System for calibrating pressure transducer

A system for calibrating a pressure transducer which has a reference portion and an active portion is reported. A miniature selector valve is positioned immediately adjacent the pressure transducer. A reference pressure, known pressure, and unknown pressure can be selectively admitted to the active side of the pressure transducer by the selector valve to enable calibration of the transducer. A valve admits pressure to the selector valve which has a piston and floating piston arrangement which allows proper selection with very small linear movement

Impact of mechanical bowel preparation in elective colorectal surgery: a meta-analysis

AIM: To analyse the effect of mechanical bowel preparation vs no mechanical bowel preparation on outcome in patients undergoing elective colorectal surgery. METHODS: Meta-analysis of randomised controlled trials and observational studies comparing adult patients receiving mechanical bowel preparation with those receiving no mechanical bowel preparation, subdivided into those receiving a single rectal enema and those who received no preparation at all prior to elective colorectal surgery. RESULTS: A total of 36 studies (23 randomised controlled trials and 13 observational studies) including 21568 patients undergoing elective colorectal surgery were included. When all studies were considered, mechanical bowel preparation was not associated with any significant difference in anastomotic leak rates (OR = 0.90, 95%CI: 0.74 to 1.10, p = 0.32), surgical site infection (OR = 0.99, 95%CI: 0.80 to 1.24, p = 0.96), intraabdominal collection (OR = 0.86, 95%CI: 0.63 to 1.17, p = 0.34), mortality (OR = 0.85, 95%CI: 0.57 to 1.27, p = 0.43), reoperation (OR = 0.91, 95%CI: 0.75 to 1.12, p = 0.38) or hospital length of stay (overall mean difference 0.11 d, 95%CI: -0.51 to 0.73, p = 0.72), when compared with no mechanical bowel preparation, nor when evidence from just randomized controlled trials was analysed. A sub-analysis of mechanical bowel preparation vs absolutely no preparation or a single rectal enema similarly revealed no differences in clinical outcome measures. CONCLUSION: In the most comprehensive meta-analysis of mechanical bowel preparation in elective colorectal surgery to date, this study has suggested that the use of mechanical bowel preparation does not affect the incidence of postoperative complications when compared with no preparation. Hence, mechanical bowel preparation should not be administered routinely prior to elective colorectal surgery

Penetration In Granite By Jets From Shaped-charge Liners Of Six Materials

A new application of theory for three-dimensional collapse of conical liners shows why the two-dimensional analysis may offer a good approximation. Shaped-charge design parameters and rock target properties were investigated to determine their effects on penetration and breakage. Several metals, liner thicknesses, cone angles and standoff ranges for each were investigated. Effective standoff is greater for aluminum than more dense metals. Jets from the 60° monel, brass and steel liners gave the deepest penetration in granite. Jets from copper and brass liners gave equal penetration for 42° apex angles. Liners containing zinc produced small slugs or none at all. The holes in the granite were uniform and approximated right circular cones. Jet penetration velocities into granite varied from a maximum of 10,000 m/sec to a minimum of 2000 m/sec for the most effective metal jet. © 1973

A comparison of two different software packages for the analysis of body composition using computed tomography images

Objectives: Body composition analysis from computed tomography (CT) imaging has become widespread. However, the methodology used is far from established. Two main software packages are in common usage for body composition analysis, with results used interchangeably. However, the equivalence of these has not been well established. The aim of this study was to compare the results of body composition analysis performed using the two software packages to assess their equivalence. Methods: Tri-phasic abdominal CT scans from 50 patients were analysed for a range of body composition measures at the third vertebral level using OsiriX (v7.5.1, Pixmeo, Switzerland) and SliceOmatic (v5.0, TomoVision, Montreal, Canada) software packages. Measures analysed were skeletal muscle index (SMI), fat mass (FM), fat free mass (FFM) and mean skeletal muscle Hounsfield Units (SMHU). Results: The overall mean SMI calculated using the two software packages was significantly different (SliceOmatic 51.33 vs. OsiriX 53.77, p<0.0001), and this difference remained significant for non-contrast and arterial scans. When FM and FFM were considered, again the results were significantly different (SliceOmatic 33.7kg vs. OsiriX 33.1kg, p<0.0001; SliceOmatic 52.1kg vs. OsiriX 54.2kg, p<0.0001, respectively), and this difference remained for all phases of CT. Finally, when mean SMHU was analysed, this was also significantly different (SliceOmatic 32.7 HU vs. OsiriX 33.1 HU, p=0.046). Conclusions: All four body composition measures were statistically significantly different by the software package used for analysis, however the clinical significance of these differences is doubtful. Nevertheless, the same software package should be utilised if serial measurements are being performed