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Ice shelves play a key role in the stability of the Antarctic Ice Sheet due to their buttressing effect. A loss of buttressing as a result of increased basal melting or ice shelf disintegration will lead to increased ice discharge. Some ice shelves exhibit channels at the base that are not yet fully understood. In this study, we present in situ melt rates of a channel which is up to 330 m high and located in the southern Filchner Ice Shelf. Maximum observed melt rates are 2 m yr−1. Melt rates inside the channel decrease in the direction of ice flow and turn to freezing ∼55 km downstream of the grounding line. While closer to the grounding line melt rates are higher within the channel than outside, this relationship reverses further downstream. Comparing the modeled evolution of this channel under present-day climate conditions over 250 years with its present geometry reveals a mismatch. Melt rates twice as large as the present-day values are required to fit the observed geometry. In contrast, forcing the model with present-day melt rates results in a closure of the channel, which contradicts observations. The ice shelf experiences strong tidal variability in vertical strain rates at the measured site, and discrete pulses of increased melting occurred throughout the measurement period. The type of melt channel in this study diminishes in height with distance from the grounding line and is hence not a destabilizing factor for ice shelves.

Governance of interorganizational networks for joint project execution has become a popular research theme in recent years. However, little is known about how the knowledge in this field is structured and how to further develop it based on the given structure. This systematic literature review identifies three main categories of literature in this field: design of network governance, network performance, and theory in network governance. Each of these categories is further divided into subcategories, which are assessed for the timely development and current state of knowledge. This provides the foundation for the development of a research agenda, which includes configurational understanding of network governance design, governing for temporary organizing particularities, and level-crossing theoretical development.

In this work, two different approaches to treat boundary conditions in a lattice Boltzmann method (LBM) for the wave equation are presented. We interpret the wave equation as the governing equation of the displacement field of a solid under simplified deformation assumptions, but the algorithms are not limited to this interpretation. A feature of both algorithms is that the boundary does not need to conform with the discretization, i.e., the regular lattice. This allows for a larger flexibility regarding the geometries that can be handled by the LBM. The first algorithm aims at determining the missing distribution functions at boundary lattice points in such a way that a desired macroscopic boundary condition is fulfilled. The second algorithm is only available for Neumann-type boundary conditions and considers a balance of momentum for control volumes on the mesoscopic scale, i.e., at the scale of the lattice spacing. Numerical examples demonstrate that the new algorithms indeed improve the accuracy of the LBM compared to previous results and that they are able to model boundary conditions for complex geometries that do not conform with the lattice.

In this work, the particle finite element method (PFEM) is extended to simulate additive manufacturing processes in a variety of different complicated geometries. A three-dimensional α-shape approach is used to carry out the material addition procedure. It overcomes the limitation of merely employing the traditional element birth and death technique and reduces the degrees-of-freedom compared to this technique. Furthermore, numerical examples are used to evaluate and demonstrate the applicability of the PFEM method for additive manufacturing within the framework of a weakly coupled thermoelasticity formulation. During additive manufacturing operations, deflections, stresses, and temperature are computed using a user-defined implementation in FEniCS.

Recently, phase field modeling of fatigue fracture has gained a lot of attention from many researches and studies, since the fatigue damage of structures is a crucial issue in mechanical design. Differing from traditional phase field fracture models, our approach considers not only the elastic strain energy and crack surface energy, additionally, we introduce a fatigue energy contribution into the regularized energy density function caused by cyclic load. Comparing to other type of fracture phenomenon, fatigue damage occurs only after a large number of load cycles. It requires a large computing effort in a computer simulation. Furthermore, the choice of the cycle number increment is usually determined by a compromise between simulation time and accuracy. In this work, we propose an efficient phase field method for cyclic fatigue propagation that only requires moderate computational cost without sacrificing accuracy. We divide the entire fatigue fracture simulation into three stages and apply different cycle number increments in each damage stage. The basic concept of the algorithm is to associate the cycle number increment with the damage increment of each simulation iteration. Numerical examples show that our method can effectively predict the phenomenon of fatigue crack growth and reproduce fracture patterns.

