Modelling intravasation of liquid distension media in surgical simulators.

Tuchschmid S, Bajka M, Szczerba D, Lloyd B, Székely G, Harders M.

Computer Vision Laboratory, ETH Zurich, Switzerland. tuchschmid@vision.ee.ethz.ch
We simulate the intravasation of liquid distention media into the systemic circulation as it occurs during hysteroscopy and transurethral resection of the prostate. A linear network flow model is extended with a correction for non-newtonian blood behaviour in small vessels and an appropriate handling of vessel compliance. We then integrate a fast lookup scheme in order to allow for real-time simulation. Cutting of tissue is accounted for by adjusting pressure boundary conditions for all cut vessels. We investigate the influence of changing distention fluid pressure settings and of the position of tissue cuts. Our simulation predicts significant intravasation only on the venous side, and just in cases when larger veins are cut. The implemented methods allow the realistic control of bleeding for short-term and the total resulting intravasation volume for long-term complication scenarios. While the simulation is fast enough to support real-time training, it is also adequate for explaining intravasation effects which were previously observed on a phenomenological level only.
PMID: 18051122 [PubMed - indexed for MEDLINE

http://www.ncbi.nlm.nih.gov/pubmed/18051122?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

Apple Intros Super-thin MacBook Air

San Francisco (CA) - The MacBook Air was, without doubt, Apple’s worst-kept secret to date. But Steve Jobs was still able to stun the assembled crowd in the Moscone Center, presenting a notebook that fits into a letter-sized envelope.

Apple has become a master of improving the design of existing products, miniaturize the machinery under the hood and wrap everything into a sleek package. The new MacBook Air is no exception. The weight of just 3.0 pounds points to a sub-notebook, but the company was able to create a full-sized notebook for road warriors and stay within that weight limit.

The system has a maximum height of just 0.76" (and measures 0.16" at its thinnest point), integrates a 13.3" LED-backlit widescreen, a 65 nm Core 2 Duo processor with 4 MB L2 cache, an 80 GB 1.8" hard drive as well as 802.11n Wi-Fi connectivity. The only dramatic compromise Apple made with regards to the functionality of the notebook is the omission of an optical drive, which, however, can be added through an optional external USB drive.

Standard features include a backlit keyboard, an iSight camera, S-video micro DVI and USB 2.0 ports. Apple is shipping the MacBook Air with a new 45 watt power adapter and claims that the battery running time will be "up to 5 hours".

The basic version of the MacBook Air, scheduled to ship in two weeks, of the notebook is offered for $1800, which compares to starting prices of $1099 for the MacBook and $1999 for the MacBook Pro. The base price includes a 1.6 GHz Core 2 Duo 7500 processor, 2 GB of memory and an 80 GB hard drive. Apple will also be offering a $3100 1.8 GHz Core 2 Duo model, which will be equipped with a 64 GB solid state disk drive.