Electron mobility in degenerate tellurium doped In0.53Ga0.47As LPE layers

Tellurium doped In0.53Ga0.47As epitaxial layers have been grown by LPE in the range n=1018?4×1019 cm?3; the distribution coefficient of tellurium was found to be 0.1. These layers exhibit a two to three times higher mobility than InP or GaAs doped to the same level. Theoretically calculated values of mobility taking account of the degenerate and nonparabolic conduction band conditions are compared with the experimental data.     

Disbudding of red deer stag calves to prevent antler growth

Red deer stag calves aged five to seven months were disbudded with a standard cattle disbudding iron as a means of preventing antler growth and development. Two sizes of iron, one 2.2 cm in diameter and one 1.5 cm in diameter, were compared at disbudding in November or January. Disbudding in November and January with the 2.2 cm iron had success rates of 97 per cent and 92 per cent, respectively. Treatment with the 1.5 cm iron was less effective at both times. There was no significant difference between the liveweights of the treated groups and a non-disbudded control group at turnout in the spring or at slaughter in November when the stags were 16 months of age.     

Temperature dependence of the subthreshold velocity/field characteristic for epitaxial InP

The subthreshold electron-drift-velocity/field characteristic for epitaxial InP has been measured over the temperature range 118?446 K. The threshold field of H-shaped devices is found to increase from 8 to 12.3 kV/cm and the peak velocity to decrease monotonically from 3.3×107 to 1.9×107 cm/s over this temperature interval.     

The molecular pathology of urological malignancies

BACKGROUND: Effective esophageal peristalsis is a major determinant of esophageal clearance function. The relation of esophageal body function with a mechanically defective lower esophageal sphincter and the development of esophageal mucosal injury in patients with gastroesophageal reflux disease is unclear. STUDY DESIGN: We analyzed the relations among the manometrically determined esophageal clearance function, lower esophageal sphincter dysfunction, esophageal acid exposure, and the presence and severity of esophageal mucosal injury in patients with gastroesophageal reflux disease. Normal values for the manometric assessment of esophageal clearance function were established in 50 normal volunteers and subsequently applied to 160 symptomatic patients with increased esophageal exposure to gastric juice and various grades of esophageal mucosal injury (no minimal surgery, esophagitis, stricture, and Barrett's esophagus). RESULTS: Defective clearance function was present in 47.5% of the patients; a defective lower esophageal sphincter was documented in 63.1%. Compromised esophageal clearance function was significantly more common in patients with a defective lower esophageal sphincter than in those with normal sphincter function (55% versus 33.8%). Esophageal acid exposure time and the prevalence and severity of esophageal mucosal injury were highest in patients with a defective sphincter and compromised clearance function. CONCLUSIONS: These data show that esophageal motor function deteriorates with increasing severity of mucosal injury. This appears to be due to persistent reflux of gastric juice across a mechanically defective lower esophageal sphincter. This may influence the choice and outcome of antireflux surgery. Surgical correction of a mechanically defective sphincter before the loss of esophageal body function is advocated.     

Transnasal endoscopic excision of midline nasal dermoid from the anterior cranial base

We recommend that every patient with a midline nasal dermoid be evaluated preoperatively by fine-cut CT scan, in the axial and coronal planes, using both bone and soft-tissue algorithms. Because of CT limitations for assessing soft tissue at the cranial base, a complementary thin-section, high-resolution, multiplanar MRI scan should be considered. Transnasal endoscopic excision of midline nasal dermoid should be used if the dermoid is located within the nasal cavity, and there is minimal or no cutaneous involvement. This approach can be combined with a short vertical midline lenticular excision of a cutaneous punctum. Vertical cutaneous excision should be limited; the best location is the nasal tip. Vertical nasal scars over the bony pyramid invariably widen no matter what intradermal suture is used. Endoscopic removal should be considered even if preoperative radiologic studies show extension to the anterior cranial fossa. Endoscopic excision could also be used to resect a dermoid extending between the dural leaves of anterior fossa. However, a combined intra-extracranial approach is necessary if the dermoid is in the falx cerebri. We agree with other authors that frozen sectioning the superior margin of the specimen should be done to ensure that there is no intracranial extension. Valsalva maneuver during endoscopic visualization of the cranial base is a valuable means of ruling out a cerebral spinal fluid leak.     

New polymorphic microsatellite markers place the haemochromatosis gene telomeric to D6S105

The haemochromatosis gene (HFE) is linked to both HLA-A and D6S105 on the short arm of chromosome 6 but these markers are separated by approximately 2 Mb of DNA. Most chromosomes carrying HFE have a common haplotype which extends from HLA-A to D6S105 and includes HLA-F. To localise the gene more precisely we have examined 10 microsatellite markers extending over a genetic distance of approximately 5 cM from D6S265 (within 100 kb of HLA-A on the centromeric side) to D6S299 (telomeric). The order of markers is D6S265, HLA-F, D6S258, D6S306, CS3, D6S105, D6S464, CS5, D6S461 and D6S299. We confirm that haemochromatosis appears to originate from a founder mutation which has multiplied in the population through successive generations. This mutation is associated with the haplotype D6S306-5, CS3-3, D6S105-8, D6S464-9 and CS5-4 which is found on approximately 70% of HFE chromosomes. We have applied a new and powerful, likelihood analysis for linkage disequilibrium. The maximum value of lambda (proportion of total possible association between a marker and disease) is 0.74 for marker CS5 (allele 4). A multipoint analysis also gives a maximum likelihood near marker CS5. We conclude that the HFE gene is likely to be located telomeric of D6S105 and close to CS5.     

Recurrent hypernatremia; a proposed mechanism in a patient with absence of thirst and abnormal excretion of water

A 7-year-old girl twice developed severe hypernatremia (serum sodium values up to 194 mEq/l) without obvious cause. The ability of her kidneys to conserve water was normal, and increasing her plasma osmolality stimulated an appropriate ADH response. Unable to excrete a water load, her kidneys continued to conserve water even with a serum sodium concentration of 133 mEq/l. She was never thirsty and did not ingest sufficient fluid by choice. Although there was no demonstrable anatomic lesion, we postulate a localized defect of her thirst center. This may have modified release of ADH and resulted in an inability to dilute the urine by interrupting a pathway that could exist from the thirst center to the supraoptic nuclei. A therapeutic regimen based on these studies has prevented further hypernatremia.     

Estimation of rib waveguide radiation losses

An estimative procedure given recently for approximating radiation losses from indiffused waveguides is adapted to rib waveguides and compared with a recent Huygens-type solution for bending loss. The implications for the wider application of the estimative procedure are favourable     

Surface-wave probe for measuring electron densities in a gaseous plasma

A dielectric rod enveloped in gaseous plasma can act as a supporting structure for electromagnetic surface waves. The dielectric constant of the plasma and hence the electron number density in the vicinity of the rod may be determined from measurements of the phase-change coefficient of the EH11 mode supported by the plasma-clad rod. Measurements of radial density distribution have been carried out in an unmagnetised argon afterglow plasma at 35Gc/s and compared with double-probe measurements.