The complete AdS3 ×S3 × T4 worldsheet S matrix

We derive the non-perturbative worldsheet S matrix for fundamental excitations of Type IIB superstring theory on AdS3 ×S3 × T4 with Ramond-Ramond flux. To this end, we study the off-shell symmetry algebra of the theory and its representations. We use these to determine the S matrix up to scalar factors and we derive the crossing equations that these scalar factors satisfy. Our treatment automatically includes fundamental massless excitations, removing a long-standing obstacle in using integrability to study the AdS3/CFT2 correspondence

Regeneration and repair of peripheral nerves

Posttraumatic nerve repair continues to be a major challenge in restorative medicine and microsurgery. Although progress has been made in surgical techniques over the last 30 years, functional recovery after a severe lesion of a major nerve trunk is often incomplete and often unsatisfactory. Functional recovery after surgical repair of mixed nerves is even more disappointing. Functional recovery after peripheral nerve lesion is dependent upon accurate regeneration of axons to their original target tissues. Thus, in order to enhance regeneration, a better understanding of the cellular and molecular biology of selective nerve regeneration is required. Schwann cells and their endoneurial extracellular matrix play pivotal roles in the selective promotion of motor and sensory axon regeneration. Knowledge of these mechanisms allows for the better development of biocompatible nerve grafting material. (c) 2005 Elsevier Ltd. All rights reserved

HEMODYNAMIC AND HISTOLOGICAL DIFFERENCES IN END-TO-SIDE ANASTOMOSES

An end-to-side anastomosis is often a necessity in replantation surgery. This study examines the effects of elliptical versus slit arteriotomy and the angle of anastomosis on vessel patency and aneurysm formation. Forty male rats were divided into four groups of ten rats each. The right and left common iliac arteries were selected as a model. The results showed no significant statistical difference in patency rates among our four experimental groups. The end-to-side anastomotic technique of choice uses the elliptical arteriotomy placed at a 90-degrees angle. It provides good visualization and easy suture placement

Surgical treatment of 35 volar Barton fractures - No need for routine decompression of the median nerve

35 patients with volar Barton fractures were treated operatively from 1985-1994. The injury was due to a high velocity motor vehicle accident in 20 patients. All fractures were closed without major carpal injuries. 11 fractures were type B3.1, 21 type B3.2 and 3 type B3.3, according to the AO classification. All fractures were openly reduced and internally fixated by small buttress plates and screws. In 31 cases, the median nerve was unaffected by the injury and was not explored or decompressed during surgery. The patients were assessed clinically and radiographically after mean 6 (2-10) years. According to the criteria of Pattee and Thompson (1988), 23 patients had excellent results, 10 good and 2 fair. Posttraumatic arthrosis was found in 12 patients and was related to the congruency of the articular surface achieved at surgery. We conclude that the median nerve, when not damaged or compressed, should not be explored or decompressed during surgery

The fracture stress of rat achilles tendons

For the determination of the fracture stress of soft tissues both the fracture force and the cross sectional  area are required. For short tissues these prerequisites are difficult experimental tasks. The determination  of the fracture force necessitates proper gripping without damaging the tissues or altering their properties.  In order to meet this challenge the rapid-freezing technique was employed, modified to ensure that the  tendon was not frozen. On the other hand an accurate value of the cross sectional area of short soft tissues  is difficult to be obtained using conventional techniques. In this context a novel procedure is proposed here  based on the histologically-measured cross-sectional area of the dehydrated tendon after the biomechanical  testing. Combination of these solutions permitted the performance of tension tests for rat Achilles tendons  and calculation of their fracture stress. The values of the Achilles tendon failure stress, as estimated above,  exhibited considerably lower scattering compared to those of the fracture forces.

The significance of rotation in fracture-separation of the articular pillar of a lower cervical vertebra - A clinical and cadaveric study

We report 13 fracture-separations of an articular pillar at the lower cervical spine in 12 patients. There were 9 men and 3 women with a mean age at injury of 32 years, with involvement of C4, C5 and C6 vertebrae. Neurological symptoms were present in 9 patients, 2 were classified as ASIA A and 7 as ASIA D. The average magnitude of rotation of the articular pillar was 24 degrees (10 degrees-36 degrees). 4 patients with neurologic deficit and a rotated articular pillar of more than 25 degrees were operated on, while 8 patients, 3 of which had a rotation of more than 25 degrees, had closed treatment. Patients were followed from 8 months to 15 years (mean 9 years). Patients who had closed treatment and/or with a rotated fractured articular pillar of more than 25 degrees had less satisfactory results. This observation was affirmed by cadaveric studies which showed that rotation of more than 25 degrees is an additional factor of instability in a fractured articular pillar