3,164 research outputs found
Ground states of large bosonic systems: The gross-pitaevskii limit revisited
We study the ground state of a dilute Bose gas in a scaling limit where the
Gross-Pitaevskii functional emerges. This is a repulsive non-linear
Schr\"odinger functional whose quartic term is proportional to the scattering
length of the interparticle interaction potential. We propose a new derivation
of this limit problem, with a method that bypasses some of the technical
difficulties that previous derivations had to face. The new method is based on
a combination of Dyson's lemma, the quantum de Finetti theorem and a second
moment estimate for ground states of the effective Dyson Hamiltonian. It
applies equally well to the case where magnetic fields or rotation are present
Liver resection by Ultrasonic Dissection and lntraoperative Ultrasonography
Ultrasonic dissetion (USD) and intraoperative ultrasonography (IOUS) have shown encouraging results
in a retrospective analysis of 109 patients with benign or malignant liver disease. Of 109 patients assessed
between 1980 and 1993, 84 were resected: 27 by finger fracture technique (FFT) and 57 by USD. Hospital
mortality was 4.8% (4/84) and 30-day mortality was 6.0% (5/84). Overall morbidity was 48.8% (41/84)
and liver related morbidity (hepatic bleeding, sepsis, and bile leak) was 34.5% (29/84); of the 29 patients,
5 required re-operation. Liver complications occurred in 12/27 (44.4%) in the FFT group as opposed to
17/57 (29.8%) in the USD group. The incidence of postoperative hepatic bleeding was significantly less
by USD than by FFT(p=O.03). As well, intraoperative blood loss (p=O.01)number of intraoperative
blood units used (p=0.002), and postoperative length of stay (p=O.O09) have been significantly reduced
by USD. IOUS was used on 64 patients. Not only has it improved the sensitivity (99%) and specificity
(98%) for detection of hepatic neoplasms, it has also helped increase the precision and accuracy of
anatomical tumour localization. As a result, 11/64 patients (17.2%) had their preoperative plans
changed: 8 were abandoned and 3 were revised. In summary, USD has significantly reduced
intraoperative blood loss and hence reduced the number of intraoperative transfusions, incidence of
postoperative complications and postoperative length of stay. IOUS should be routinely employed in
patients undergoing liver resection since it provides critical information that could obviate oncologically
useless resections
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