Polycomb group (PcG) protein-mediated histone methylation (H3K27me3) controls the correct spatiotemporal expression of numerous developmental regulators in Arabidopsis. Epigenetic silencing of the stem cell factor gene WUSCHEL (WUS) in floral meristems (FMs) depends on H3K27me3 deposition by PcG proteins. However, the role of H3K27me3 in silencing of other meristematic regulator and pluripotency genes during FM determinacy has not yet been studied. To this end, we report the genome-wide dynamics of H3K27me3 levels during FM arrest and the consequences of strongly depleted PcG activity on early flower morphogenesis including enlarged and indeterminate FMs. Strong depletion of H3K27me3 levels results in misexpression of the FM identity gene AGL24, which partially causes floral reversion leading to ap1-like flowers and indeterminate FMs ectopically expressing WUS and SHOOT MERISTEMLESS (STM). Loss of STM can rescue supernumerary floral organs and FM indeterminacy in H3K27me3-deficient flowers, indicating that the hyperactivity of the FMs is at least partially a result of ectopic STM expression. Nonetheless, WUS remained essential for the FM activity. Our results demonstrate that PcG proteins promote FM determinacy at multiple levels of the floral gene regulatory network, silencing initially floral regulators such as AGL24 that promotes FM indeterminacy and, subsequently, meristematic pluripotency genes such as WUS and STM during FM arrest.

Background: Transcatheter aortic valve replacement is an established treatment option for patients with severe symptomatic aortic stenosis and is most commonly performed through the transfemoral access route. Percutaneous access site closure can be achieved using dedicated plug-based or suture-based vascular closure device (VCD) strategies, but randomized comparative studies are scarce. Methods: The CHOICE-CLOSURE trial (Randomized Comparison of Catheter-based Strategies for Interventional Access Site Closure during Transfemoral Transcatheter Aortic Valve Implantation) is an investigator-initiated, multicenter study, in which patients undergoing transfemoral transcatheter aortic valve replacement were randomly assigned to vascular access site closure using either a pure plug-based technique (MANTA, Teleflex) with no additional VCDs or a primary suture-based technique (ProGlide, Abbott Vascular) potentially complemented by a small plug. The primary end point consisted of access site– or access-related major and minor vascular complications during index hospitalization, defined according to the Valve Academic Research Consortium-2 criteria. Secondary end points included the rate of access site– or access-related bleeding, VCD failure, and time to hemostasis. Results: A total of 516 patients were included and randomly assigned. The mean age of the study population was 80.5±6.1 years, 55.4% were male, 7.6% of patients had peripheral vascular disease, and the mean Society of Thoracic Surgeons score was 4.1±2.9%. The primary end point occurred in 19.4% (50/258) of the pure plug-based group and 12.0% (31/258) of the primary suture-based group (relative risk, 1.61 [95% CI, 1.07–2.44], P =0.029). Access site– or access-related bleeding occurred in 11.6% versus 7.4% (relative risk, 1.58 [95%CI: 0.91–2.73], P =0.133) and device failure in 4.7% versus 5.4% (relative risk, 0.86, [95% CI, 0.40–1.82], P =0.841) in the respective groups. Time to hemostasis was significantly shorter in the pure plug-based group (80 [32–180] versus 240 [174–316] seconds, P Conclusions: Among patients treated with transfemoral transcatheter aortic valve replacement, a pure plug-based vascular closure technique using the MANTA VCD is associated with a higher rate of access site– or access-related vascular complications but a shorter time to hemostasis compared with a primary suture-based technique using the ProGlide VCD. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04459208.

Increasingly, scholars are recognising the importance of resilience in projects. However, there is a lack of research on the resilience of temporary inter-organisational projects while considering the intricate relationship among multiple stakeholder organisations. We conducted an embedded comparative case study to investigate the mechanisms how stakeholder relationships involving prior ties and inter-organisational governance in the project support its resilience. Our results show that few prior ties among stakeholders keep them vigilant, fostering the readiness and preparedness for resilience, while many prior ties keep social solidarity among stakeholders, fostering the response and recovery for resilience. Contractual and relational governance improves resilience by clarifying stakeholders’ roles and responsibilities and forming collective cognition, respectively. We believe a plural governance design based on prior ties among stakeholders will improve resilience of the inter-organisational project, by promoting dynamically distributed and centralised stakeholder engagement in preparing, responding and recovering from the unexpected.

