0000000000037706
AUTHOR
Michael Schneider
showing 21 related works from this author
Routing electric vehicles with a single recharge per route
2020
Networks : an international journal (2020). doi:10.1002/net.21964
Incidence of heterotopic ossification in minimally invasive short-stem THA using the modified anterolateral approach.
2017
Introduction Heterotopic ossification (HO) is known to be a common complication after total hip arthroplasty (THA). The minimal invasive (MIS) modified anterolateral approach has become popular in combination with a short stem. We analysed the incidence of HO following short-stem THA using this approach in combination with a postoperative administration of nonsteroidal anti-inflammatory drugs (NSAIDs). Materials and methods 216 short stems were implanted in 162 patients. NSAIDs were administered for 2 weeks after surgery in 154 patients (95.1%). Standardised pre- and postoperative radiographic imaging was done at 2-year follow-up. HO was analysed according to the Brooker classification. Inf…
Evidence of 200 TeV photons from HAWC J1825-134
2020
The Earth is bombarded by ultra-relativistic particles, known as cosmic rays (CRs). CRs with energies up to a few PeV (=10$^{15}$ eV), the knee in the particle spectrum, are believed to have a Galactic origin. One or more factories of PeV CRs, or PeVatrons, must thus be active within our Galaxy. The direct detection of PeV protons from their sources is not possible since they are deflected in the Galactic magnetic fields. Hundred TeV $\gamma$-rays from decaying $\pi^0$, produced when PeV CRs collide with the ambient gas, can provide the decisive evidence of proton acceleration up to the knee. Here we report the discovery by the High Altitude Water Cherenkov (HAWC) observatory of the $\gamma…
Automatable sample fabrication process for pump-probe X-ray holographic imaging
2014
Soft X-ray holography is a recently developed imaging technique with sub-50 nm spatial resolution. Key advantages of this technique are magnetic and elemental sensitivity, compatibility with imaging at free electron laser facilities, and immunity to in-situ sample excitations and sample drift, which enables the reliable detection of relative changes between two images with a precision of a few nanometers. In X-ray holography, the main part of the experimental setup is integrated in the sample, which consequently requires a large number of fabrication steps. Here we present a generic design and an automatable fabrication process for samples suitable, and optimized for, efficient high resolut…
Ultrafast Dynamics of Magnetic Domain Structures Probed by Coherent Free-Electron Laser Light
2013
Synchrotron radiation news 26(6), 27 - 32 (2013). doi:10.1080/08940886.2013.850384
Secondary Osseous Integration of Cementless Unicompartmental Knee Arthroplasty After Internal Fixation of a Felix Type IIIB Fracture
2021
Case A 76-year-old man presented with periprosthetic tibial plateau fracture (TPF), with a completely loosened tibial component 3 weeks after cementless unicompartmental knee arthroplasty (UKA). Internal fixation by buttress plating was performed, and the tibial component was retained and left in situ primarily as a spacer. Revision was planned after fracture consolidation, but at 3 months, the patient was able to walk without support, without pain, and with full range of motion. At 1 year, he is free of complaints. The initial loosened tibial component reintegrated. Conclusion Internal fixation combined with preserving the loosened tibial component may be a treatment option for TPF involvi…
Design and performance of the prototype Schwarzschild-Couder telescope camera
2022
Journal of astronomical telescopes, instruments, and systems 8(01), 014007-1 (2022). doi:10.1117/1.JATIS.8.1.014007
Advances in vehicle routing and logistics optimization
2019
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Monolithic focused reference beam x-ray holography
2013
Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot imaging at coherent X-ray sources. In its common implementation, the image contrast is limited by the reference signal generated by a small pinhole aperture. Increased pinhole diameters improve the signal, whereas the resolution is diminished. Here we report a new concept to decouple the spatial resolution from the image contrast by employing a Fresnel zone plate to provide the reference beam. Superimposed on-axis images of distinct foci are separated with a novel algorithm. Our method is insensitive to mechanical drift or vibrations and allows for long integration times common at low-flux…
Evidence that Ultra-High-Energy Gamma Rays are a Universal Feature Near Powerful Pulsars
2021
The highest-energy known gamma-ray sources are all located within 0.5 degrees of extremely powerful pulsars. This raises the question of whether ultra-high-energy (UHE; $>$ 56 TeV) gamma-ray emission is a universal feature expected near pulsars with a high spin-down power. Using four years of data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, we present a joint-likelihood analysis of ten extremely powerful pulsars to search for UHE gamma-ray emission correlated with these locations. We report a significant detection ($>$ 3$��$), indicating that UHE gamma-ray emission is a generic feature of powerful pulsars. We discuss the emission mechanisms of the gamma rays a…
Dynamics and inertia of skyrmionic spin structures
2015
Understanding the motion of magnetic skyrmions is essential if they are to be used as information carriers in devices. It is now shown that topological confinement endows the skyrmions with an unexpectedly large mass, which plays a key role in their dynamics.
