The effect of bandwidth on telerobot system performance

The purpose of the experiment was to determine the effect that various slave-joint bandwidths have on telerobot system performance. The telerobot system consisted of a slave arm controlled by a master. The slave incorporated an impedance loop to provide local compliance in addition to the compliance provided by the operator via force feedback. Three joint bandwidths, 0.5, 1.0, and 2.0 Hz, were used. The performance measures were the task completion time and the sums of the squared forces and moments exerted on the environment. The task consisted of peg-in-hole insertion and removal. The results of the experiment indicate a significant performance decrease at 0.5-Hz bandwidth relative to the 1- and 2-Hz bandwidths. There was no significant change in performance between the 1- and 2-Hz bandwidths

Robust tuning of robot control systems

The computed torque control problem is examined for a robot arm with flexible, geared, joint drive systems which are typical in many industrial robots. The standard computed torque algorithm is not directly applicable to this class of manipulators because of the dynamics introduced by the joint drive system. The proposed approach to computed torque control combines a computed torque algorithm with torque controller at each joint. Three such control schemes are proposed. The first scheme uses the joint torque control system currently implemented on the robot arm and a novel form of the computed torque algorithm. The other two use the standard computed torque algorithm and a novel model following torque control system based on model following techniques. Standard tasks and performance indices are used to evaluate the performance of the controllers. Both numerical simulations and experiments are used in evaluation. The study shows that all three proposed systems lead to improved tracking performance over a conventional PD controller

Burden and outcome of HIV infection and other morbidities in health care workers attending an Occupational Health Program at the Provincial Hospital of Tete, Mozambique.

Objectives  To investigate the burden and outcome of HIV infection and other morbidities amongst a Mozambican hospital staff. Methods  Within an occupational health service set up in April 2008 in the provincial hospital of Tete, Mozambique, we offered to all staff members an initial clinical, laboratory and radiological screening and followed them up prospectively until April 2010. Results  A total of 47.5% of 423 health workers attended the program. The cohort (female-to-male ratio: 2.2; mean age: 39 years) consisted mostly of auxiliary staff (43%) and nurses (29.8%). At initial screening, 71% were asymptomatic. HIV infection (28.4%) and tuberculosis (TB) (21%) were the main reported antecedent illnesses. Laboratory screening revealed anaemia (haemoglobin level <10 mg/dl) in 9% participants, abnormal liver enzymes in 23.9% and a reactive non-treponemal syphilis test in 5%. Of 145 performed chest X-rays, 13% showed abnormalities. All 113 health workers not recently tested for HIV were screened, and 31 were newly diagnosed with HIV infection (resulting in an overall HIV prevalence of 43.8%). Nine cases of TB were diagnosed at screening/during follow-up. In April 2010, all but one of the participants were alive. All HIV-infected health workers under antiretroviral therapy were actively followed-up. Conclusion  Serious conditions were frequently diagnosed in health workers, in particular HIV infection. Mid-term outcome was favourable within this program. Creation of screening and care services dedicated to caregivers should be of highest priority in similar African settings

Integrating HIV care into nurse-led primary health care services in South Africa: a synthesis of three linked qualitative studies

BACKGROUND: The integration of HIV care into primary care services is one of the strategies proposed to increase access to treatment for people living with HIV/AIDS in high HIV burden countries. However, how best to do this is poorly understood. This study documents different factors influencing models of integration within clinics.METHODS: Using methods based on the meta-ethnographic approach, we synthesised the findings from three qualitative studies of the factors that influenced integration of HIV care into all consultations in primary care. The studies were conducted amongst staff and patients in South Africa during a randomised trial of nurse initiation of antiretroviral therapy (ART) and integration of HIV care into primary care services - the Streamlining Tasks and Roles to Expand Treatment and Care for HIV (STRETCH) trial. Themes from each study were identified and translated into each other to develop categories and sub-categories and then to inform higher level interpretations of the synthesised data.RESULTS: Clinics varied as to how HIV care was integrated. Existing administration systems, workload and support staff shortages tended to hinder integration. Nurses' wanted to be involved in providing HIV care and yet also expressed preferences for developing expertise in certain areas and for establishing good nurse patient relationships by specialising in certain services. Patients, in turn, were concerned about the stigma of separate HIV services and yet preferred to be seen by nurses with expertise in HIV care. These factors had conflicting effects on efforts to integrate HIV care.CONCLUSION: Local clinic factors and nurse and patient preferences in relation to care delivery should be taken into account in programmes to integrate HIV care into primary care services. The integration of medical records, monitoring and reporting systems would support clinic based efforts to integrate HIV care into primary care services.</p

An ion trap built with photonic crystal fibre technology

We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787(24) quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 um and 10 um.Comment: 6 pages, 4 figure

Wittgenstein and the Variety of Vienna Circles

The Vienna Circle was, as the research of recent decades made abundantly clear, far from a homogeneous group of philosophers (nor an always harmonious one). This can be shown with regard to the way different general philosophical and cultural influences affected the views of different members, but also with regard to the way in which the doctrines of specific philosophers closely associated with the origin of logical empiricism were received. Wittgenstein is a case in point. This paper sets out, with the help of a few indicative examples, how the critical reception of the Tractatus by Hans Hahn, Philipp Frank and Otto Neurath—former members of an informal pre-World War 1 discussion group, the so-called first Vienna Circle—and by Rudolf Carnap reflected their pre-existent theoretical interests. Wittgenstein’s Tractatus contributed to their developing philosophy but was far from its foundation, contrary to what has often been presumed about the relation of Wittgenstein and the Vienna Circle