Analysis of defect structure in silicon. Characterization of SEMIX material. Silicon sheet growth development for the large area silicon sheet task of the low-cost solar array project

Statistically significant quantitative structural imperfection measurements were made on samples from ubiquitous crystalline process (UCP) Ingot 5848 - 13C. Important correlation was obtained between defect densities, cell efficiency, and diffusion length. Grain boundary substructure displayed a strong influence on the conversion efficiency of solar cells from Semix material. Quantitative microscopy measurements gave statistically significant information compared to other microanalytical techniques. A surface preparation technique to obtain proper contrast of structural defects suitable for quantimet quantitative image analyzer (QTM) analysis was perfected and is used routinely. The relationships between hole mobility and grain boundary density was determined. Mobility was measured using the van der Pauw technique, and grain boundary density was measured using quantitative microscopy technique. Mobility was found to decrease with increasing grain boundary density

Hip and knee arthroplasty waiting list – how accurate and fair?

Background. Resource-intensive procedures require the use of patient waiting lists in an attempt to increase fairness of access to surgery and improve surgical efficiency. Total hip and knee arthroplasty has waiting lists in excess of years. Objectives. To analyse our tertiary state institution’s hip and knee arthroplasty waiting list to assess its accuracy.Methods. At Groote Schuur Hospital, our hospital-maintained database was compared with the surgeons’ personally maintained database. Patients were then telephoned to confirm their contactability, and to discover whether they still wanted the procedure, or if they had already had it. Waiting duration and patient demographics were then calculated.Results. Of the 655 patients on the hospital waiting list, only 454 were contactable. Three hundred and nine patients still wanted the surgery, 93 had already undergone surgery and 52 no longer wanted surgery. The last group was the oldest and had had the longest waiting time. Those still waiting had waited 451 days (minimum - maximum (standard deviation), 90 - 1 593 (228.5)), those that had had surgery 371 days (0 - 1 728 (296)) and those no longer interested 523 days (138 - 1 881 (260.9)). A total of 429 patients were present on the surgeons’ list but not on the hospital list. They had had longer waiting times than those on the hospital list.Conclusion. The arthroplasty waiting list is inaccurate due to the existence of two concurrent lists and poor data management, particularly of current contact details. The unfairness of a wide range of waiting times was identified, with patients only on the surgeons’ personal database disadvantaged. These deficiencies have prompted the introduction of  a scoring-based prioritisation system incorporating clinical, radiographic and societal parameters, in an effort to improve fair and appropriate access to this high-cost care

Studying the X-ray hysteresis in GX 339-4: the disc and iron line over one decade

We report on a comprehensive and consistent investigation into the X-ray emission from GX 339-4. All public observations in the 11 year RXTE archive were analysed. Three different types of model - single powerlaw, broken powerlaw and a disc + powerlaw - were fitted to investigate the evolution of the disc, along with a fixed gaussian component at 6.4 keV to investigate any iron line in the spectrum. We show that the relative variation in flux and X-ray colour between the two best sampled outbursts are very similar. The decay of the disc temperature during the outburst is clearly seen in the soft state. The expected decay is S_Disc \propto T^4; we measure T^4.75\pm0.23. This implies that the inner disc radius is approximately constant in the soft state. We also show a significant anti-correlation between the iron line significant width and the X-ray flux in the soft state while in the hard state the EW is independent of the flux. This results in hysteresis in the relation between X-ray flux and both line flux and EW. To compare the X-ray binary outburst to the behaviour seen in AGN, we construct a Disc Fraction Luminosity Diagram for GX 339-4, the first for an X-ray binary. The shape qualitatively matches that produced for AGN. Linking this with the radio emission from GX 339-4 the change in radio spectrum between the disc and power-law dominated states is clearly visible.Comment: Accepted for publication in MNRAS, 20 pages, 17 figures. For high-res version see http://www.astro.soton.ac.uk/~r.j.dunn/publications.htm

Hip and knee arthroplasty waiting list – how accurate and fair?

