Relay-Assisted User Scheduling in Wireless Networks with Hybrid-ARQ

This paper studies the problem of relay-assisted user scheduling for downlink wireless transmission. The base station or access point employs hybrid automatic-repeat-request (HARQ) with the assistance of a set of fixed relays to serve a set of mobile users. By minimizing a cost function of the queue lengths at the base station and the number of retransmissions of the head-of-line packet for each user, the base station can schedule an appropriate user in each time slot and an appropriate transmitter to serve it. It is shown that a priority-index policy is optimal for a linear cost function with packets arriving according to a Poisson process and for an increasing convex cost function where packets must be drained from the queues at the base station.Comment: 14 pages, 5 figures, submitted to the IEEE Transactions on Vehicular Technology in October 2008, revised in March 2009 and May 200

Laparoscopic-assisted vaginal hysterectomy with lateral transsection of the uterine vessels

Background: Increased safety and diminished blood loss are achieved through laparoscopic-assisted vaginal hysterectomy by selective coagulation and transsection of the uterine vessels at their origin. Methods: Three laparoscopic steps are performed: coagulation and transsection of the round ligament, of the uterine artery at its origin, and of the fallopian tube and ovarian ligament or (in BSO) the infundibulopelvic ligament. The uterine vessels are identified from the pararectal space and, following the internal liliac artery, and the ureter. Hysterectomy is completed transvaginally. Results: Two hundred and sixty-seven patients underwent this procedure. Mean operation time was 121 min, and hemoglobin decreased to 0.6 g/dl by postoperative day 3. It took 8.4 min on average to identify and coagulate the uterine artery. Conclusions: Lateral transsection of the uterine vessels is safe and blood sparing and can be used in patients in whom blood loss must be minimized

Laparoscopic coagulation of the uterine blood supply in laparoscopic-assisted vaginal hysterectomy is associated with less blood loss

Background: Does laparoscopic coagulation of the uterine blood supply decrease blood loss compared with transvaginal ligature of the uterine vessels? Methods: Intra- and postoperative data of 446 patients undergoing laparoscopic-assisted vaginal hysterectomy at the Department of Gynecology, University of Jena, between 1998 and 2001 were analysed. In 213 patients the uterine blood supply was transected laparoscopically at the origin of the uterine vessels (LAVH type II) and in 233 patients (LAVH type I) transvaginally. Results: Patients in both groups were comparable with respect to median age, Quetelet index, and parity. The drop of hemoglobin between the preoperative day and postoperative day 3 was 0.8 mmol/l or 0.6 mmol/l for LAVH type I without or with BSO vs 0.3 mmol/l or 0.4 mmol/l for LAVH type II without or with BSO (p = 0.001), respectively. Median operative time was similar for both techniques: LAVH type I 136 min or with BSO 128 min vs LAVH type II 126 min or with BSO 131 min. The weight of the removed uteri was significantly lower in LAVH type I vs type II (220 vs 270 grams), but similar when LAVH was combined with BSO (160 vs 178 grams). The rate of intraoperative complications was 2.2% vs 0.9% between LAVH type I or II (n.s.), but 9% vs 3.3% for overall postoperative complications (p = 0.01). Conclusions: Laparoscopic coagulation of the uterine blood supply at the origin of uterine vessels is a safe technique which minimizes blood loss in LAVH. In patients with a low preoperative hemoglobin value this technique is indicated

From laparoscopic assisted radical vaginal hysterectomy to vaginal assisted laparoscopic radical hysterectomy

Radical hysterectomy with pelvic lymphadenectomy is the standard surgical treatment for patients with early stage cervical cancer. The majority of radical hysterectomies are performed with the open technique. However, laparoscopic, combined laparoscopic and vaginal, and robotic-assisted approaches may also be used. Compared with the abdominal radical hysterectomy (ARH), laparoscopic techniques are associated with less blood loss, shorter hospital stay, better cosmesis, and faster recovery. A further breakthrough in laparoscopic technique can only be made if safety and oncological clearance are comparable with ARH. We describe the technique and results of laparoscopic assisted radical vaginal hysterectomy and the transition to vaginal assisted laparoscopic radical hysterectomy. \ua9 2011 RCOG