In this paper we ask who is a legitimate agent of social change for Grand Challenges. To answer this question, we build on the philosophies of Hannah Arendt, Friedrich Nietzsche, Maurice Blanchot and Emmanuel Levinas on the human condition. This is important in sensitizing the project management community to the political responsibility of the project manager at times of crises and Grand Challenges, when new social orders, such as the Grand Challenges Approach (GCA), emerge and are delivered through projects. We introduce philosophers who have spoken about the human condition a) to escape definitions of legitimacy which have arisen from the very social processes and institutions which contribute to social injustices; and, b) because we all share the human condition irrespective of origin, religion, race, gender, education and life experiences, and as such it carries significant democratic potential. The philosophers tell us that an agent of social change is s/he who acts with the Other as the end goal in mind, and that legitimate is the social agent who appears in front of the watchful eye of society and fully discloses past, present and future intentions (Arendt); who can embody meaning and make decisions based on their humanity (Nietzsche); who can echo ideals which extend thought, intelligence, decisions and actions from what is already known to the creation of new spaces of action (Blanchot); and, finally, who can stand upright and engage with fellow-world-citizens in defining what is to be known, the reality of tomorrow (Levinas).

A constitutive model describing the deformation‐induced martensite transformation in metastable austenitic CrNi steels is presented. In line with the previous work of Stringfellow et al. [1], the material is considered to have a composite response of the underlying austenite and the evolving martensite phases. The stresses and strains in the individual phases are described using viscoplastic models. The effective properties of the material are then computed by a homogenization method. Strain hardening in the individual phases is represented using separate flow rules. Furthermore, based on the plastic strain in the austenitic phase, a transformation kinetics model describes the evolution of the martensite volume, in the two‐phase composite. A numerical implementation of the model is done in the finite element program FEAP [2]. The parameters in model are identified by experimental data using the least‐squares optimization. Finally, some results are presented using an illustrative boundary value problem of a structured surface.

Ice shelves are large floating ice masses, that are formed when glaciers are becoming afloat at the margin of ice sheets. One dominating mass loss mechanism of ice shelves is calving, describing the detachment of icebergs at the front. Ice shelves stabilize inland ice glaciers due to buttressing. If the stabilizing effect of an ice shelf vanishes because of disintegration or thinning, the corresponding glacier accelerates resulting in sea level rise. To describe calving and disintegration of ice shelves, it is important to investigate fracture propagation in ice. A powerful method in fracture mechanics is the phase field method which is based on Griffith's theory. It approximates cracks in a diffuse manner by using a continuous scalar field. We propose a phase field fracture model for ice considering its characteristic material properties. The material behavior of ice depends on the considered time scales. On short time scales it behaves like a solid and while it acts like a fluid on long time scales, which classifies it as a viscoelastic material of Maxwell type. This has been verified by observations. The phase field method allows us to simulate typical fracture situations of ice shelves in Antarctica and Greenland.

The complexity, internal and external risks, and significant social impact of megaprojects make their organizational resilience particularly important. To survive potential adversities, megaproject organizational resilience depends on collective mindfulness. Drawing on an attention-based view, this study investigates the mechanisms of collective mindfulness for megaproject organizational resilience as a process that functions prior to, during, and after recovery from crises. The results from analyzing six embedded crisis events in two megaprojects indicate that collective mindfulness influences organizational resilience processes through the mechanisms of awareness allocation, emotional detachment, and attention alignment. The study's theoretical and practical implications are discussed.

BackgroundDegenerative rotator cuff tears are common in elderly patients. However, the treatment strategies remain controversial. While physiotherapy can lead to pain relief and improved shoulder function, spontaneous tendon healing will not take place and, thus, non-operative management bears the risk of tear progression. Surgical management is the only way to restore the tendon-to-bone interface in spite of a considerable number of retears.MethodsThe present study reviewed the data provided by randomized controlled trials (RCTs) that have compared physiotherapy with surgical rotator cuff repair. Systematic reviews of this kind have been published before; however, this paper re-analyzes the data, given that Moosmayer et al. recently published an RCT with 10-year follow-up. Such long-term data are comparatively rare in the field of musculoskeletal surgery and therefore a reconsideration of treatment recommendations seems necessary.ResultsThe results show a mean difference in the Constant and Murley score of 6.2 points (95% confidence interval, 2.6; 9.7,P P ConclusionIn summary, this review shows superior clinical results for surgical repair of small- to medium-sized degenerative rotator cuff tears especially in the long term compared to physiotherapy.