Background. Resource-intensive procedures require the use of patient waiting lists in an attempt to increase fairness of access to surgery and improve surgical efficiency. Total hip and knee arthroplasty has waiting lists in excess of years. Objectives. To analyse our tertiary state institution’s hip and knee arthroplasty waiting list to assess its accuracy. Methods. At Groote Schuur Hospital, our hospital-maintained database was compared with the surgeons’ personally maintained database. Patients were then telephoned to confirm their contactability, and to discover whether they still wanted the procedure, or if they had already had it. Waiting duration and patient demographics were then calculated. Results. Of the 655 patients on the hospital waiting list, only 454 were contactable. Three hundred and nine patients still wanted the surgery, 93 had already undergone surgery and 52 no longer wanted surgery. The last group was the oldest and had had the longest waiting time. Those still waiting had waited 451 days (minimum - maximum (standard deviation), 90 - 1 593 (228.5)), those that had had surgery 371 days (0 - 1 728 (296)) and those no longer interested 523 days (138 - 1 881 (260.9)). A total of 429 patients were present on the surgeons’ list but not on the hospital list. They had had longer waiting times than those on the hospital list. Conclusion. The arthroplasty waiting list is inaccurate due to the existence of two concurrent lists and poor data management, particularly of current contact details. The unfairness of a wide range of waiting times was identified, with patients only on the surgeons’ personal database disadvantaged. These deficiencies have prompted the introduction of a scoring-based prioritisation system incorporating clinical, radiographic and societal parameters, in an effort to improve fair and appropriate access to this high-cost care

Convergent evolution of an ant-plant mutualism across plant families, continents and time

Questions: How often has dispersal of seeds by ants evolved in monocots and is the timing of origins associated with changes in the ant community or instead with the rise of forests? Are patterns in the origin of elaiosomes (the trait associated with the dispersal of seeds by ants) through time similar to those for the origins of fleshy fruits? Data studied: We estimate the timing of the origin of elaiosomes and fleshy fruits respectivelyby mapping seed morphology onto a recent phylogeny based on ndhF sequence data forthe monocots (Givnish et al., 2005). For comparison, we use fossil data on ant relativeabundance through time and phylogenetic data for the timing of the origin of seed-dispersing ant lineages. Search method: We mapped origins of both elaiosomes and fleshy fruits onto the phylogenyusing parsimony in the program Mesquite (Maddison and Maddison, 2005). We analysed therelationship between ant relative abundances, the number of origins of seed-dispersing ants, and the rate of origination of elaiosomes using randomization-based Monte Carlo regression in the program R (Cliff and Ord, 1981). Using the program Discrete (Pagel, 2006), we test whether fleshy fruits or elaiosomes and shaded forest understoreys show correlated evolution.Conclusions: Morphological features for the dispersal of seeds by ants (myrmecochory) have evolved at least twenty times within the monocots. Origins of myrmecochory are not associated with the rise of forests during the Cretaceous or with subsequent transitions of plant lineages into closed canopy habitats, nor are they contemporaneous with the origins of fleshy fruits. Instead, the origins of myrmecochory are closely associated with the rise in relative abundanceof ants (proportion of all individual insects in fossils) towards the end of the Eocene and more recently

Ecological comparison of the risks of mother-to-child transmission and clinical manifestations of congenital toxoplasmosis according to prenatal treatment protocol

We compared the relative risks of mother-to-child transmission of Toxoplasma gondii and clinical manifestations due to congenital toxoplasmosis associated with intensive prenatal treatment in Lyon and Austria, short term treatment in 51% of Dutch women, and no treatment in Danish women. For each cohort, relative risks were standardized for gestation at seroconversion. In total, 856 mother–child pairs were studied: 549 in Lyon, 133 in Austria, 123 in Denmark and 51 in The Netherlands. The relative risk for mother-to-child transmission compared to Lyon was 1·24 (95% CI: 0·88, 1·59) in Austria; 0·59 (0·41, 0·81) in Denmark; and 0·65 (0·37, 1·01) in The Netherlands. Relative risks for clinical manifestations compared with Lyon (adjusted for follow-up to age 3 years) were: Austria 0·19 (0·04, 0·51); Denmark 0·60 (0·13, 1·08); and The Netherlands 1·46 (0·51, 2·72). There was no clear evidence that the risk of transmission or of clinical manifestations was lowest in centres with the most intensive prenatal treatment

