An optically heated atomic source for compact ion trap vacuum systems.

We present a design for an atomic oven suitable for loading ion traps, which is operated via optical heating with a continuous-wave multimode diode laser. The absence of the low-resistance electrical connections necessary for Joule heating allows the oven to be extremely well thermally isolated from the rest of the vacuum system. Extrapolating from high-flux measurements of an oven filled with calcium, we calculate that a target region number density of 100 cm-3, suitable for rapid ion loading, will be produced with 175(10) mW of heating laser power, limited by radiative losses. With simple feedforward to the laser power, the turn-on time for the oven is 15 s. Our measurements indicate that an oven volume 1000 times smaller could still hold enough source metal for decades of continuous operation.

Modeling and underwater characterization of cymbal transducers and arrays.

The cymbal is a miniaturized class V flextensional transducer that was developed for potential use as a shallow water sound projector and receiver. Single elements are characterized by high Q, low efficiency, and medium power output capability. Its low cost and thin profile allow the transducer to be assembled into large flexible arrays. Efforts were made to model both single element and transducer arrays by coupling finite element analysis (ATILA) and the integral equation formulation (EQI). The pressure and velocity distributions on the surface elements were calculated by ATILA and later used with EQI to calculate the far field properties of the transducer element and arrays. It eliminates the mesh of the fluid domain and makes the 3-D model of a transducer possible. Three-dimensional models of a cymbal transducer and a 3 x 3 cymbal array were developed in the modeling. Very good agreement was obtained between modeling and measurement for single element transducers. By coupling finite element analysis with the integral equation method using boundary elements, acoustic interaction effects were taken into account. Reasonable agreement was obtained between calculation and measurement for a 3 x 3 array.

A miniature class V flextensional cymbal transducer with directional beam patterns: the double-driver.

The "double-driver" cymbal, a directional class V flextensional transducer, is described in this paper. Its basic structure is a bilaminar piezoelectric disk with metal caps as mechanical transformers and amplifiers. The directivity was accomplished by exciting the double-driver in a combined flexural and bending mode causing the sound pressure to add in one direction and cancel in the opposite direction. The cardioid beam pattern predicted by finite element modeling agreed well with the experimental measurements. A 3 x 3 double-driver array was constructed to demonstrate that under optimal conditions the array can provide a directional beam pattern with a front-to-back ratio of more than 20 dB.

Cymbal array: a broad band sound projector.

A prototype 3 x 3 planar cymbal transducer array was built and tested. The array has a radiating area of 5.5 cm x 5.5 cm and a thickness of less than 8 mm. The measured transmitting voltage response was above 134 dB re 1 microPa/V @ 1 m and flat over the frequency range of 16 and 100 kHz. Array interaction was analyzed using an equivalent circuit model. The array interaction leads to variations in radiation resistance and velocity of the transducers in the array according to their surroundings in the array. The effect is enhanced overall efficiency and a flat response.

Postoperative morbidity and mortality following resection of the colon and rectum for cancer.

PURPOSE: The aim of this study was to report the prevalence of postoperative complications and mortality of patients with colorectal cancer when treated by conventional surgery. METHODS: Morbidity and mortality following open resection for colorectal cancer were analyzed in 1,846 patients whose clinical, operative, and pathology data were prospectively documented over a 20-year period. RESULTS: Mortality following elective resection of the left and right colon was low, whereas overall morbidity was high (37.2 percent). Respiratory and cardiac complications were especially common. Incidence of clinically significant leakage was similar following right (0.5 percent) or left (1.1 percent) hemicolectomy. Incidence of anastomotic leakage was significantly higher after emergency right hemicolectomy (4.3 percent). Overall morbidity following excision of the rectum was high (40.2 percent). Respiratory and cardiac complications predominated. Incidence of clinically significant anastomotic leakage following anterior resection was low (2.9 percent). Over the years, there has been a decline in the number of patients with tumor demonstrated histologically in a line of resection, suggesting an improved local surgical clearance. CONCLUSIONS: These results following conventional surgery may be useful when evaluating new techniques.

Hartmann's procedure for carcinoma of the rectum and sigmoid colon.

A review of the Hartmann's operation for patients with rectal and sigmoid cancer over an 18 year period is presented. There were 1063 patients who had a resection for carcinoma of the rectum or sigmoid colon and 4.4% of these had a Hartmann's procedure. This operation was particularly useful in the management of patients who presented with a proximal obstruction or perforation at the tumour site. It was also effective in the elective treatment of elderly unfit patients who had locally advanced tumours or those with distant metastases. Re-anastomosis is recommended in those patients who are relatively fit and have had a potentially curative resection.

Morbidity, mortality and survival following resection for carcinoma of the rectum at Concord Hospital.

Colorectal cancer is the most common internal malignancy in Australia, and the rectum is the most common site. The morbidity, mortality and survival of 561 consecutive patients with rectal cancer who had a resection at Concord Hospital during the 16-year period 1971-86 were evaluated. More than half of the operations performed were low anterior resections (LAR), with total abdominoperineal excisions (APE) of the rectum comprising another third. There was a 5.1% mortality rate in LAR patients and a 3.1% mortality rate in the APE group. Respiratory complications, urinary tract infections and wound infections were the most common causes of morbidity in both LAR and APE. The median survival for patients treated by LAR and APE standardized for clinicopathological staging was 111.5 and 47.1 months (A), 79.0 and 65.5 months (B), 41.3 and 28.5 (C), and 14.7 and 12.4 (D), respectively.

Local recurrence following anterior resection for carcinoma of the rectum with a stapled anastomosis.

Forty-four patients underwent an anterior resection for carcinoma of the rectum using the EEA stapling device. After a two-year follow-up period, two patients had developed a local recurrence alone, and four a local recurrence in the presence of disseminated disease. These were compared to a group of 108 patients with carcinoma of the rectum who had an anterior resection with a hand-sewn anastomosis. There was no difference in the incidence of local recurrence between the two groups.