Factors influencing flow of object focussed collaboration in collaborative virtual environments

Creativity is believed to be helped by an uncluttered state of mind known as flow and as the trend grows towards less immersive displays to produce an uncluttered workplace, we ask the question “Does immersion matter to the flow of distributed group work?”. The aim of this work is to study the impact of level of immersion on workflow and presence during object focussed distributed group work, and to discuss the relevance of these and other factors to supporting flow and creativity. This is approached through a comprehensive literature survey and significant new results. The study attempts to introduce a breadth of factors and relationships as opposed to proving a hypothesis and thus takes a wide qualitative rather than deep quantitative approach to testing and analysis.     

An operating system for a fault-tolerant multiprocessor controller

The development of an operating system that is a central component of a fault-tolerant multiprocessor is described. The operating system, while relatively simple and small, supports multitasking and multiprocessing, as well as both self-diagnostics and cross-diagnostics for fault detection. In the event of a fault, the system permits rapid reconfiguration in a manner that retains processing for the highest-priority tasks. Since the hardware needed to provide fault tolerance is available when there are no faults, the operating system can utilize this excess capacity to accomplish lower-priority tasks during normal operation. This approach yields graceful degradation in response to faults in the system components     

Measuring L-dopa in plasma and urine to monitor therapy of elderly patients with Parkinson disease treated with L-dopa and a dopa decarboxylase inhibitor

We have established a method for measuring L-dopa in plasma and urine, including the metabolites dopamine and L-dopac, using separation by ion-pair reversed-phase HPLC and quantification with an electrochemical detector. The assay was applied to the therapeutic monitoring of elderly patients with established Parkinson disease being treated with L-dopa plus a dopa decarboxylase inhibitor. Plasma L-dopa was evaluated in relation to dosage and postdose sampling time in 71 outpatients with Parkinson disease. L-Dopa concentrations were greatest in the patients taking the highest dosages prescribed and decreased significantly with increasing time after postdose sampling. Comparison of plasma L-dopa concentrations with a published therapeutic range established by intravenous administration of L-dopa was helpful in assessing the suitability of each patient's drug dosage, assessing patients' compliance, and avoiding overdosage but was not useful in the overall clinical assessment of progression of disease or of the long-term therapeutic response. Urine measurements confirmed the plasma concentrations but showed no further advantage. The recommended time for sample collection is between 1.5 and 3 h after the first morning dose. Plasma is the preferred matrix but if blood sampling is difficult, particularly from elderly/infirm individuals, an untimed urine collection could be used.     

Subcutaneous absorption kinetics and local tissue distribution of interferon and other solutes

The subcutaneous absorption and consequent tissue distribution of interferon g was studied in an anaesthetized rat model. Interferon g showed a biphasic disappearance profile from a solution in a subcutaneous absorption cell. Both the initial rapid distribution phase and slower removal phase followed first order kinetics. The steady-state clearance of interferon g from the cell was 1.41 +/- 0.38 x 10(-3) mL min-1, and the absorption half-life (t1/2) was 3.8 +/- 1.1 h (n = 4). Noradrenaline did not significantly alter either the clearance or absorption of interferon g (1.18 +/- 0.44 x 10(-3) mL min-1, P > 0.05, absorption t1/2 4.96 +/- 1.9 h, P > 0.05). Given that the clearance of smaller solutes, such as tritiated water, is significantly reduced when noradrenaline is coadministered, it is suggested that interferon g is removed via the lymphatic system rather than by the local blood supply. The amount of interferon g recovered in the plasma, urine and muscle is minimal relative to other solutes where the recovery is almost complete.     

Role of postural status in the nocturnal hemodynamic patterns of nonhuman primates

We compared the nocturnal hemodynamic patterns of seven tethered monkeys (Macaca mulatta) with those of seven chaired animals to determine whether the overnight changes are comparable in the two conditions. In both groups, we found a consistent hemodynamic pattern characterized by an overnight fall in cardiac output and central venous pressure and a rise in total peripheral resistance that maintained blood pressure homeostasis. The pattern of overnight change occurred despite major differences in response levels: cardiac output and central venous pressure were significantly elevated, and total peripheral resistance was significantly reduced at all times (from 1800 to 1200 h the following day) in the chaired animals relative to the tethered animals. This difference was probably due to an expanded plasma volume in the chaired animals, because stroke volume was also significantly elevated. Because the nocturnal hemodynamic pattern occurred under both conditions, it is likely that it is a stable biologic effect, which is probably related to an overnight loss in fluid volume that is not replaced in animals that sleep throughout the night.     

Linkage analysis in familial Alzheimer disease: description of the Duke and Boston data sets

Familial Alzheimer diseases is a neurological disorder of adult onset. Three research centers have each contributed their families and genetic linkage data for combined analyses. The data from the Duke and Boston centers, comprising 73 pedigrees for whom numerous markers on chromosomes 19 and 21 were typed are described.