Vacuum-UV negative photoion spectroscopy of CF3Cl, CF3Br and CF3I

Using synchrotron radiation negative ions have been detected by mass spectrometry following vacuum-UV photoexcitation of trifluorochloromethane (CF$_3$Cl), trifluorobromomethane (CF$_3$Br) and trifluoroiodomethane (CF$_3$I). The anions F$^-$, X$^-$, F$_2^-$, FX$^-$, CF$^-$, CF$_2^-$ and CF$_3^-$ were observed from all three molecules, where X = Cl, Br or I, and their ion yields recorded in the range 8-35 eV. With the exception of Br$^-$ and I$^-$, the anions observed show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation. Dissociative electron attachment, following photoionization of CF$_3$Br and CF$_3$I as the source of low-energy electrons, is shown to dominate the observed Br$^-$ and I$^-$ signals, respectively. Cross sections for ion-pair formation are put on to an absolute scale by calibrating the signal strengths with those of F$^-$ from both SF$_6$ and CF$_4$. These anion cross sections are normalized to vacuum-UV absorption cross sections, where available, and the resulting quantum yields are reported. Anion appearance energies are used to calculate upper limits to 298 K bond dissociation energies for $D^0$(CF$_3$-X) which are consistent with literature values. We report new data for $D^0$(CF$_2$I$^-$-F) ≤ 2.7 ± 0.2 eV and $\Delta_fH^0_{298}$ (CF$_2$I$^+$) ≤ (598 ± 22) kJ mol$^{-1}$. No ion-pair formation is observed below the ionization energy of the parent molecule for CF$_3$Cl and CF$_3$Br, and only weak signals (in both I$^-$ and F$^-$) are detected for CF$_3$I. These observations suggest neutral photodissociation is the dominant exit channel to Rydberg state photoexcitation at these lower energies

Photosensitivity reaction from operating room lights after oral administration of 5-aminolevulinic acid for fluorescence-guided resection of a malignant glioma

Orally administered 5-aminolevulinic acid (5-ALA), which was approved in the United States in 2017, is preferentially metabolized by malignant glioma cells into protoporphyrin IX and enhances tumor visualization when using a blue light filter on an operating microscope. Photosensitivity after 5-ALA administration is a known side effect, but a photosensitivity reaction from operating room lights has not yet been documented. We report the case of a 56-year-old man with a history of previous resection of a grade II astrocytoma who presented with imaging concerning for tumor recurrence and possible malignant transformation. Repeat surgical resection utilized 5-ALA. Soon after the surgery, he developed reddening of his skin, particularly over the right side of his head and neck, with blistering and peeling in a distribution that was particularly exposed to operating room lights during surgery. No other areas of his skin experienced the same redness, blistering, or peeling. Topical lotions were applied and the skin changes resolved spontaneously over weeks. Significant photosensitivity after administration of oral 5-ALA is a rare complication, but neurosurgeons who perform fluorescence-guided tumor resection should remain cognizant of its potential association with exposure to intense light, including in the operating room. Phototoxicity typically is self-limited, but awareness is important to minimize its occurrence

Vegetated Filter Strip Removal of Cattle Manure Constituents in Runoff

Pasture runoff can contribute to elevated concentrations of nutrients, solids, and bacteria in downstream waters. The objective of this study was to determine the effects of vegetative filter strip (VFS) length on concentrations and transport of nitrogen, phosphorus, solids and fecal coliform in runoff from plots treated with cattle manure. Three plots with dimensions of 2.4 × 30.5 m were used. The upper 12.2 m of each plot was treated with cattle manure, while the lower 18.3 m acted as a VFS. Runoff produced by rainfall simulators was sampled at VFS lengths of 0, 6.1, 12.2, and 18.3 m and analyzed for total Kjeldahl nitrogen (N), ammonia N, nitrate N, total phosphorus (P), ortho-P, fecal coliforms, total suspended solids and other parameters. The VFS significantly reduced concentrations and mass transport of incoming solids, fecal coliform, and most nutrient forms, particularly P. The relationships among VFS length, concentration and mass transport were well-represented by first-order exponential decay functions. Approximately 75% of incoming total Kjeldahl N, total P, ortho-P, and total suspended solids was removed within the first 6.1 m of the filter strips. Runoff concentrations of fecal coliform concentrations entering the filter strips were as high as 2 × 107 FC/100 mL; after a filter length of 6.1 m, however, the runoff exhibited no measurable concentration of fecal coliforms. This experiment suggests that even relatively short filter strips can markedly improve quality of runoff from grassed areas receiving cattle manure