Simulation Studies of the NLC with Improved Ground Motion Models

The performance of various systems of the Next Linear Collider (NLC) have been studied in terms of ground motion using recently developed models. In particular, the performance of the beam delivery system is discussed. Plans to evaluate the operation of the main linac beam-based alignment and feedback systems are also outlined.Comment: Submitted to XX International Linac Conferenc

NLC Luminosity as a Function of Beam Parameters

Realistic calculation of NLC luminosity has been performed using particle tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various values of beam emittance, energy and beta functions at the Interaction Point (IP). Results of the simulations are compared with analytic luminosity calculations. The optimum range of IP beta functions for high luminosity was identified.Comment: 4 pages, 7 figure

Beam-based Feedback Simulations for the NLC Linac

Extensive beam-based feedback systems are planned as an integral part of the Next Linear Collider (NLC) control system. Wakefield effects are a significant influence on the feedback design, imposing both architectural and algorithmic constraints. Studies are in progress to assure the optimal selection of devices and to refine and confirm the algorithms for the system design. We show the results of initial simulations, along with evaluations of system response for various conditions of ground motion and other operational disturbances.Comment: 3 pages. Linac2000 conferenc

Tuning Knobs for the NLC Final Focus

Compensation of optics errors at the Interaction Point (IP) is essential for maintaining maximum luminosity at the NLC. Several correction systems (knobs) using the Final Focus sextupoles have been designed to provide orthogonal compensation of linear and the second order optics aberrations at IP. Tuning effects of these knobs on the 250 GeV beam were verified using tracking simulations.Comment: 4 pages, 3 figure

Acute hospitalisation needs of adults admitted to public facilities in the Cape Town Metro district

Introduction. Public health care delivery in South Africa aims to provide equitable access at the most appropriate level of care. We studied to what extent the acute health care needs of adults admitted to public hospitals in the Cape Town Metropole were being appropriately met. Methods. A retrospective study was conducted of the hospital records of adults admitted to medical beds in public hospitals in Cape Town between August and November 2008. Intensive care unit patients were not included. Results. Of 802 beds in use, the estimated occupancy was at least 95%. The average time elapsed since admission was 7.9 days; 94.3% of medical admissions were acute; 45% were severely to critically ill on admission; and co-morbid disease was present in 78.1%. Of all admissions, 31.9% were HIV-positive, and 17% had active tuberculosis. At least 396 (51.6%) patients were deemed to have required specialist or subspecialist consultation to expedite appropriate care; 386 (50.3%) accessed the appropriate level of medical care required; 339 (44.2%) accessed a more sophisticated level of care than required; and 42 (5.5%) did not access an adequate level of care. CT scan and ultrasound accounted for 59% of all restricted tests done. Conclusions. Our findings support the plan to provide more primary care hospital facilities in the metropolitan area. Most patients needing specialised care are accessing such care, and most patients accessing a higher level of care than needed can be addressed by ensuring that they first access primary care and are referred according to protocols

Scaling Laws for e+e−e^+ e^- Linear Colliders

Design studies of a future TeV e+e- Linear Collider (TLC) are presently being made by five major laboratories within the framework of a world-wide collaboration. A figure of merit is defined which enables an objective comparison of these different designs. This figure of merit is shown to depend only on a small number of parameters. General scaling laws for the main beam parameters and linac parameters are derived and prove to be very effective when used as guidelines to optimize the linear collider design. By adopting appropriate parameters for beam stability, the figure of merit becomes nearly independent of accelerating gradient and RF frequency of the accelerating structures. In spite of the strong dependence of the wake-fields with frequency, the single bunch emittance preservation during acceleration along the linac is also shown to be independent of the RF frequency when using equivalent trajectory correction schemes. In this situation, beam acceleration using high frequency structures becomes very advantageous because it enables high accelerating fields to be obtained, which reduces the overall length and consequently the total cost of the linac

Acute hospitalisation needs of adults admitted to public facilities in the Cape Town Metro district

INTRODUCTION: Public health care delivery in South Africa aims to provide equitable access at the most appropriate level of care. We studied to what extent the acute health care needs of adults admitted to public hospitals in the Cape Town Metropole were being appropriately met. METHODS: A retrospective study was conducted of the hospital records of adults admitted to medical beds in public hospitals in Cape Town between August and November 2008. Intensive care unit patients were not included. RESULTS: Of 802 beds in use, the estimated occupancy was at least 95%. The average time elapsed since admission was 7.9 days; 94.3% of medical admissions were acute; 45% were severely to critically ill on admission; and co-morbid disease was present in 78.1%. Of all admissions, 31.9% were HIV-positive, and 17% had active tuberculosis. At least 396 (51.6%) patients were deemed to have required specialist or subspecialist consultation to expedite appropriate care; 386 (50.3%) accessed the appropriate level of medical care required; 339 (44.2%) accessed a more sophisticated level of care than required; and 42 (5.5%) did not access an adequate level of care. CT scan and ultrasound accounted for 59% of all restricted tests done. CONCLUSIONS: Our findings support the plan to provide more primary care hospital facilities in the metropolitan area. Most patients needing specialised care are accessing such care, and most patients accessing a higher level of care than needed can be addressed by ensuring that they first access primary care and are referred according to protocols

One-year mortality after hospital admission as an indicator of palliative care need: A retrospective cohort study

Background. Globally there is increasing awareness of the need for end-of-life care and palliative care in hospitalised patients who are in their final year of life. Limited data are available on palliative care requirements in low- and middle-income countries, hindering the design and implementation of effective policies and health services for these patients.Objectives. To determine the proportion of patients who die within 1 year of their date of admission to public hospitals in South Africa (SA), as a proxy for palliative care need in SA.Methods. This was a retrospective cohort study using record linkage of admission and mortality data. The setting was 46 acute-care public hospitals in Western Cape Province, SA.Results. Of 10 761 patients (median (interquartile range (IQR)) age 44 (31 - 60) years) admitted to the 46 hospitals over a 2-week period in March 2012, 1 570 (14.6%) died within 1 year, the majority within the first 3 months. Mortality rose steeply with age. The median (IQR) age of death was 57.5 (45 - 70) years. A greater proportion of patients admitted to medical beds died within 1 year (21.3%) compared with those admitted to surgical beds (7.7%).Conclusions. Despite a median age <60 years at admission, a substantial percentage of patients admitted to public sector hospitals in SA are in the final year of their lives. This finding should be seen in the context of SA’s high communicable and non-communicable disease burden and resource-limited public health system, and highlights the need for policy development, planning and implementation of end-of-life and palliative care strategies for hospitals and patients.

Emittance Growth during Bunch Compression in the CTF-II

Measurements of the beam emittance during bunch compression in the CLIC Test Facility (CTF-II) are described. The measurements were made with different beam charges and different energy correlations versus the bunch compressor settings which were varied from no compression through the point of full compression and to over-compression. Significant increases in the beam emittance were observed with the maximum emittance occuring near the point of full (maximal) compression. Finally, evaluation of possible emittance dilution mechanisms indicate that coherent synchrotron radiation was the most likely cause