Estimating relative abundance of whales from historical Antarctic whaling records

Catch per unit effort (CPUE) is often the only data available from historical fisheries for inferring distribution and abundance of exploited populations. CPUE underestimates variations in relative abundance when gross effort data are only measured in total operating days. Gross effort includes both searching time and handling time, but only searching time is useful for an index of abundance. A method is developed for estimating searching time by subtracting a maximum likelihood estimate of handling time from the gross effort. An expectation maximization (E-M) algorithm is used to combine maximum likelihood estimates of the handling time with the expected additional operating time due to handling the last catch of each day. Simulation tests show that the estimates of catch per unit of searching time (C/CSW) are much closer to proportionally related to local density than gross CPUE. Estimates of handling time are not unbiased, and some nonlinearity between local density and C/CSW may persist. The methods may be useful for other fisheries where historic gross catch and effort data involve both searching and handling.

An Assessment of the Tensile Properties and Technical Difficulties of Two- and Four-Strand Flexor Tendon Repairs

This study compares the mechanical properties of locking Kessler and four-strand flexor tendon repairs and examines for difficulties related to technical ability. Two trainee surgeons each carried out 10 locking Kessler and 10 four-strand single-cross flexor tendon repairs on an in vitro porcine model. Outcome measures included gap formation and ultimate forces, operative time and repair bulk. Ultimate force was 81% greater for the four-strand repair compared to the Kessler (52 N, SD 5, versus 29 N, SD 6). Operating times were similar between the two techniques (Kessler 10.0 minutes, four strand 10.1 minutes). Rupture force and operating times improved slightly during the study for the Kessler repairs, but in the four strand repairs results remained stable throughout the study. We conclude that the single-cross four-strand repair tolerates superior loads yet is no more technically demanding than the modified Kessler, and can be reliably performed without additional operating time.

Craniotomy Revisited: Techniques for Improved Access and Reconstruction

ABSTRACT:Objective:To describe simple modifications of the technique of opening and closure of the craniotomy to improve basal exposure and reconstruction.Methods:The modifications involve: a) additional soft-tissue dissection which is carried downward to the base of the ear and to the orbital rim, exposing the orbital rim and malar eminence without removing the bone; b) cutting the bone flap so that ‘bridges’ of bone remain that help to stabilize the flap when it is returned to the cranium at the end of the operation; c) the wedging of bone chips between the bone flap and native cranium at the time the bone is being reaffixed so as to provide firm stability by diminishing movement of the bone flap; d) the use of bone dust and bone chips mixed with the patient's blood to seal and bridge the gap between the bone flap and the native bone; e) reattachment of the temporalis muscle with the bone flap sutures. An ‘inlay’ technique of duraplasty is also described.Results and Conclusion:These simple modifications of craniotomy provide better basal exposure and reconstruction with little additional operating time at no additional cost.

Bridged craniotomy for stable fixation of a bone flap

✓ Postoperative depression of the bone flap is a common and bothersome problem in craniotomies. In this paper, a simple technique to avoid this deformity is described. The key to this technique is to leave uncut a part of each osteotomy approximately 5 mm in width as a “bridge” to the bone flap, which is then subsequently cut with the aid of a chisel. This technique provides stable fixation of the bone flap and satisfactory cosmetic results with little additional operating time.

Temporal muscle microfixation in pterional craniotomies

✓ Temporal muscle asymmetry is a common sequela of pterional craniotomies. The authors describe a simple technique of restoring the temporal muscle to its origin by microscrew fixation. This technique provides reliable preservation of temporal muscle bulk and function with little additional operating time and no compromise of operative exposure.