Based on social comparison theory and organizational justice, this research explores how Guanxi with the horizontal leader (HL) influences coworker turnover intention. We used the snowball sampling method to collect survey data from 203 employees in 22 project teams. Overall, Guanxi with the HL had an indirect influence on turnover intention through perceived distributive justice pertaining to HL identification. Additionally, procedural justice had a negative, cross-level moderating effect on the relationship between Guanxi with the HL and perceived distributive justice. However, the individual-level moderating role of interactional justice was not supported. Theoretical and managerial implications of these findings are discussed.

Putting a mechanical structure under repeated cyclic loading can lead to fatigue crack initiation and propagation in materials. In engineering processes, a fatigue crack evolution behavior can be very complicated when the structure is in a complex environment. It has been shown that internal friction is one of the most important factors for the fatigue behavior of materials. However, there is still a lack of studies on how to predict the influences of internal friction on fatigue crack evolution. In this work, we show that the phase field model provides an elegant solution for structures under different loading frequencies and temperatures. Although the phase field fatigue model has been studied for years for mechanical loading situations, the question of how to include thermal fatigue effect remains open. In this work, we add thermal stresses to the phase field model as the second fatigue driving force. It is shown that the model is able to predict thermal fatigue behavior.

The largest floating tongue of Greenland’s ice sheet, Nioghalvfjerdsbrae, has so far been relatively stable with respect to areal retreat. Curiously, it experienced significant less thinning and ice flow acceleration than its neighbour Zacharias Isbrae. Draining more than 6% of the ice sheet, Nioghalvfjerdsbrae might become a large contributor to sea level rise in the future. Therefore, the stability of the floating tongue is a focus of this study. We employ a suite of observational methods to detect recent changes. We found that the calving style has changed at the southern part of the eastern calving front from normal tongue-type calving to a crack evolution initiated at frontal ice rises reaching 5-7km and progressing further upstream compared to 2010. The calving front area is further weakened by a substantial increase of a zone of fragments and open water at the tongue’s southern margin, leading to the formation of a narrow ice bridge. These geometric and mechanical changes are a precursor of instability of the floating tongue. We complement our study by numerical ice flow simulations to estimate the impact of future break-up or disintegration events on the ice discharge. These idealised scenarios reveal that a loss of the south-eastern area would lead to 1% of increase of ice discharge at the grounding line, while a sudden collapse of the frontal area (46% of the floating tongue area) will enhance the ice discharge by 8.3% due to loss in buttressing.Humbert, A., Helm, V., Neckel, N., Zeising, O., Rückamp, M., Khan, S. A., Loebel, E., Gross, D., Sondershaus, R., and Müller, R.: Precursor of disintegration of Greenland's largest floating ice tongue, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2022-171, in review, 2022

Die Etablierung der unterschiedlichen Register im Bereich der arthroskopischen Chirurgie basiert auf den Erfahrungen, welche mit den ersten Registern gesammelt wurden. Im Unterschied zum Endoprothesenregister Deutschland (EPRD) haben die spater eingefuhrten Register PROMs („patient reported outcome measurments“) integriert, welche webbasiert in unterschiedlichen Zeitabschnitten abgefragt werden. Wie erfolgreich und wertvoll die Registerdaten sind, konnte das KnorpelRegister bereits mit 20 Publikation unter Beweis stellen. Das nachfolgend eingefuhrte Deutschsprachige Arthroskopieregister (DART) und Deutschsprachige Knie Osteotomie Register (DEKOR) fuhren die Entwicklung des KnorpelRegisters fort. Um Registerdaten qualitativ auswerten zu konnen, ist eine grose Anzahl von Patienten erforderlich. Die Register sind daher fur „jedermann“ gedacht und munden in Aussagen und Empfehlungen fur „jedermann“.

