Publications by authors named "Andreas Stark"

The compressive deformation of the extruded binary Mg-Gd with gadolinium in solid solution has been studied in situ by combining synchrotron diffraction and acoustic emission techniques during compression tests. These two techniques are useful in investigating the evolution of twinning in all its stages. The extruded bars develop a fiber texture with the basal plane parallel to the extrusion direction.

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Tactile sensation and vision are often both utilized for the exploration of objects that are within reach though it is not known whether or how these two distinct sensory systems combine such information. Here in mice, we used a combination of stereo photogrammetry for 3D reconstruction of the whisker array, brain-wide anatomical tracing and functional connectivity analysis to explore the possibility of tacto-visual convergence in sensory space and within the circuitry of the primary visual cortex (VISp). Strikingly, we find that stimulation of the contralateral whisker array suppresses visually evoked activity in a tacto-visual sub-region of VISp whose visual space representation closely overlaps with the whisker search space.

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The grain size is a determinant microstructural feature to enable the activation of deformation twinning in hexagonal close-packed (hcp) metals. Although deformation twinning is one of the most effective mechanisms for improving the strength-ductility trade-off of structural alloys, its activation is reduced with decreasing grain size. This work reports the discovery of the activation of deformation twinning in a fine-grained hcp microstructure by introducing ductile body-centered cubic (bcc) nano-layer interfaces.

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Precipitation hardened and tempered martensitic-ferritic steels (TMFSs) are used in many areas of our daily lives as tools, components in power generation industries, or in the oil and gas (O&G) industry for creep and corrosion resistance. In addition to the metallurgical and forging processes, the unique properties of the materials in service are determined by the quality heat treatment (HT). By performing a quenching and partitioning HT during an in situ high energy synchrotron radiation experiment in a dilatometer, the evolution of retained austenite, martensite laths, dislocations, and carbides was characterized in detail.

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Intermetallic γ-TiAl-based alloys are lightweight materials for high-temperature applications, e.g., in the aerospace and automotive industries.

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Background and purpose - Classification of ankle fractures is crucial for guiding treatment but advanced classifications such as the AO Foundation/Orthopedic Trauma Association (AO/OTA) are often too complex for human observers to learn and use. We have therefore investigated whether an automated algorithm that uses deep learning can learn to classify radiographs according to the new AO/OTA 2018 standards.Method - We trained a neural network based on the ResNet architecture on 4,941 radiographic ankle examinations.

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Eucoryphus Mik is a Palaearctic genus of Dolichopodidae, previously with two described species confined to the montane and alpine zones of the European Alps. This paper describes a third species, Eucoryphus piscariviverus sp. nov.

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In situ dilatometry experiments using high energy synchrotron X-ray diffraction in transmission mode were carried out at the high energy material science beamline P07@PETRAIII at DESY (Deutsches Elektronen Synchrotron) for the tempering steel AISI 4140 at defined mechanical loading. The focus of this study was on the initial tempering state ( f e r r i t e ) and the hardened state ( m a r t e n s i t e ). Lattice strains were calculated from the 2D diffraction data for different h k l planes and from those temperature-dependent lattice plane specific diffraction elastic constants ( D E C s ) were determined.

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Introduction: Hip fracture is common in the elderly and is associated with high comorbidity, mortality and complication rates. There has been an increase in the investigation of healthcare-related adverse events (AEs) in some patient groups but there is limited knowledge about hip fracture patients. The aim was to explore the incidence, preventability and nature of AEs in hip fracture patients.

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The aim of this work is to investigate quench induced precipitation during continuous cooling in aluminium wrought alloys EN AW-7150 and EN AW-6082 using in situ synchrotron wide-angle X-ray scattering (WAXS). While X-ray diffraction is usually an ex situ method, a variety of diffraction patterns were recorded during the cooling process, allowing in situ analysis of the precipitation process. The high beam energy of about 100 keV allows the beam to penetrate a bulk sample with a 4 mm diameter in a quenching dilatometer.

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In situ synchrotron radiation diffraction was performed during the compression of as-cast Mg-3Nd-Zn alloys with different amounts (0, 0.5, 1, and 2 wt %) of Zn addition at room temperature. During the tests, the acoustic emission signals of the samples were recorded.

