Morbidity profile of admissions to GF Jooste Hospital, Manenberg, Cape Town

Background Secondary hospitals play an important, yet overlooked, role in reflecting public health status, both locally and nationally. Relatively few reports analysing the causes of secondary hospital admissions exist, which is especially unfortunate in the case of developing countries, considering the huge numbers of admissions and people at risk. In developing countries like South Africa, the quality of records varies among institutions. Some hospitals have computerised data, while others may keep no records whatsoever. A major problem facing the quality of hospital records is the constant shortage of staff in rural and urban hospitals. Thorough documentation is essential in providing an invaluable database for researchers, but morbidity statistics are unfortunately scarce.GF Jooste Hospital in Manenberg is the busiest hospital in Cape Town – serving 1.1 million people, with 224 beds and over 12 000 admissions annually. Budgetary constraints in the South African public health sector means that providing healthcare services at higher levels than necessary is too costly. Because hospitals consume the largest share of the public healthcare budget, they have been the focus in cost cutting. In particular, the budgets of referral (tertiary or teaching) hospitals have been trimmed in order to promote primary and secondary care. It is imperative to identify those services that are required most at secondary hospitals in order to improve budgeting and, more appropriately, train doctors and medical students for the job at hand. Identifying the morbidity profile of the population for which the hospital caters can aid the optimal utilisation of the available resources, as well as focusing the continuing medical education of hospital physicians. We determined disease patterns of admissions over a three-year period (2001-2003), primarily as insight towards optimal hospital resource management.Methods A retrospective study examined ward records, totalling 36 657 admissions, from which a random sample (N=608) was selected. A stratified sample (N=462) was constructed, considering the relative proportions admitted to the wards. The International Statistical Classification of Diseases (ICD) directed diagnosis sorting. Disease prevalence was expressed as the percentage of patients allocated to each ICD category among those admitted to the hospital and respective wards and, additionally, the percentage of diagnoses for each ICD subcategory among patients assigned to each major category.Results Trauma (represented by ICD categories S/T 23% and V/X/Y 16%), specifically assault-related, was most prevalent. This was followed by circulatory diseases (22%) and infectious diseases (19%), dominated by HIV (61%) and associated diseases like TB (57%). The age of the patients ranged from 13 to 87 (mean: 40 years), with the 20 to 30-year-olds predominating. Surgical patients were younger (mean: 35 years) than medical (mean: 45 years). In the medical wards, infectious (39% in men; 38% in women) and circulatory aetiologies (39% and 41% in men and women respectively) dominated. In the surgical wards, the trend varied according to sex: assault (43%) and other injuries (61%) for males; pregnancy-related (42%) for females.Conclusion The morbidity distribution reflects the ills affecting South African urban society, with young trauma admissions predominating. The hospital's budget is insufficient, considering its population's demands.For full text click here: SA Fam Pract 2006;48(6):15-15

Compact 20-pass thin-disk amplifier insensitive to thermal lensing

We present a multi-pass amplifier which passively compensates for distortions of the spherical phase front occurring in the active medium. The design is based on the Fourier transform propagation which makes the output beam parameters insensitive to variation of thermal lens effects in the active medium. The realized system allows for 20 reflections on the active medium and delivers a small signal gain of 30 with M$^2$ = 1.16. Its novel geometry combining Fourier transform propagations with 4f-imaging stages as well as a compact array of adjustable mirrors allows for a layout with a footprint of 400 mm x 1000 mm.Comment: 7 pages, 6 figure

Switching from Electron to Hole Transport in Solution-Processed Organic Blend Field-Effect Transistors

Organic electronics became an attractive alternative for practical applications in complementary logic circuits due to the unique features of organic semiconductors such as solution processability and ease of large-area manufacturing. Bulk heterojunctions (BHJ), consisting of a blend of two organic semiconductors of different electronic affinities, allow fabrication of a broad range of devices such as light-emitting transistors, light-emitting diodes, photovoltaics, photodetectors, ambipolar transistors and sensors. In this work, the charge carrier transport of BHJ films in field-effect transistors is switched from electron to hole domination upon processing and post-treatment. Low molecular weight n-type N,N′-bis(n-octyl)-(1,7&1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDI8-CN2) was blended with p-type poly[2,5-bis(3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene] (PBTTT-C14) and deposited by spin-coating to form BHJ films. Systematic investigation of the role of rotation speed, solution temperature, and thermal annealing on thin film morphology was performed using atomic force microscopy, scanning electron microscopy, and grazing incidence wide-angle X-ray scattering. It has been determined that upon thermal annealing the BHJ morphology is modified from small interconnected PDI8-CN2 crystals uniformly distributed in the polymer fraction to large planar PDI8-CN2 crystal domains on top of the blend film, leading to the switch from electron to hole transport in field-effect transistors