The business continuity of radiotherapy practice is of utmost importance for a safe, effective and efficient fight against cancer. Patients rely on uninterrupted therapies even under adverse conditions. The COVID-19 pandemic has caught many radio- therapy institutions unprepared. Centers worldwide had to find ways to master the extraordinary challenges instantly. However, the lack of knowledge, specific guidelines and mitigation strategies exposed radiotherapy centres to unpredictable risks. Intelligent information systems can support the management of severe incidents. The aim of our research was to develop a decision support system that shall help to maintain safe, sustainable and efficient radiotherapy services in pandemic situa- tions. In this work, we present a text-based conversational agent that informs about mitigation measures for radiotherapy practice during a pandemic crisis. The business continuity of radiotherapy practice is of utmost importance for a safe, effective and efficient fight against cancer. Patients rely on uninterrupted therapies even under adverse conditions. The COVID-19 pandemic has caught many radio- therapy institutions unprepared. Centers worldwide had to find ways to master the extraordinary challenges instantly. However, the lack of knowledge, specific guidelines and mitigation strategies exposed radiotherapy centres to unpredictable risks. Intelligent information systems can support the management of severe incidents. The aim of our research was to develop a decision support system that shall help to maintain safe, sustainable and efficient radiotherapy services in pandemic situa- tions. In this work, we present a text-based conversational agent that informs about mitigation measures for radiotherapy practice during a pandemic crisis.

Purpose Aim of this systematic review was to analyze long-term results after meniscus refixation. Methods A systematic literature search was carried out in various databases on studies on long-term results after meniscus refixation with a minimum follow-up of 7 years. Primary outcome criterion was the failure rate. Secondary outcome criteria were radiological signs of osteoarthritis (OA) and clinical scores. Results A total of 12 retrospective case series (level 4 evidence) were identified that reported about failure rates of more than 7 years follow-up. There was no statistical difference in the failure rates between open repair, arthroscopic inside-out with posterior incisions and arthroscopic all-inside repair with flexible non-resorbable implants. In long-term studies that examined meniscal repair in children and adolescents, failure rates were significantly higher than in studies that examined adults. Six studies have shown minor radiological degenerative changes that differ little from the opposite side. The reported clinical scores at follow-up were good to very good. Conclusion This systematic review demonstrates that good long-term outcomes can be obtained in patients after isolated meniscal repair and in combination with ACL reconstruction. With regard to the chondroprotective effect of meniscus repair, the long-term failure rate is acceptable. Level of evidence IV.

YIN YANG 1 (YY1) encodes a dual-function transcription factor, evolutionary conserved between the animal and plant kingdom. In Arabidopsis thaliana, AtYY1 is a negative regulator of ABA responses and floral transition. Here, we report the cloning and functional characterization of the two AtYY1 paralogs, YIN and YANG (also named PtYY1a and PtYY1b) from Populus (Populus trichocarpa). Although the duplication of YY1 occurred early during the evolution of the Salicaceae, YIN and YANG are highly conserved in the willow tree family. In the majority of Populus tissues, YIN was more strongly expressed than YANG. Subcellular analysis showed that YIN-GFP and YANG-GFP are mainly localized in the nuclei of Arabidopsis. Stable and constitutive expression of YIN and YANG resulted in curled leaves and accelerated floral transition of Arabidopsis plants, which was accompanied by high expression of the floral identity genes AGAMOUS (AG) and SEPELLATA3 (SEP3) known to promote leaf curling and early flowering. Furthermore, the expression of YIN and YANG had similar effects as AtYY1 overexpression to seed germination and root growth in Arabidopsis. Our results suggest that YIN and YANG are functional orthologues of the dual-function transcription factor AtYY1 with similar roles in plant development conserved between Arabidopsis and Populus.

The martensite structure of steel is of great importance in mechanical engineering and is usually adjusted by heat treatment. Of particular interest is the morphology of martensite, as it has a significant influence on mechanical properties. In this work, a phase field model is presented, where the order parameter is used to describe the evolution of martensite in order to predict the resulting morphology. In a first step, simulations with two martensite variants with different transformation strains by means of the finite element method in the small strain context show the basic applicability of the model in a two-dimensional environment. With a concept based on the phenomenological theory of martensite crystallography, good agreement with the transformation mechanics of the experiment is achieved. Furthermore, an illustrative three-dimensional simulation takes the crystallographic variants of the Nishiyama–Wasserman orientation relationship into account. The size of the simulation domain corresponds to the size of a prior austenite grain. The calculated block sizes agree with the experimental observations.

