Hierarchy measurement for modeling network dynamics under directed attacks.

A fundamental issue in the dynamics of complex systems is the resilience of the network in response to targeted attacks. This paper explores the local dynamics of the network attack process by investigating the order of removal of the nodes that have maximal degree, and shows that this dynamic network response can be predicted from the graph's initial connectivity. We demonstrate numerically that the maximal degree M(τ) of the network at time step τ decays exponentially with τ via a topology-dependent exponent. Moreover, the order in which sites are removed can be approximated by considering the network's "hierarchy" function h, which measures for each node V_{i} how many of its initial nearest neighbors have lower degree versus those that have a higher one. Finally, we show that the exponents we identified for the attack dynamics are related to the exponential behavior of spreading activation dynamics. The results suggest that the function h, which has both local and global properties, is a novel nodal measurement for network dynamics and structure.

[Complications in surgical management of spinal injuries]. / Komplikationen bei der operativen Versorgung von Wirbelsäulenverletzungen.

Operative treatment of spinal injuries requires an accurate surgical technique and biochemical know-how to avoid complications due to mistakes in device handling, operative technique, and indication. Device failures are caused by loosening of locking clamps or fracture of Schanz screws, followed by loss of angle stability and early loss of reduction. Maldisplacement of pedicle screws may involve irritation of neurovascular structures or loss of correction as well as insufficient transpedicular bone reduction and bone grafting. In burst fractures with destruction of the vertebral body and loose canal fragments, the posterior approach is less efficient than a combined procedure.

[Open fractures of the elbow joint]. / Offene Frakturen des Ellbogengelenkes.

Both in open and in closed elbow fractures, anatomical joint reconstruction and rigid internal fixation, which permit early initiation of motion, are essential for good joint function. However, in open distal intraarticular humerus fractures this is more difficult to achieve, owing to the high rate of comminuted types C 2 and C 3 fractures. In addition, the extensive soft tissue lesions often mean that physiotherapy cannot be started until later than would otherwise be desirable. This retrospective study shows that the functional results in 60 patients operated on for correction of open distal intraarticular humerus fractures were worse (1/3 "excellent/good", 2/3 "moderate/poor") than those in patients treated for closed fractures. Complications included superficial infection in 7 patients, osteitis in 11, late instability in 10, fatigue failure of the implants in 5, and non-union in 10 patients.

[Operative treatment of distal intra-articular humerus fractures; results of 412 follow-up cases (AO-collected statistics)]. / Die operative Behandlung von distalen intraarticulären Humerusfrakturen; Ergebnis von 412 nachkontrollierten Fällen (AO-Sammelstatistik).

Intraarticular fractures require a surgical therapy. The functional results are depending on the anatomical reconstruction of the joint surfaces and on early kinesitherapy. Remaining disabilities may be controlled in 2/3 of the cases to such an extent that no alterations are necessary in private or professional life. The overall result was very good in 23.8%, good in 36.0%, moderate in 22.3% and bad in 17.9%. These bad results are due to the rate of polytraumatized patients (18%) and the high rate of open comminuted fractures (27%).