Current Management of Diaphyseal Long Bone Defects-A Multidisciplinary and International Perspective.

The treatment of defects of the long bones remains one of the biggest challenges in trauma and orthopedic surgery. The treatment path is usually very wearing for the patient, the patient's environment and the treating physician. The clinical or regional circumstances, the defect etiology and the patient´s condition and mental status define the treatment path chosen by the treating surgeon. Depending on the patient´s demands, the bony reconstruction has to be taken into consideration at a defect size of 2-3 cm, especially in the lower limbs. Below this defect size, acute shortening or bone grafting is usually preferred. A thorough assessment of the patient´s condition including comorbidities in a multidisciplinary manner and her or his personal demands must be taken into consideration. Several techniques are available to restore continuity of the long bone. In general, these techniques can be divided into repair techniques and reconstructive techniques. The aim of the repair techniques is anatomical restoration of the bone with differentiation of the cortex and marrow. Currently, classic, hybrid or all-internal distraction devices are technical options. However, they are all based on distraction osteogenesis. Reconstructive techniques restore long-bone continuity by replacing the defect zone with autologous bone, e.g., with a vascularized bone graft or with the technique described by Masquelet. Allografts for defect reconstruction in long bones might also be described as possible options. Due to limited access to allografts in many countries and the authors' opinion that allografts result in poorer outcomes, this review focuses on autologous techniques and gives an internationally aligned overview of the current concepts in repair or reconstruction techniques of segmental long-bone defects.

Revealing the dynamics of ultrarelativistic non-equilibrium many-electron systems with phase space tomography.

The description of physical processes with many-particle systems is a key approach to the modeling of numerous physical systems. For example in storage rings, where ultrarelativistic particles are agglomerated in dense bunches, the modeling and measurement of their phase-space distribution is of paramount importance: at any time the phase-space distribution not only determines the complete space-time evolution but also provides fundamental performance characteristics for storage ring operation. Here, we demonstrate a non-destructive tomographic imaging technique for the 2D longitudinal phase-space distribution of ultrarelativistic electron bunches. For this purpose, we utilize a unique setup, which streams turn-by-turn near-field measurements of bunch profiles at MHz repetition rates. To demonstrate the feasibility of our method, we induce a non-equilibrium state and show that the phase-space distribution microstructuring as well as the phase-space distribution dynamics can be observed in great detail. Our approach offers a pathway to control ultrashort bunches and supports, as one example, the development of compact accelerators with low energy footprints.

Phase Diversity Electro-optic Sampling: A new approach to single-shot terahertz waveform recording.

Recording electric field evolution in single-shot with THz bandwidth is needed in science including spectroscopy, plasmas, biology, chemistry, Free-Electron Lasers, accelerators, and material inspection. However, the potential application range depends on the possibility to achieve sub-picosecond resolution over a long time window, which is a largely open problem for single-shot techniques. To solve this problem, we present a new conceptual approach for the so-called spectral decoding technique, where a chirped laser pulse interacts with a THz signal in a Pockels crystal, and is analyzed using a grating optical spectrum analyzer. By borrowing mathematical concepts from photonic time stretch theory and radio-frequency communication, we deduce a novel dual-output electro-optic sampling system, for which the input THz signal can be numerically retrieved-with unprecedented resolution-using the so-called phase diversity technique. We show numerically and experimentally that this approach enables the recording of THz waveforms in single-shot over much longer durations and/or higher bandwidth than previous spectral decoding techniques. We present and test the proposed DEOS (Diversity Electro-Optic Sampling) design for recording 1.5 THz bandwidth THz pulses, over 20 ps duration, in single-shot. Then we demonstrate the potential of DEOS in accelerator physics by recording, in two successive shots, the shape of 200 fs RMS relativistic electron bunches at European X-FEL, over 10 ps recording windows. The designs presented here can be used directly for accelerator diagnostics, characterization of THz sources, and single-shot Time-Domain Spectroscopy.

Deriving x-ray pulse duration from center-of-energy shifts in THz-streaked ionized electron spectra.

A fast and robust, yet simple, method has been developed for the immediate characterization of x-ray pulse durations via IR/THz streaking that uses the center of energy (COE) of the photoelectron spectrum for the evaluation. The manuscript presents theory and numerical models demonstrating that the maximum COEs shift as a function of the pulse duration and compares them to existing data for validation. It further establishes that the maximum COE can be derived from two COE measurements set at a phase of π/2 apart. The theory, model, and data agree with each other very well, and they present a way to measure pulse durations ranging from sub-fs to tens of fs on-the-fly with a fairly simple experimental setup.

Linear array detector for online diagnostics of spectral distributions at MHz repetition rates.

Free-electron lasers (FELs) based on superconducting accelerator technology and storage ring facilities operate with bunch repetition rates in the MHz range, and the need arises for bunch-by-bunch electron and photon diagnostics. For photon-pulse-resolved measurements of spectral distributions, fast one-dimensional profile monitors are required. The linear array detector KALYPSO (KArlsruhe Linear arraY detector for MHz-rePetition rate SpectrOscopy) has been developed for electron bunch or photon pulse synchronous read-out with frame rates of up to 2.7 MHz. At the FLASH facility at DESY, a current version of KALYPSO with 256 pixels has been installed at a grating spectrometer as online diagnostics to monitor the pulse-resolved spectra of the high-repetition-rate FEL pulses. Application-specific front-end electronics based on MicroTCA standard have been developed for data acquisition and processing. Continuous data read-out with low latency in the microsecond range enables the integration into fast feedback applications. In this paper, pulse-resolved FEL spectra recorded at 1.0 MHz repetition rate for various operation conditions at FLASH are presented, and the first application of an adaptive feedback for accelerator control based on photon beam diagnostics is demonstrated.