3-D-micro-ERDA microscopy of trace hydrogen distributions in diamond using a 2-D-PSD with event reconstruction

A fast-imaging technique for the total elemental hydrogen concentration distribution is described, which is helpful in the study of its chemistry and dynamics in the diamond system. The micro-scanned Heavy-Ion Elastic Recoil Detection Analysis (HI-ERDA) technique can deliver information on hydrogen distributions in three dimensions. In our system, the count rate is enhanced by use of a 2-D position and energy sensitive detector for the hydrogen recoils. Software geometry collimation and recoil energy rebinning ensure that the increased rate is in fact accompanied by an improvement in effective energy resolution. The system has been used to study the mobility and trapping behaviour of a collimated implant of hydrogen into a pre-damaged natural type IIa diamond sample as well as the mobility and trapping behaviour of collimated implants of hydrogen into diamond, which has not been pre-damaged.     

Evolution of a new nonclassical MHC class I locus in two Old World primate species

HLA-G is a nonclassical major histocompatibility complex (MHC) class I molecule that is expressed only in the human placenta, suggesting that it plays an important role at the fetal-maternal interface. In rhesus monkeys, which have similar placentation to humans, the HLA-G orthologue is a pseudogene. However, rhesus monkeys express a novel placental MHC class I molecule, Mamu-AG, which has HLA-G-like characteristics. Phylogenetic analysis of AG alleles in two Old World primate species, the baboon and the rhesus macaque, revealed limited diversity characteristic of a nonclassical MHC class I locus. Gene trees constructed using classical and nonclassical primate MHC class I alleles demonstrated that the AG locus was most closely related to the classical A locus. Interestingly, gene tree analyses suggested that the AG alleles were most closely related to a subset of A alleles which are the products of an ancestral interlocus recombination event between the A and B loci. Calculation of the rates of synonymous and nonsynonymous substitution at the AG locus revealed that positive selection was not acting on the codons encoding the peptide binding region. In exon 4, however, the rate of nonsynonymous substitution was significantly lower than the rate of synonymous substitution, suggesting that negative selection was acting on these codons.     

The suboccipital cavernous sinus

The authors studied the microsurgical anatomy of the suboccipital region, concentrating on the third segment (V3) of the vertebral artery (VA), which extends from the transverse foramen of the axis to the dural penetration of the VA, paying particular attention to its loops, branches, supporting fibrous rings, adjacent nerves, and surrounding venous structures. Ten cadaver heads (20 sides) were fixed in formalin, their blood vessels were perfused with colored silicone rubber, and they were dissected under magnification. The authors subdivided the V3 into two parts, the horizontal (V3h) and the vertical (V3v), and studied the anatomical structures topographically, from the superficial to the deep tissues. In two additional specimens, serial histological sections were acquired through the V3 and its encircling elements to elucidate their cross-sectional anatomy. Measurements of surgically and clinically important features were obtained with the aid of an operating microscope. This study reveals an astonishing anatomical resemblance between the suboccipital complex and the cavernous sinus, as follows: venous cushioning; anatomical properties of the V3 and those of the petrous-cavernous internal carotid artery (ICA), namely their loops, branches, supporting fibrous rings, and periarterial autonomic neural plexus; adjacent nerves; and skull base locations. Likewise, a review of the literature showed a related embryological development and functional and pathological features, as well as similar transitional patterns in the arterial walls of the V3 and the petrous-cavernous ICA. Hence, due to its similarity to the cavernous sinus, this suboccipital complex is here named the "suboccipital cavernous sinus." Its role in physiological and pathological conditions as they pertain to various clinical and surgical implications is also discussed.     

A date with death: management of time-based and contingent suicidal intent

OBJECTIVE: The patient who voices suicidal intent in terms of the future or in terms of certain life contingencies presents special difficulties for the therapist. The authors outline the challenges posed by this problem for assessment, clinical management, and risk management. METHOD: The authors examined and analyzed case examples from both clinical and risk-management aspects. RESULTS: Problematic cases can be grouped into categories that offer insight as to management. The authors discuss this area and offer suggestions for appropriate clinical responses to this challenge. CONCLUSIONS: The authors recommend that therapists 1) treat the expressed "date with death" as a communication to be explored, 2) explore the problem of helplessness while monitoring their own countertransference responses, 3) assess the patient's competence to inform clinicians about suicidal state, and 4) readily use involuntary commitment.     

Massive hemorrhage caused by a perforating Gianturco-Z stent resulting in an aortoesophageal fistula

Squamous cell carcinoma of the tonsil has a relatively poor prognosis. Aggressive surgery, radiation therapy and combinations of irradiation and surgery have been employed but there exists some controversy about the efficacy of these treatment modalities. The purpose of this paper is to compare the efficacy of treatment between the surgery followed by radiation therapy and the preoperative radiation therapy followed by surgical resection. The medical records of 33 patients treated for squamous cell carcinoma of the tonsil at the Department of Otolaryngology-Head and Neck Surgery, Korea University Hospital between 1989-1993 were reviewed retrospectively. None of the patients were stage I, but stage II, III, and IV were four, five, and 24 patients, respectively. There were 30 males and three females. The most common histopathology was moderately differentiated squamous cell carcinoma (20/33). The 13 patients treated initially with surgery had an overall three-year survival rate of 38.5%, and the rate for the 20 patients treated initially with radiation was 40%. The main pattern of treatment failure was a local recurrence and neck metastases, and pathologic differentiation thought to be an important prognostic factor. Complications are fewer in patients treated initially with surgery (23.1%) than patients initially treated with radiation (50.0%). There is no difference in the efficacy between the two therapeutic groups.     

On the non-destructive detection of fatigue damage in industrial aluminium alloys by positron annihilation

The average positron lifetime has been determined non-destructively and in-situ during fully symmetric push-pull fatigue experiments in the bulk material of the aluminium alloys 2024 T3 and 7075 T6 using a servo-hydraulic fatigue testing system equipped with a mobile positron beam produced by a ⁷²Se/⁷²As generator (initial activity of ≈ 0.9 MBq; average positron penetration depth ≥1 mm). Contrary to earlier investigations on stainless steel using the same experimental approach, no variation of the average positron lifetime could be observed during fatigue and neither early nor late stages of fatigue damage could be revealed. It is concluded that fatigue induced changes of the defect spectra in technologically relevant aluminium alloys are masked for the present method by saturation trapping in precipitates. A sufficiently high increase of the dislocation density and the creation of vacancy clusters must be confined to the vicinity of propagating fatigue cracks or the fatal fatigue crack. Therefore the zone with sufficient detectable fatigue damage has not enough statistical weight to modify the average positron lifetime of the aluminium alloy bulk material.