Die Verbreitung von Informationen und Meinungsäußerungen unter Einschluss medialer Inhalte erfolgt heutzutage in großem Umfang digital über das öffentlich zugängliche Internet. Angesichts der unüberschaubaren Zahl an online abrufbaren Informationen vermag jeder Internetnutzer allerdings nur einen Bruchteil des tatsächlich verfügbaren Angebots zu konsumieren. Daher ist eine Selektion aus dieser Informations- und Inhaltsfülle erforderlich. Diese Aufgabe übernehmen sog. Medienintermediäre, denen hierdurch für die Aufmerksamkeitssteuerung der Internetnutzer eine zentrale Rolle zuwächst. Um die Aufgaben dieser Zugangssteuerung erfüllen zu können, bedienen sich die Anbieter von Medienintermediären sog. Algorithmen, mit denen sie den Zugang und Verbleib von Informationen sowie die Aggregation, Selektion und Präsentation solcher Informationen steuern. Diese Algorithmen werden deshalb zunehmend auch zum Gegenstand des Rechts, so zuletzt in Gestalt der 2020 in Kraft getretenen Medienintermediärsregulierung des Medienstaatsvertrags (MStV). Vor diesem Hintergrund widmet sich der Beitrag dem in § 93 MStV implementierten Gebot zur Herstellung von Algorithmen-Transparenz durch Medienintermediäre. Hierzu analysiert er, welches Ziel diese Transparenzbestimmung verfolgt. Sodann wird der Transparenzbegriff als Gegenstand des Rechts beleuchtet, bevor näher auf den Inhalt der Transparenzvorgaben nach dem Medienstaatsvertrag eingegangen und die Umsetzung dieser Vorgaben mittels ausgewählter Praxisbeispiele erörtert wird. Ergänzt wird diese Darstellung durch Ausführungen zu den verfassungsrechtlichen Grenzen von Transparenz sowie zu Fragen des Rechtsschutzes. Dem folgt eine Untersuchung von aktuellen unionsrechtlichen Ansätzen und Überlegungen zur Herstellung intermediärsbezogener Transparenz sowie ihres Einflusses auf die nationale Gesetzgebung. Unter anderem kommt der Beitrag zu dem Ergebnis, dass die Transparenzvorgaben des Medienstaatsvertrags verfassungs- und unionsrechtskonform sind. Gerade das Unionsrecht zeigt, dass die Norm einem bereits begonnenen und sich verstärkenden Trend auf EU-Ebene folgt, Transparenz hinsichtlich der Funktionsweise von Algorithmen in unterschiedlichen digitalen Lebensbereichen und mit unterschiedlichen Zwecksetzungen einzufordern und herzustellen. Mit § 93 MStV hat sich der Gesetzgeber im Übrigen für ein Transparenzkonzept entschieden, das an bekannte Vorgaben des Internet- und Datenschutzrechts anknüpft und deshalb in der Praxis ohne substanzielle Schwierigkeiten umsetzbar sein sollte. Dessen ungeachtet handelt es sich bei § 93 MStV um gesetzgeberisches Neuland. Ob dieses Neuland den vom Gesetzgeber erhofften vielfaltssichernden Ertrag hervorzubringen vermag, müssen die nächsten Jahre erweisen.

Flexibility and versatility in production put high demands on the planning, simulation and ramp-up of assembly systems and processes. For this purpose, a digital twin of a laser-based assembly assistance system for manual mounting tasks was developed, implemented and analyzed. A capability model was elaborated using quantitative and qualitative studies. The capability model was realized as a Unity 3D model. In the augmented reality implementation using the Microsoft HoloLens users can control the digital twin through hand gestures and voice control. The implementation shows that the digital twin of the laser-based assembly assistance supports the planning, simulation and training of employees at the shop floor.

ZusammenfassungDer vorliegende Patientenfall thematisiert eine kieferorthopädische Behandlung zur Einstellung von Oberkiefereckzähnen mit der Tendenz zur Verlagerung und Transposition durch mesiale Migration.

Within this work, we utilize the framework of phase field modeling for fracture in order to handle a very crucial issue in terms of designing technical structures, namely the phenomenon of fatigue crack growth. So far, phase field fracture models were applied to a number of problems in the field of fracture mechanics and were proven to yield reliable results even for complex crack problems. For crack growth due to cyclic fatigue, our basic approach considers an additional energy contribution entering the regularized energy density function accounting for crack driving forces associated with fatigue damage. With other words, the crack surface energy is not solely in competition with the time-dependent elastic strain energy but also with a contribution consisting of accumulated energies, which enables crack extension even for small maximum loads. The load time function applied to a certain structure has an essential effect on its fatigue life. Besides the pure magnitude of a certain load cycle, it is highly decisive at which point of the fatigue life a certain load cycle is applied. Furthermore, the level of the mean load has a significant effect. We show that the model developed within this study is able to predict realistic fatigue crack growth behavior in terms of accurate growth rates and also to account for mean stress effects and different stress ratios. These are important properties that must be treated accurately in order to yield an accurate model for arbitrary load sequences, where various amplitude loading occurs., Deutsche Forschungsgemeinschaft, Projekt DEAL

