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Notes: We report a study of a defect responsible for the "g'' bound exciton line at 1.5112 eV that is frequently detected in photoluminescence spectra of GaAs grown by molecular beam epitaxy (MBE). A direct correlation has been observed between this line and a transition at 1.4946 eV, which is shown to result from a conduction band-to-acceptor recombination involving a shallow, unidentified acceptorlike defect that is labeled "A.'' The activation energy of the defect is 24.8±0.2 meV, about 1.7 meV lower than that of CAs acceptor. Upon hydrogenation the defect is passivated more extensively than any known shallow acceptor species in GaAs. This result is analyzed in terms of a passivation model, from which it can be inferred that the A defect is not due to a simple substitutional Group II impurity on a Ga site. Incorporation of the A defect strongly affects the luminescence properties of the material. An almost complete quenching of the donor-bound exciton lines, profound changes in the line shape and relative intensity of the free exciton recombination, and appearance of a sharp transition of unknown origin at 1.5138 eV were observed with increasing defect concentration. Apparently "donorless'' low temperature exciton recombination spectra are reported for defect-rich p-type MBE GaAs layers with donor concentrations as high as 7×1014 cm−3 and compensation ratios of ∼0.3. The dependence of the defect incorporation on MBE growth parameters is discussed. The feasibility of MBE growth of high purity, nearly shallow defect-free p-type GaAs layers at marginally As-stabilized surface conditions over an about 1–5 μm/h range of deposition rates is demonstrated.

Notes: The thermal dissociation of PH3 and NH3 injected through a Ta-based high-pressure gas-injection cell were studied. Using a quadrupole mass spectrometer, the Ta was found to effectively dissociate the PH3 into primarily P2, P4, and H2 molecules with an injector temperature as low as 550 °C. The introduction of NH3 through this same injector resulted in dissociation into N2 and H2 for an injector temperature greater than 900 °C. When NH3 and PH3 were coinjected, again P2, P4, N2, and H2 were the primary molecules produced; however, an additional dimer, PN, was also detected. The PN concentration was maximum at a cell temperature of 700 °C. This dimer was found to be an effective source for introducing nitrogen as an isoelectronic trap in GaP.

Notes: Summary Localized morphoea uncommonly occurs in a linear distribution and may present following trauma, although most cases are idiopathic. Pigmented purpuric dermatoses such as lichen aureus may also rarely occur in a linear distribution and have been associated with trauma. A middle-aged man is described who initially presented with lesions typical of lichen aureus in a linear distribution at a site exposed to chronic low-grade trauma. This eruption was transient and clinically underwent spontaneous complete resolution. Several months later he developed localized morphoea in an identical distribution. To our knowledge this is the first reported case of a pigmented purpuric dermatosis, presumably precipitated by trauma, evolving into linear morphoea.

Notes: Measurements of the torque curves and rotational hysteresis energies of anisotropic BaFe12O19 and SrFe12O19 permanent magnets have been made at 293, 178, and 77 K. From the values of the rotational hysteresis integrals it has been concluded that magnetization changes occur by an incoherent mechanism, most probably by domain-wall nucleation and displacement.

Notes: The magnetic properties of the sintered permanent magnet Sm(Co0.83Cu0.1Fe0.07)6.77 have been measured as a function of the maximum applied field and the temperature. It has been concluded that the high coercivity is due to general domain-wall pinning at heterogeneous regions within the grains and at the sinter grain boundaries.

Notes: Room-temperature measurements have been made of the variation of the intrinsic coercivity Hc of anisotropic barium ferrite and strontium ferrite permanent magnets as a function of the angle θ between the direction of measurement and the preferred axis of magnetization. For the strontium ferrite specimen the angular variation Hc vs θ was also measured at 77, 130, and 230 K. All the results showed a gradual increase in Hc with increase in θ up to a maximum and thereafter a rapid decrease to Hc=0 at θ=90°. The angular variation in coercivity was also measured after saturation parallel to the direction of measurement. An attempt has been made to interpret the results.

Notes: Objective 1. To audit the management of cervical carcinoma in the South West Region with the aim of identifying and addressing deficiencies. 2. To determine whether recent NHS restructuring has affected the provision of cancer care.Design Retrospective review of hospital case notes.Setting All hospitals in the South West Region of England.Population Three hundred and twenty-four women with a diagnosis of cervical carcinoma: 191 were diagnosed in 1989 and 133 in 1993.Main outcome measures Documentation of patient assessment and management.Results There was a mean delay of 17 days (range 0–66) from cervical smear to cytology report and 34 days (range 1–380) from general practitioner referral to attendance at a hospital clinic. Overall, 175 women (54%) had evidence of cytological assessment prior to treatment and 137 (42%) had a colpo-scopic assessment; 49% had cytological assessment and 37% had colposcopy in 1989, compared with 60% and 50%, respectively, in 1993. Excluding 49 cases of micro-invasive carcinoma, 238 case notes (86%) contained evidence of clinical examination; 195 women (71%) had had an examination under anaesthesia, 115 (42%) a chest radiograph, 123 (45%) an intravenous urogram or renal ultrasound, and 92 (33%) cystoscopy. One hundred and forty-seven women (53%) had FIGO staging recorded in the notes. As first line treatment, 69 had conservative surgery (39 for Stage IA), 138 had radiotherapy, and 107 had radical surgery. Ten had radical surgery for Stage IA but eight had a 〉 3 mm invasion or lymphatic/vascular spread. Thirty-one had Stage IB treated with radiotherapy of whom 14 were younger than 50 years of age. Following radical surgery 30% had evidence of sampling 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:14700328:BJO140:ges" location="ges.gif"/〉 10 nodes, and 9% had tumour extending to the resection margins.Conclusions Record keeping was inadequate but appeared to indicate inconsistent cytological, clinical, colposcopic and radiological assessment, leading to inappropriate clinical delays and conservative surgery. Radical surgery often appeared inadequate, but poor node sampling rates may also reflect insufficient histopathological preparation or reporting. There was a reduction in the number of new cases of cervical carcinoma diagnosed in 1993, perhaps reflecting an observed increase in cytological surveillance. No other alterations in clinical practice were observed over the four-year period. We feel it is imperative to standardise assessment throughout the region with a minimum clinical and histopathological dataset.

Notes: The degree of unintentional hydrogen passivation of acceptors in heavily C-doped GaAs (p(approximately-greater-than)1018 cm−3) grown by metalorganic chemical vapor deposition has been found to be a strong function of post-growth cool-down ambient. The carbon concentration in the GaAs and the amount of AsH3 in the cool-down ambient are the most important factors affecting passivation. Carbon acceptors can be reactivated by annealing in N2, then repassivated by heating and re-cooling in an AsH3/H2 or PH3/H2 ambient. Secondary ion mass spectrometry analysis shows that the hydrogen concentration is significantly higher in a C-doped GaAs surface layer which is exposed to the cool-down ambient than in a layer which is buried beneath n-type GaAs. This result is consistent with observations in n-p-n heterojunction bipolar transistor structures, where the fraction of C acceptors passivated in the base region is found to be less than in a single layer grown under identical conditions. Be-doped GaAs grown by gas-source molecular beam epitaxy has also been heated and cooled in AsH3-containing ambients, but no acceptor passivation is detectable by Hall effect measurements.