Adventitial inversion technique without the aid of biologic glue or Teflon buttress for acute type A aortic dissection

Objective: This study was performed to evaluate the clinical usefulness of the adventitial inversion technique in acute type A aortic dissection, with special attention to the impact of this procedure on the postoperative status of false lumen evaluated by computed tomographic scan. Methods: From March 2001 to November 2004, 18 consecutive patients underwent emergent surgery for acute type A aortic dissection. Supracoronary graft replacement was performed in all the patients (ascending aorta/hemiarch replacement: 13/18 = 72%, total arch replacement: 5/18 = 28%). The adventitial inversion technique was used for both the proximal and the distal stump constructions of the dissected aortic wall without the aid of Teflon felt or biologic glue. Aortic regurgitation was treated with resuspension of the aortic commissures. Results: There were two hospital deaths and the overall hospital mortality rate was 11.1%. The mean postoperative blood loss was 635 ± 214 ml and no reexploration was required in any of the patients. Postoperative computed tomography showed closure of the false lumen in aortic root, aortic arch, and proximal descending thoracic aorta in all of the surviving patients. Postoperative echocardiography demonstrated no aortic regurgitation in any of the patients. Two patients died late postoperatively from unrelated causes to aortic dissection. The remaining 14 patients are doing well without a second-stage operation for aortic root or distal aortic lesions during the follow-up period of 7–51 months (mean: 28 ± 14 months). Conclusions: The adventitial inversion technique provides an excellent immediate hemostasis and facilitates thrombotic closure of the proximal and the distal false lumen in the treatment for acute type A aortic dissection

Phonetic Drift in Fricatives and the Effects of L2 Experience on L1 Phonetic Categories

Previous research has shown that L2 learners immersed in a target language environment exhibit phonetic drift in L1 category boundaries along VOT （Chang, 2002, 2010; Tice & Woodley, 2012） and vowel formant （Guion, 2003） dimensions, which subsides after an extended duration of immersion. This study investigates the articulation of sibilant fricatives in Japanese and in English by three groups of bilinguals – a） late bilinguals who have studied abroad; b） late bilinguals with no experience abroad; c） early （simultaneous） bilinguals – to determine whether they differ from one another in distinguishing post-alveolar sibilants of English, [ʃ], and Japanese, [㷡], and whether there is evidence among late bilinguals of phonetic drift in the alveolar sibilant [s] common to both languages under pressure from the novel English post-alveolar.Participants produced real words containing each of the test segments before a high or a low vowel in four blocks, two in English and two in Japanese both in isolation and embedded within a carrier phrase. Productions were recorded and submitted to acoustic analysis. Measurements of spectral Center of Gravity (Hanulíková and Weber, 2010) revealed differences between the two languages only among late bilinguals with no study abroad experience. Without intensive immersion experience, these participants were expected to exhibit no evidence of phonetic drift; however, the pool from which they were recruited was comprised of Japanese university students majoring in linguistics with coursework in English phonetics. We therefore speculate that phonetic drift may not arise solely from intensive exposure in an immersion environment but from heightened perceptual awareness brought about through acquired metalinguistic knowledge as well. It is surmised that any experience of phonetic drift that the other two groups may have had must already have subsided by the time of testing given the extent of their exposure experience