Dynamics and topological mass of skyrmionic spin structures (presentation video)
2014
Skyrmions are topologically protected particle-like configurations, with a topological complexity described by their Skyrmion number. In magnetic systems, they have been numerically predicted to exhibit rich dynamics, such as the gyrotropic and breathing modes, dominated by their topology. Recent experimental advances brought their static manipulation well under control. However, their dynamical behaviour is largely unexplored experimentally. In this work, we provide with the first direct observation of eigenmode skyrmion dynamics. In particular, we present dynamical imaging data with high temporal and spatial resolution to demonstrate the GHz gyrotropic mode of a single skyrmion bubble, as…
A survey of active galaxies at TeV photon energies with the HAWC gamma-ray observatory
2020
The High Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) continuously detects TeV photons and particles within its large field-of-view, accumulating every day a deeper exposure of two thirds of the sky. We analyzed 1523~days of HAWC live data acquired over four and a half years, in a follow-up analysis of {138} nearby ($z<0.3$) active galactic nuclei from the {\em Fermi} 3FHL catalog culminating within $40^\circ$ of the zenith at Sierra Negra, the HAWC site. This search for persistent TeV emission used a maximum-likelihood analysis assuming intrinsic power-law spectra attenuated by pair production of gamma-ray photons with the extragalactic background light. HAWC clearly detects persi…
Publication Network Analysis of an Academic Family in Information Systems
2011
The study of scientific collaboration through network analysis can give interesting conclusions about the publication habits of a scientific community. Co-authorship networks represent scientific collaboration as a graph: nodes correspond to authors, edges between nodes mark joint publications (Newman 2001a,b). Scientific publishing is decentralized. Choices of co-authors and research topics are seldomly globally coordinated. Still, the structure of co-authorship networks is far from random. Co-authorship networks are governed by principles that are similar in other complex networks such as social networks (Wasserman and Faust 1994), networks of citations between scientific papers (Egghe an…
HAWC J2227+610 and its association with G106.3+2.7, a new potential Galactic PeVatron
2020
We present the detection of VHE gamma-ray emission above 100 TeV from HAWC J2227+610 with the HAWC observatory. Combining our observations with previously published results by VERITAS, we interpret the gamma-ray emission from HAWC J2227+610 as emission from protons with a lower limit in their cutoff energy of 800 TeV. The most likely source of the protons is the associated supernova remnant G106.3+2.7, making it a good candidate for a Galactic PeVatron. However, a purely leptonic origin of the observed emission cannot be excluded at this time.
3HWC: The Third HAWC Catalog of Very-High-Energy Gamma-ray Sources
2020
We present a new catalog of TeV gamma-ray sources using 1523 days of data from the High Altitude Water Cherenkov (HAWC) observatory. The catalog represents the most sensitive survey of the Northern gamma-ray sky at energies above several TeV, with three times the exposure compared to the previous HAWC catalog, 2HWC. We report 65 sources detected at $\geq$ 5 sigma significance, along with the positions and spectral fits for each source. The catalog contains eight sources that have no counterpart in the 2HWC catalog, but are within $1^\circ$ of previously detected TeV emitters, and twenty sources that are more than $1^\circ$ away from any previously detected TeV source. Of these twenty new so…
Return to Sports and Recreational Activity After Single-Stage Bilateral Short-Stem Total Hip Arthroplasty: 5-Year Results of a Prospective Observatio…
2019
Background:Single-stage bilateral total hip arthroplasty (THA) is an alternative to staged unilateral THA in patients suffering from bilateral hip arthritis; however, there is still broad concern regarding the safety and reliability of this procedure. Short-stem THA has emerged in recent years. To date, no data are available on sports and recreational activity levels after single-stage bilateral short-stem THA in the general patient population.Hypothesis:Patients who have undergone single-stage bilateral short-stem THA return to a satisfying level of sports and recreational activity at midterm follow-up.Study Design:Case series; Level of evidence, 4.Methods:A total of 54 consecutive patient…
Upper and lower bounds for the vehicle-routing problem with private fleet and common carrier
2019
Abstract The vehicle-routing problem with private fleet and common carrier (VRPPC) extends the capacitated VRP by considering the option of outsourcing customers to subcontractors at a customer-dependent cost instead of serving them with the private fleet. The VRPPC has important applications in small package shipping and manufacturing, but despite its relevance, no exact solution approach has been introduced so far. We propose a branch-price-and-cut algorithm that is able to solve small to medium-sized instances and provides tight lower bounds for larger instances from the literature. In addition, we develop a large neighborhood search that shows a decent solution quality and competitive r…
Urine tropenol ester levels in workers handling tiotropium bromide synthesis: implications for exposure prevention and biomonitoring
2019
Tropenol ester is a highly toxic anticholinergic substance and an intermediate used in industrial production of the bronchodilator tiotropium bromide. The aim of this study was to systematically test workers involved in its production for tropenol ester in urine to identify any exposure pathways and define additional preventive measures. Twelve workers performing tasks involving potential exposure to tropenol ester were repeatedly monitored at the end of each production cycle. Medical exams revealed no symptoms of acute poisoning with tropenol ester, but biological monitoring of urine showed 36 positive findings in 79 samples, with tropenol ester concentrations ranging between the detection…
A survey of variants and extensions of the location-routing problem
2015
This is a review of the literature on variants and extensions of the standard location-routing problem published since the last survey, by Nagy and Salhi, appeared in 2006. We propose a classification of problem variants, provide concise paper excerpts that convey the central ideas of each work, discuss recent developments in the field, and list promising topics for further research.
A problem-adjusted genetic algorithm for flexibility design
2013
Many present markets for goods and services have highly volatile demand due to short life cycles and strong competition in saturated environments. Determination of capacity levels is difficult because capacities often need to be set long before demand realizes. In order to avoid capacity-demand mismatches, operations managers employ mix-flexible resources which allow them to shift excess demands to unused capacities. The Flexibility Design Problem (FDP) models the decision on the optimal configuration of a flexible (manufacturing) network. FDP is a difficult stochastic optimization problem, for which traditional exact approaches are not able to solve but the smallest instances in reasonable…