Control of Spacecraft Formation with Disturbance Rejection and Exponential Gains

We address the problem of state feedback translational motion control of a spacecraft formation through a modified sliding surface controller using variable gains and I^2 action for disturbance rejection. The exponential varying gains ensure faster convergence of the state trajectories during attitude maneuver while keeping the gains small (and the system less stiff) for station keeping. Integral action is introduced for rejection of disturbances with a constant nonzero mean such as aerodynamic drag. A direct consequence is a drop in energy consumption when affected by sensor noise and a decrease in size of the error states residual when operating close to the equilibrium point. A large number of simulation results are presented to show the control performance

Strekkodeassistert legemiddeladministrering (SALA) i sykehus : Omfang og årsaker til handlinger som avviker fra prosedyrer for legemiddelhåndtering

Master's thesis in Health informatics (HSI500)Background Errors and nonconformities in drug administration cause many undesirable incidents in hospitals. Digital technology has a role in preventing drug errors. In 2017, the Health South-East introduced an electronic medical record (EMR) which supports physician order entry (CPOE), as well as facilitated barcode-assisted medication administration (BCMA) at a hospital in the region. The goal was to reduce drug errors through increased support in digital technology, such as scanning of single dose packed drugs and patient identification bracelets. The purpose of this master thesis was to survey experiences with the use of BCMA. Special emphasis was placed on the challenges of following a new digitized work process, as well as to survey the scope and causes of shortcuts and detours in drug administration. This is referred to in the literature as workarounds. Method Open observation of nurses, preparing and administering medications to hospital patients. The observation guide was based on the hospital's procedure in drug administration procedures. Focus group interview with nurses from four hospital departments. The interview guide was structured according to Steven Alter's work system framework. The focus group interview was recorded digitally, transcribed word for word, and analyzed using systematic text condensatio

Glycine and hyperammonemia : potential target for the treatment of hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric disorder caused by hepatic dysfunction. Numerous studies dictate that ammonia plays an important role in the pathogenesis of HE, and hyperammonemia can lead to alterations in amino acid homeostasis. Glutamine and glycine are both ammoniagenic amino acids that are increased in liver failure. Modulating the levels of glutamine and glycine has shown to reduce ammonia concentration in hyperammonemia. Ornithine Phenylacetate (OP) has consistently been shown to reduce arterial ammonia levels in liver failure by modulating glutamine levels. In addition to this, OP has also been found to modulate glycine concentration providing an additional ammonia removing effect. Data support that glycine also serves an important role in N-methyl D-aspartate (NMDA) receptor mediated neurotransmission in HE. This potential important role for glycine in the pathogenesis of HE merits further investigations

Neuropathological changes in the brain of pigs with acute liver failure

Abstract Objective. Cerebral edema is a serious complication of acute liver failure (ALF), which may lead to intracranial hypertension and death. An accepted tenet has been that the blood-brain barrier is intact and that brain edema is primarily caused by a cytotoxic etiology due to hyperammonemia. However, the neuropathological changes in ALF have been poorly studied. Using a well characterized porcine model we aimed to investigate ultrastructural changes in the brain from pigs suffering from ALF. Materials and methods. Sixteen female Norwegian Landrace pigs weighing 27-35 kg were randomised into two groups: ALF (n = 8) and sham operated controls (n = 8). ALF was induced with an end-to-side portacaval shunt followed by ligation of the hepatic arteries. Biopsies were harvested from three different areas of the brain (frontal lobe, cerebellum, and brain stem) following eight hours of ALF and analyzed using electron microscopy. Results. Profound perivascular and interstitial edema were found in all three areas. Disruption of pericytic and astrocytic processes were seen, reflecting breakdown/lesion of the blood-brain barrier in animals suffering from ALF. Furthermore, neurons and axons were edematous and surrounded by vesicles. Severe damage to Purkinje neuron (necrosis) and damaged myelin were seen in the cerebellum and brain stem, respectively. Biopsies from sham operated animals were normal. Conclusions. Our data support the concept that vasogenic brain edema plays an important role in the development of intracranial hypertension in pigs with ALF