Evidence for the Existence of an Effective Interfacial Tension between Miscible Fluids: Isobutyric Acid-Water and 1-Butanol-Water in a Spinning-Drop Tensiometer

We report definitive evidence for an effective interfacial tension between two types of miscible fluids using spinning-drop tensiometry (SDT). Isobutyric acid (IBA) and water have an upper critical solution temperature (UCST) of 26.3 degrees C. We created a drop of the IBA-rich phase in the water-rich phase below the UCST and then increased the temperature above it. Long after the fluids have reached thermal equilibrium, the drop persists. By plotting the inverse of the drop radius cubed (r(-3)) vs the rotation rate squared (omega(2)), we confirmed that an interfacial tension exists and estimated its value. The transition between the miscible fluids remained sharp instead of becoming more diffuse, and the drop volume decreased with time. We observed droplet breakup via the Rayleigh-Tomotika instability above the UCST when the rotation rate was decreased by 80%, again demonstrating the existence of an effective inter-facial tension. When pure IBA was injected into water above the UCST, drops formed inside the main drop even as the main drop decreased in volume with time. We also studied 1-butanol in water below the solubility limit. Effective interfacial tension values measured over time were practically constant, while the interface between the two phases remains sharp as the volume of the drop declines. The effective interfacial tension was found to be insensitive to changes in temperature and always larger than the equilibrium interfacial tension. Although these results may not apply to all miscible fluids, they clearly show that an effective interfacial tension can exist and be measured by SDT for some systems

Theory of biopolymer stretching at high forces

We provide a unified theory for the high force elasticity of biopolymers solely in terms of the persistence length, $\xi_p$, and the monomer spacing, $a$. When the force f>\fh \sim k_BT\xi_p/a^2 the biopolymers behave as Freely Jointed Chains (FJCs) while in the range \fl \sim k_BT/\xi_p < f < \fh the Worm-like Chain (WLC) is a better model. We show that $\xi_p$ can be estimated from the force extension curve (FEC) at the extension $x\approx 1/2$ (normalized by the contour length of the biopolymer). After validating the theory using simulations, we provide a quantitative analysis of the FECs for a diverse set of biopolymers (dsDNA, ssRNA, ssDNA, polysaccharides, and unstructured PEVK domain of titin) for $x \ge 1/2$. The success of a specific polymer model (FJC or WLC) to describe the FEC of a given biopolymer is naturally explained by the theory. Only by probing the response of biopolymers over a wide range of forces can the $f$-dependent elasticity be fully described.Comment: 20 pages, 4 figure

Study of structure and antireflective properties of LaF3/HfO2/SiO2 and LaF3/HfO2/MgF2 trilayers for UV applications

Abstract The aim of this paper is to study antireflective properties of the tree-layer systems LaF3/HfO2/SiO2 and LaF3/HfO2/MgF2 deposited on heated optical glass substrates. The films were evaporated by the use two deposition techniques. In first method oxide films were prepared by means of e-gun evaporation in vacuum of 5 × 10−5 mbar in the presence of oxygen. The second was used for the deposition of fluoride films. They were obtained by means of thermal source evaporation. Simulation of reflectance was performed for 1M2H1L (Quarter Wavelength Optical Thickness) film stack on an optical quartz glass with the refractive index n = 1.46. The layer thickness was optimized to achieve the lowest light scattering from glass surface covered with dioxide and fluoride films. The values of the interface roughness were determined through atomic force microscopy measurements. The essence of performed calculation was to find minimum reflectance of light in wide ultraviolet region. The spectral dispersion of the refractive index needed for calculations was determined from ellipsometric measurements using the spectroscopic ellipsometer M2000. Additionally, the total reflectance measurements in integrating sphere coupled with Perkin Elmer 900 spectrophotometer were performed. These investigations allowed to determine the influence of such film features like surface and interface roughness on light scattering