A constant pressure flowmeter for extreme-high vacuum.

We demonstrate operation of a constant-pressure flowmeter capable of generating and accurately measuring flows as low as 2 × 10-13 mol/s. Generation of such small flows is accomplished by using a small conductance element with C ≈ 50 nL/s. Accurate measurement then requires both low outgassing materials (< 1 × 10-15 mol/s) and small volume changes (≈ 70 µL). We outline the present flowmeter's construction, detail its operation, and quantify its uncertainty. The type-B uncertainty is < 0.2 % (k = 1) over the entire operating range. In particular, we present an analysis of its hydraulic system, and quantify the shift and uncertainty due to the slightly compressible oil. Finally, we compare our flowmeter against a NIST standard flowmeter, and find agreement to within 0.5 % (k = 2).

Prevalence of Pasteurella multocida and other respiratory pathogens in the nasal tract of Scottish calves.

The prevalence of Pasteurella multocida, a cause of bovine respiratory disease, was studied in a random sample of beef suckler and dairy farms throughout Scotland, by means of a cross-sectional survey. A total of 637 calves from 68 farms from six geographical regions of Scotland were sampled between February and June 2008. Deep nasal swabs were taken, and samples that were culture-positive for P multocida were confirmed by PCR. Prevalence of P multocida was 17 per cent (105 of 616 calves); 47 per cent of farms had at least one positive animal. A higher prevalence was detected in dairy calves than beef calves (P=0.04). It was found that P multocida was associated with Mycoplasma-like organisms (P=0.06) and bovine parainfluenza type 3 virus (BPI-3) (P=0.04), detected by culture and quantitative PCR of nasal swabs, respectively. Detection of P multocida was not associated with bovine respiratory syncytial virus (BRSV), bovine herpesvirus type 1 (BoHV-1) or bovine viral diarrhoea virus (BVDV). Mycoplasma-like organisms, BPI-3, BRSV, BoHV-1 and BVDV were detected in 58, 17, four, 0 and eight calves, on 25, five, two, 0 and five of the 68 farms, respectively.

Lung volume reduction: surgical treatment for emphysema.

BACKGROUND: Lung volume reduction surgery is currently being investigated as a method of improving the respiratory function of patients with end-stage emphysema. PURPOSE: This article reviews the current literature on lung volume reduction surgery and proposes a multidisciplinary team approach to postoperative management. METHODS: We did a MEDLINE search and retrieved relevant articles. We selected and reviewed nine medical articles published in 1993, 1995, and 1996; one medical article from 1959; and one of four nursing articles. Overall, the articles describe the different techniques of median sternotomy and video-assisted thoracoscopic surgery and unilateral versus bilateral procedures. CONCLUSION: Lung volume reduction surgery is beneficial, but further investigation is required.