ionization channel in the regime in which the sequential channel is open in two-photon double ionization (TPDI) of helium. In this regime the sequential channel dominates any direct contribution unless the laser pulse is of very short duration, in which case their distinction is hard to draw. Based on both a simple model and full solutions of the time-dependent Schrödinger equation, we aim to provide evidence of direct double ionization by identifying a term proportional to the pulse duration in the double ionization yield. Indeed, such a term is identified in the energy-differential yield. When it comes to the total double ionization probability, however, it turns out that the net first-order contribution is negative. The nature of the negative first-order contribution is discussed, and we argue that it is of correlated origin

Model Development and Investigations on Ion Homeostasis

The environment surrounding an organism, a cell and an organelle is constantly changing. To keep organisms functioning there is an everlasting need to regulate and adapt in order to keep the internal environment relatively constant. Homeostasis is the term used to describe this ability of a system to regulate and stabilize its environment. Different processes and compensatory mechanisms are employed to do this. Homeostasis is also the overall theme binding this thesis together, spanning from iron regulation in plants to the regulation of calcium (Ca2+) in humans. Ever since the term emerged, scientists have been searching for answers on how biological control mechanisms function and how they are able to maintain homeostasis. The work presented in this thesis is based on a computational approach using systems biology and control mechanisms like negative feedback and integral control. Controller motifs based on negative feedback loops between a controlled and manipulated/compensatory variable was previously identified by the research group, and has been used as a basis for the computational calculations and models. Plants need iron for their growth and development, and even though this essential nutrient is difficult to access through the soil due to its availability. In the soil iron is strongly bound as Fe2O3, and plants have developed different strategies for iron uptake. Iron is also of great importance for human nutrition. Iron deficiency is one of the major causes of anaemia. Anaemia is a world wide problem and is a condition with too few red bloods cells or where the haemoglobin level within these is lower than usual. Iron regulation and homeostasis was modeled for non-graminaceous plants, with Arabidopsis thaliana as a model species. Since iron is toxic for plants at high levels it needs to be under homeostatic control. A model in agreement with experimental observations was developed. Iron-dependent degradation of the high-affinity transporter IRT1 was included in agreement with experimental findings, as well as the importance of the transcription factor FIT for the regulation of cytosolic iron. Auxiliary feedback was also introduced and investigated in the model. The role of such feedback is to help improve adaptation kinetics without an influence to the set-point, resulting in a significant improvement of the system response time. Homeostasis was also explored in order to see whether oscillatory conditions, which are common in biological systems, could show robust homeostasis. Homeostatic oscillators were identified, where compensatory frequency or amplitude levels lead to the average level corresponding to the set-point. This indicates that even during sustained oscillatory conditions homeostasis can be observed, suggesting an extension of the concept. Frequency control with the frequency being homeostatically regulated have also been described by us. Cytosolic calcium (Ca2+) is a biological example of one of these conditions where oscillations, transients etc. take place even though Ca2+ is under strict homeostatic control. Dysregulation of cytosolic Ca2+ is critical as it will affect cellular signaling and promote apoptosis at high levels. A simple initial model of oscillating Ca2+ regulation was used as an example of oscillatory homeostats, which spiked the interest to investigate Ca2+ homeostasis on a cellular level. Thus started the approach on building a model on cytosolic Ca2+ homeostasis and regulatory mechanisms in non-excitable cells. The work was started from an initial simple model based on erythrocytes with few organelles by studying the inflow and outflow mechanisms through the plasma membrane. Hysteretic properties in the plasma membrane Ca2+ ATPase (PMCA) was studied and identified, and compared well with experimental results. We also suggest that the inflow of Ca2+ could be inhibited by carboxyeosin which was used as an inhibitor in experimental research based on model calculations fitting well with these. For the Ca2+ induced Ca2+ release mechanism through the inositol 1,4,5-trisphosphate receptor (IP3R) a dicalcic model has been presented. Comparing theoretical calculations with experimental bell-shaped curves of the Ca2+ dependency of the IP3R channel at different IP3 levels, a cooperativity of 2 has been suggested in the inhibition by Ca2+. Cooperativity in the capacitative Ca2+ entry was also investigated and compared to experiments. Finally, even though oscillations was not the focus of this latest project, the cellular model can show sustained Ca2+ oscillations with period length ranging from a few seconds up to 30 hours

A Schr\"{o}dinger equation for relativistic laser-matter interactions

A semi-relativistic formulation of light-matter interaction is derived using the so called propagation gauge and the relativistic mass shift. We show that relativistic effects induced by a super-intense laser field can, to a surprisingly large extent, be accounted for by the Schr{\"o}dinger equation, provided that we replace the rest mass in the propagation gauge Hamiltonian by the corresponding time-dependent field-dressed mass. The validity of the semi-relativistic approach is tested numerically on a hydrogen atom exposed to an intense XUV laser pulse strong enough to accelerate the electron towards relativistic velocities. It is found that while the results obtained from the ordinary (non-relativistic) Schr{\"o}dinger equation generally differ from those of the Dirac equation, merely demonstrating that relativistic effects are significant, the semi-relativistic formulation provides results in quantitative agreement with a fully relativistic treatment

Alternative gauge for the description of the light-matter interaction in a relativistic framework

We present a generalized velocity gauge form of the relativistic laser-matter interaction. In comparison with the (equivalent) regular minimal coupling description, this new form of the light-matter interaction results in superior convergence properties for the numerical solution of the time-dependent Dirac equation. This applies both to the numerical treatment and, more importantly, to the multipole expansion of the laser field. The advantages of the alternative gauge is demonstrated in hydrogen by studies of the dynamics following the impact of superintense laser pulses of extreme ultraviolet wavelengths and sub-femtosecond duration