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Nature uses self-assembly of a fairly limited selection of components to build hard and tough protective tissues like nacre and enamel. The resulting hierarchical micro/nanostructures provide decisive toughening mechanisms while preserving strength. However, to mimic microstructural and mechanical characteristics of natural materials in application-relevant synthetic nanostructures has proven to be difficult.

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In this study, new multilayer TiAl-based composites were developed and characterized. The materials were produced by spark plasma sintering (SPS) of elemental Ti and Al foils and ceramic particles (TiB₂ and TiC) at 1250 °C. The matrix of the composites consisted of α₂-TiAl and γ-TiAl lamellas and reinforcing ceramic layers.

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Background: Patients with surgically treated osteoarthritis of the hip have an increased risk of cardiovascular morbidity and mortality many years after the operation compared with controls. Our hypothesis is that this increased risk after total hip arthroplasty (THA) is mediated by development of periprosthetic osteolysis leading to aseptic loosening of the implant.

Methods: We conducted a nation-wide, nested, case-control study consisting of patients receiving a cemented THA due to osteoarthritis between the years 1992 and 2005.

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Recently, a species of was collected in Greece that differs morphologically from the European species commonly presumed to be (Scopoli, 1763). Verification of the identity of the Greek species through comparison with 460 specimens of from 17 West Palaearctic and one Afrotropical country, and examination of existing type material, revealed that the species recognized as in northwestern Europe for over 250 years is actually (Becker, 1907), the other known species in the genus, which was originally described from Tunisia. Although the types of have been lost, a comparison of the distribution ranges of both species in Europe provided evidence that the species collected in Greece is conspecific with .

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Mg-4Nd base alloys with Zn additions of 3, 5 and 8 wt % were investigated with in situ synchrotron radiation diffraction during solidification. This method enabled the investigation of phase formation and transformation in the alloys. The diffraction results were supported with TEM observations on the as-solidified samples.

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Metal-based additive manufacturing (AM) permits layer-by-layer fabrication of near net-shaped metallic components with complex geometries not achievable using the design constraints of traditional manufacturing. Production savings of titanium-based components by AM are estimated up to 50% owing to the current exorbitant loss of material during machining. Nowadays, most of the titanium alloys for AM are based on conventional compositions still tailored to conventional manufacturing not considering the directional thermal gradient that provokes epitaxial growth during AM.

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The mechanical properties of as-cast Mg-4Nd-xZn (x = 0, 3, 5 or 8 wt.%) alloys were investigated both in situ and ex situ in as-cast and solution-treated conditions. The additions of 3 or 5 wt.

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Objectives: To explore the value of simulation modelling in evaluating the effects of strategies to plan and schedule operating room (OR) resources aimed at reducing time to surgery for non-elective orthopaedic inpatients at a Swedish hospital.

Methods: We applied discrete-event simulation modelling. The model was populated with real world data from a university hospital with a strong focus on reducing waiting time to surgery for patients with hip fracture.

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Medulloblastoma, astrocytoma, and ependymoma represent the most common infratentorial tumors in childhood, while Ewing sarcomas in that localization are extremely rare. A large left infratentorial space-occupying lesion was diagnosed in a 12-year-old girl with signs of increased intracranial pressure. Following total tumor resection, histological and molecular examination revealed Ewing sarcoma with rearranged EWSR-1 gene.

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Objectives: Methylated O6-methylguanin-DNA-methytransferase (MGMT) promoter methylation is associated with survival in patients with glioblastoma. Current evidence suggests that further mismatch repair genes play a pivotal role in the tumor response to treatment. Candidate genes are MLH1, MSH2, and MSH6.

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Background: To date, information about the use of intraoperative MRI (iMRI) in patients undergoing neuroendoscopic procedures is sparse. The benefit may be (re)definition of neuronavigation, confirmation of fenestrations and biopsies, detection of complications, and redefinition of anatomical changes during the operation.

Material And Methods: Our setting consists of a fully integrated high-field 1.

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Article Synopsis
  • The study aimed to evaluate the effectiveness of temozolomide, a chemotherapy drug, in preventing brain metastases caused by breast cancer in mouse models.
  • Results showed that temozolomide successfully prevented brain metastases in cells without the O(6)-methylguanine-DNA methyltransferase (MGMT) protein, but was ineffective in MGMT-expressing cells.
  • The findings suggest that temozolomide's efficacy may depend on MGMT levels, highlighting the need for clinical research to explore its potential use in breast cancer patients with brain metastases.
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