Analysis of passively combined divided-pulse amplification as an energy-scaling concept

The energy scaling of ultrashort-pulse systems employing simultaneously the techniques of chirped-pulse amplification and passively combined divided-pulse amplification is analyzed both experimentally and numerically. The maximum achievable efficiency is investigated and fundamental limitations originating from gain saturation, self-phase modulation and depolarization are discussed. A solution to these limitations could be an active stabilization scheme, which would allow for the operation of every single fiber amplifier at higher pulse energies

Visual Analysis for Hospital Infection Control using a RNN Model

Bacteria and viruses are transmitted among patients in the hospital. Infection control experts develop strategies for infection control. Currently, this is done mostly manually, which is time-consuming and error-prone. Visual analysis approaches mainly focus disease spread on population level.We learn a RNN model for detection of potential infections, transmissions and infection factors. We present a novel interactive visual interface to explore the model results. Together with infection control experts, we apply our approach to real hospital data. The experts could identify factors for infections and derive infection control measures

Fiber-based source for multiplex-CARS microscopy based on degenerate four-wave mixing

We present a fiber-based laser source for multiplex coherent anti-Stokes Raman scattering (CARS) microscopy. This source is very compact and potentially alignment-free. The corresponding pump and Stokes pulses for the CARS process are generated by degenerate four-wave mixing (FWM) in photonic-crystal fibers. In addition, an ytterbium-doped fiber laser emitting spectrally narrow 100 ps pulses at 1035 nm wavelength serves as pump for the FWM frequency conversion. The FWM process delivers narrow-band pulses at 648 nm and drives a continuum-like spectrum ranging from 700 to 820 nm. With the presented source vibrational resonances with energies between 1200 cm-1 and 3200 cm-1 can be accessed with a resolution of 10 cm-1. Additionally, the temporal characteristics of the FWM output have been investigated by a cross-correlation setup, revealing the suitability of the emitted pulses for CARS microscopy. This work marks a significant step towards a simple and powerful all-fiber, maintenance-free multiplex-CARS source for real-world applications outside a laboratory environment

The need for digitalisation in electroplating – How digital approaches can help to optimize the electrodeposition of chromium from trivalent electrolytes

In order to make material design processes more efficient in the future, the underlying multidimensional process parameter spaces must be systematically explored using digitalisation techniques such as machine learning (ML) and digital simulation. In this paper we shortly review essential concepts for the digitalisation of electrodeposition processes with a special focus on chromium plating from trivalent electrolytes

All-fiber laser source for CARS microscopy based on fiber optical parametric frequency conversion

A novel approach for an all-fiber mono-laser source for CARS microscopy is presented. An Yb-fiber laser generates 100 ps pulses, which later undergo narrowband in-fiber frequency conversion based on degenerate four-wave-mixing. The frequency conversion is optimized to access frequency shifts between 900 and 3200cm-1, relevant for vibrational imaging. Inherently synchronized pump and Stokes pulses are available at one fiber end, readily overlapped in space and time. The source is applied to CARS spectroscopy and microscopy experiments in the CH-stretching region around 3000cm-1. Due to its simplicity and maintenance-free operation, the laser scheme holds great potential for bio-medical applications outside laser laboratories

In situ oxygen utilization in the rat intervertebral disc

Nucleus pulposus cells of the intervertebral disc have no endogenous vasculature and have thus been hypothesized to be hypoxic. This hypothesis was tested using 2-nitroimidazole, EF5, a drug that at low oxygen concentrations forms covalent adducts with cellular proteins. After administrating EF5 to rats, sections of the intervertebral disc were analysed for EF5 adducts. Drug adducts were quantified in tissue sections using a fluorescent monoclonal antibody. Although the level of EF5 fluorescence in all intervertebral disc tissues was low, the transition zone at the periphery of the nucleus pulposus exhibited the highest level of EF5 binding. To substantiate this result, tissue nitroreductase levels and drug pharmacology were evaluated. Nitroreductase levels were measured in whole discs under severe hypoxia. We noted that there was robust EF5 binding to cells in the annulus fibrosus and transition zone with modest binding to cells of the nucleus pulposus and endplate. High-performance liquid chromatography analysis indicated limitations in EF5 access to the nucleus pulposus, most probably related to the lack of vasculature and slow drug distribution through the gel-like interior of the disc. However, despite diffusion problems, the drug dose was determined to be sufficient to report the oxygen status of the nucleus pulposus cells. Based on these findings, we conclude that despite poor vascularization, the disc cells accommodate to the local environment by displaying a limited need for oxygen. Accordingly, the cells of the intervertebral disc are not severely hypoxic

DROPS -- OS Support for Distributed Multimedia Applications

The characterising new requirement for distributed multimedia applications is the coexistence of dynamic real-time and non-real-time applications on hosts and networks. While some networks (e.g., ATM) in principle have the capability to reserve bandwidth on shared links, host systems usually do not. DROPS (Dresden Real-time OPerating System) is being built to remedy that situation by providing resource managers that allow the reservation of resources in advance and enforce that reservations. It allows the coexistence of timesharing applications (with no reservations) and real-time applications (with reservations). By outlining the principle architecture, some design decisions, and first results, the paper demonstrates how these objectives can be met using straightforward OS technology. It argues that middleware for diverse platforms cannot meet these objectives efficiently without proper core operating system support