Theoretical Study of Friction: A Case of One-Dimensional Clean Surfaces

A new method has been proposed to evaluate the frictional force in the stationary state. This method is applied to the 1-dimensional model of clean surfaces. The kinetic frictional force is seen to depend on velocity in general, but the dependence becomes weaker as the maximum static frictional force increases and in the limiting case the kinetic friction gets only weakly dependent on velocity as described by one of the laws of friction. It is also shown that there is a phase transition between state with vanishing maximum static frictional force and that with finite one. The role of randomness at the interface and the relation to the impurity pinning of the sliding Charge-Density-Wave are discussed. to appear in Phys.Rev.B. abstract only. Full text is available upon request. E-mail: [email protected]: 2 pages, Plain TEX, OUCMT-94-

Clinical Results of Flow Diverter Treatments for Cerebral Aneurysms under Local Anesthesia

Flow diverters (FD) have become the mainstay for the endovascular treatment of unruptured intracranial aneurysms (UIA). Most FD procedures are performed under general anesthesia, and the influence of local anesthesia (LA) on outcomes remains unknown. This study evaluated the results of FD placement under LA. Data of patients treated for FD under LA between August 2016 and January 2022 were analyzed retrospectively. A good outcome was defined as a modified Rankin scale score of 0–2. Major stroke, steno-occlusive events of FD, mortality, and satisfactory aneurysm occlusion were also evaluated. In total, 169 patients undertook 182 treatments (139 [82%) female, mean age 61 ± 11 years). The median maximum aneurysm size was 9.5 mm (interquartile range 6.1-14 mm). A flow re-directed endoluminal device and pipeline embolization device were used in 103 (57%) and 78 (43%) treatments. One patient (0.59%) experienced major stroke, and steno-occlusive events were observed in four patients (2.4%). A good outcome at 90 days was obtained in 164 patients (98%), and one patient died (0.59% mortality). During the median follow-up period of 345 days (interquartile range 176–366 days), satisfactory aneurysm occlusion was observed in 126 of 160 aneurysms (79%). Our results suggest that FD placement under LA is a safe and effective treatment for UIA

Toward a more rationalized use of a special technique for repair of frontal air sinus after cerebral aneurysm surgery: The most effective technique

A craniotomy that passes through the frontal air sinus (FAS) often results in postoperative complications such as infection, cerebrospinal fluid leakage or mucocele formation. A good understanding of FAS reconstruction can decrease the morbidity rate of complications. This study describes the outcomes of treatment and establishes the most effective technique for FAS reconstruction in our institution. We enrolled 107 patients who had a bifrontal craniotomy which exposed the FAS during the operation for an anterior communicating artery (ACoA) aneurysm. Demographic data including the follow-up information were collected and analyzed. The complications after surgery were observed and described in the treatment procedure. The patency of the nasofrontal outflow tract (NFOT) was proved by removal of blood clots and bone dust by irrigation and by direct inspection under a microscope before closure of the frontal sinus mucosa with a monofilament non-absorbable 7/0 material suture. The dura was closed in a watertight fashion and an abdominal fat graft was packed into the FAS cavity. There were 33 male and 74 female patients and the mean age (range) was 64 years (32–90 years). The mean follow-up time was 13 months (1–35 months) and complications were found in only 2 patients. One patient suffered from dislocation of the fat graft and the other patient developed a surgical wound infection. At post-operation the first patient sneezed several times and the second patient suffered from trauma in the nasal area after discharge to home. Both patients were surgically treated and cured. In conclusion, FAS reconstruction from our technique is very effective for the prevention of complications after bifrontal craniotomy. Direct suturing of the frontal sinus mucosa and proving the patency of the NFOT are keys to successful treatment