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Notes: It has been shown how matrix elements of the form 〈x||exp(−iHt)||y〉 which arise when using operator regularization to do perturbative calculations in quantum field theory can be evaluated using the quantum mechanical path integral (QMPI). This technique has the advantage of eliminating loop momentum integrals and algebraically complicated vertices in gauge theories. A similar (but distinct) approach of Polyakov and Strassler has been applied to one loop processes with external vector particles and is related to the string based methods of Bern and Kosower. In this article, several features of the QMPI technique are examined. First, it is demonstrated how the path ordering in the QMPI can be handled by considering a model of three interacting scalar fields, each with a distinct mass. Next, it is shown how the QMPI can be used when the external wave function is not a plane wave field. The particular case of having an exponentially damped wave function is considered. Next, a discussion of the difference between the approach of Polyakov and Strassler and that employed here is given. Finally, it is demonstrated how the QMPI can be used to considerably simplify calculations in quantum gravity. © 1995 American Institute of Physics.

Notes: We show that ion-damaged GaAs may be used to detect millimeter electromagnetic waves in photoconductive sampling gates. The semi-insulating GaAs material which was implanted with a dose of 1014 cm−2 protons at an energy of 200 keV gave a signal to noise improvement of about 11.4 dB when compared with as-grown semi-insulating GaAs. The improvement is in spite of a reduced carrier mobility in the ion-implanted material and is due to the shorter carrier lifetime and formation of ohmic contacts with the ion-damaged semi-insulating GaAs. © 1999 American Institute of Physics.

Notes: Background  There is a high incidence of primary cutaneous amyloidosis (PCA) in South America, South-east Asia and Taiwan. To date, the aetiology of PCA remains unknown, but it is believed to be multifactorial. Although most cases are sporadic, some patients have a family history. Familial aggregation and different susceptibility to PCA among ethnic groups suggest that genetic factors may play an important role in its pathogenesis. However, no genetic loci for familial PCA (FPCA) have been identified so far.Objectives  In order to identify the susceptibility gene of FPCA, we took a candidate gene approach and performed linkage analysis on chromosome 1q21.3–24.2, including the 1q23.2 region where the gene encoding serum amyloid P component (APCS) is located.Patients and methods  Nine FPCA families including 29 individuals affected with PCA were recruited for this linkage study. Initially, 11 highly polymorphic microsatellite markers spanning the region from 1q21.3 to 1q24.2 were genotyped and revealed a suggestive linkage region. This region was further fine-mapped with seven additional markers. We also re-sequenced the 2·5-kb genomic region of the APCS gene in 29 affected and 42 control individuals. Two-point and multipoint linkage analyses were performed using the LINKAGE program. Nonparametric linkage (NPL) analysis and reconstruction of haplotypes were performed with the GENEHUNTER program.Results  Both two-point and multipoint linkage analysis for all 11 markers generated negative or small positive total lod scores for all nine families. However, when we considered only three families, a maximum two-point total lod score of 2·09 was obtained for the marker D1S2844 at θ = 0·01. A plateau of multipoint total lod score between D1S2768 and D1S2878 with a maximum of 2·48 at the marker D1S2844 was observed. A maximum NPL score of 3·11 (P = 0·008) was also obtained for the marker D1S2878. However, re-sequencing of the APCS gene identified no functional mutation.Conclusions  Both parametric and nonparametric linkage evidence suggested that a possible susceptibility locus for a subset of FPCA might exist on chromosome 1q23. This is the first report demonstrating suggestive evidence of linkage of FPCA to a locus in this candidate region. No functional sequence variations of the APCS gene were found to be associated with this disease among the study families. Our data imply the existence of at least one additional locus responsible for FPCA in these families, confirming genetic heterogeneity of this skin disorder.

Notes: A systems analysis technique, called the ‘analytic hierarchy process’, has been employed to develop a wastewater treatment optimization model which enables consideration to be given to subjective factors such as socio-cultural and environmental conditions as well as to technical and economic aspects. The model is particularly applicable to the developing world. Twenty and twenty-two parameters were identified for the selection of wastewater and sludge-treatment alternatives respectively. Forty-six and ninety-four treatment alternatives were formulated as decision variables for the selection for wastewater and sludge treatment respectively. The technique was then employed to select the optimum treatment procedures.

Notes: Abstract Two-photon photoemission is a promising new technique that has been developed for the study of electron dynamics at interfaces. A femtosecond laser is used to both create an excited electronic distribution at the surface and eject the distribution for subsequent energy analysis. Time- and momentum-resolved two-photon photoemission spectra as a function of layer thickness fully determine the conduction band dynamics at the interface. Earlier clean surface studies showed how excited electron lifetimes are affected by the crystal band structure and vacuum image potential. Recent studies of various insulator/metal interfaces show that the dynamics of excess electrons are largely determined by the electron affinity of the adsorbate. In general, electron dynamics at the interface are influenced by the substrate and adlayer band structures, dielectric screening, and polaron formation in the two-dimensional overlayer lattice.

Notes: We audited and analysed the adverse effects and safety of postoperative pain management on 2509 consecutive patients under care of the Acute Pain Service at a tertiary referral teaching hospital over a 32-month period. Our standard respiratory monitoring consisted of continuous pulse oximetry, hourly respiratory rate counting, sedation scoring and intermittent arterial blood gas sampling. This protocol was reliable and detected six episodes of bradypnoea, 13 of hypercapnia and 23 of oxygen desaturation occurring in 39 patients (1.8% of all spontaneously breathing patients). Two patients required naloxone injection and none had long-term sequelae. Hypotension due to epidural bupivacaine 0.0625% and fentanyl 3.3 μg.ml−1 infusion occurred in four patients (1.2%), all with a sensory block higher than T5. They readily responded to fluid infusion and ephedrine (two patients). Postoperative nausea or vomiting occurred in 723 (28.8%) and 380 (15.1%) patients, respectively. Odds ratio analysis showed that the risk factors for postoperative nausea and vomiting were: female gender, gynaecological operations, nongeriatric patients and systemic analgesia. Postoperative nausea and vomiting decreased analgesic efficacy by discouraging the use of patient-controlled analgesia and was regarded as equally distressing as pain. Other side-effects included: pruritus in 182 patients; dizziness in 333 and lower limb weakness in 73 (21.2% of patients receiving epidural local anaesthetics). It is concluded that a standard monitoring and management protocol, an experienced nursing team and reliable Acute Pain Service coverage is mandatory for the safe use of modern analgesic techniques.