Manganese (Mn) contained in cellulose is partially responsible for an increased consumption of paper bleaching chemicals (like O2, H2O2), consequently diminishing the efficiency in pulp processing, darkening the pulp and deteriorating pulp quality. Usually, Mn in the paper industry is removed employing the environmentally critical EDTA. A greener alternative constitutes, however, the use of siderophores, high-affinity metal-chelating organic compounds that are produced by microorganisms to acquire metals (Fe and Mn among others), like desferrioxamine B (DFOB) or desferrioxamine E (DFOE). The use of native Mn-transporter proteins, like PratA, constitutes another possibility for Mn removal. The evaluation of utilizing siderophores or PratA for Mn removal from cellulose in a circular economy scheme is therefore essential. Firstly, Mn removal from cellulose was performed by immobilizing siderophores or PratA on magnetic beads (M-PVA C22). Secondly, the beads were incubated overnight with a 2% cellulose suspension, allowing Mn-ligand complex formation. Finally, cellulose suspensions were submitted for Mn quantification, employing either the TCPP [Tetrakis(4-carboxyphenyl)porphyrin] method, the PAN [1-(2-pyridylazo)-2-naphthol] method or the Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). When non-immobilized ligands were employed, a 31% Mn removal was achieved; when using immobilized ligands, around 10% Mn removal was obtained. Treated and untreated cellulose was analyzed by SEM and the Mn distribution between the solid and liquid phase was parameterized using adsorption isotherm models. This novel greener method proved to be feasible and easy, leading to potential improvements in the paper industry. Next research steps are to optimize Mn removal and quantify Mn recovery after ligand decoupling before scaling-up.

Phase field modeling of fracture has been in the focus of research for over a decade now. The field has gained attention properly due to its benefiting features for the numerical simulations even for complex crack problems. The framework was so far applied to quasi static and dynamic fracture for brittle as well as for ductile materials with isotropic and also with anisotropic fracture resistance. However, fracture due to cyclic mechanical fatigue, which is a very important phenomenon regarding a safe, durable and also economical design of structures, is considered only recently in terms of phase field modeling. While in first phase field models the material’s fracture toughness becomes degraded to simulate fatigue crack growth, we present an alternative method within this work, where the driving force for the fatigue mechanism increases due to cyclic loading. This new contribution is governed by the evolution of fatigue damage, which can be approximated by a linear law, namely the Miner’s rule, for damage accumulation. The proposed model is able to predict nucleation as well as growth of a fatigue crack. Furthermore, by an assessment of crack growth rates obtained from several numerical simulations by a conventional approach for the description of fatigue crack growth, it is shown that the presented model is able to predict realistic behavior., Deutsche Forschungsgemeinschaft, Projekt DEAL

Background The benefits of the various therapeutic options for the treatment of subacromial impingement syndrome are a topic of ongoing debate. Several studies on the subject are insufficiently evidence-based, with many other studies being considered controversial by members of the field. Nevertheless, a general opinion against surgical interventions is developing in the media in reference to these systematic reviews and meta-analyses based on insufficiently differentiated literature. Aim of the study This article provides an overview of the literature and examines the outcome after arthroscopic subacromial decompression compared with conservative therapy or diagnostic arthroscopy and bursectomy. Conclusion The outcome for patients treated with conservative therapy or subacromial decompression who explicitly suffered from mechanical outlet impingement (MOI) or mechanical non-outlet impingement (MNOI) has not yet been studied. The main problem concerning almost all published studies is that they are based on a mixture of pathologies. It seems likely that especially patients with a mechanical, and therefore structural, narrowing of the subacromial space can profit more from surgical management than patients with unspecific subacromial pain. Differentiation between the pathologies is crucial for the correct treatment decision, not only for the reduction of symptoms, but most importantly for the preservation of the supraspinatus tendon.