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Family structures and entrepreneurial practices – the role of monogamy and polygamy in Tanzania
No full textThis study explores how social inequality, particularly within family structures in Tanzania, influences entrepreneurial practices. In the context of these Grand Challenges, entrepreneurship requires a comprehensive understanding of social and cultural contexts. Based on the Entrepreneurship-as-Practice (EaP) theory, we studied how monogamous and polygamous family structures influence entrepreneurial practices through access to resources and social order and power. Our empirical study of 22 focus group discussions among 179 rural coffee entrepreneurs in rural Tanzania preliminary identified two social mechanisms: resource allocation and social order and power. We contribute to EaP by identifying context-specific entrepreneurial practices related to power, resource allocation, and role negotiation within monogamous and polygamous family structures, thereby illustrating the role of family structures as critical sites of practice. Moreover, we will contribute to the gender and power stream of entrepreneurship by demonstrating how families as social institutions shape gender-specific power relations and normative orders
The nature of lignin and implications for its technical use as a source for biogenic aromatics — a review
No full textThe composite material lignocellulose makes up the majority of biomass on earth and is characterized by a high biological and chemical resistance, which is essentially caused by the phenylpropanoid polymer lignin. Thus, the removal and depolymerization of lignin to produce aromatic chemicals can significantly enhance the material usability of all lignocellulose constituents. This review summarizes the current state of knowledge on the nature of lignin, including its biosynthesis, structure, chemistry and biodegradation. Second, it attempts to derive implications regarding the technical valorization of lignin from native biomass through depolymerization. Finally, the consequences of the findings for conventional, recently developed and future processes valorizing lignocellulose are assessed, and the associated technical and economic hurdles are discussed. It becomes clear that lignin depolymerizability is restricted in established pulping processes, primarily due to repolymerization reactions. Strategies avoiding lignin repolymerization involve an increased process complexity and additional economic expenditure but might enable an increased value creation from lignocellulosic biomass
Hip joint loading during sports activities after hip replacement: is there still room for more? Subjective and objective aspects
No full textHip joint replacement with total hip arthroplasty is a frequently performed and highly successful treatment option that is increasingly being offered to younger patients. Due to their longer life expectancy, the longevity expectations for the endoprosthesis have also increased. Physical activity and sports have a positive effect on the risk of loosening. There is no scientific evidence that participation in any specific sport adversely affects the longevity of a hip endoprosthesis. Nevertheless, recommendations to patients vary widely from surgeon to surgeon, and some types of sport are still generally discouraged. This article provides an overview of both recent and older studies addressing the question "What sports are still permissible with an artificial hip?" It attempts to clarify that high joint forces are not necessarily associated with high risk of damage, as the anatomy of muscles and bones, together with muscle function, is optimised to accomodate higher loads. High forces pose a risk only if they are applied in directions not physiologically intended or if the implant is poorly anchored in the bone. The principle that only sports which can be performed with sufficient coordination should be undertaken is therefore certainly correct. Overall, patients should be encouraged to engage in activities in which they feel comfortable and are aware of their own limitations and risks. Hip resurfacing represents an option for a carefully selected patient population, potentially allowing for a return to elite sports. However, the indication requires careful consideration of the local and systemic risks associated with metalon- metal articulations, as well as the patient's age and athletic aspirations. The extent to which new developments without a metal-on-metal articulation may allow for an expanded indication must be carefully evaluated. Clear guidance from the surgeon to the patient regarding the timeline and postoperative activity following hip replacement with an H-TEP or hip resurfacing is necessary to support patient confidence.Der Ersatz des Hüftgelenks mit einer Hüft-Totalendoprothese ist eine häufig durchgeführte, äußerst erfolgreiche Therapieoption, die auch immer jüngeren Patienten angeboten wird. Durch deren höhere Lebenserwartung sind die Standzeiterwartungen der Endoprothese ebenfalls erhöht. Physische Belastungen und sportliche Aktivitäten wirken sich positiv auf das Lockerungsrisiko aus. Es gibt keine wissenschaftliche Evidenz, dass sich das Ausüben einer gewissen Sportart nachteilig auf die Lebensdauer einer Hüftendoprothese auswirkt, trotzdem divergieren die Empfehlungen an die Patienten in Abhängigkeit des Operateurs stark, und von einigen Sportarten wird immer noch generell abgeraten. Der Beitrag gibt eine Übersicht über die neueren (und älteren) Studien zu der Frage „Was ist mit meiner künstlichen Hüfte sportlich noch erlaubt?“ und versucht zu verdeutlichen, dass hohe Gelenkkräfte nicht in Relation zu einer hohen Gefährdung stehen, da die Anatomie von Muskeln und Knochen sowie die Muskelfunktion dahingehend optimiert sind, auch höhere Belastungen des Bewegunsapparates zu ermöglichen. Eine hohe Kraft bedeutet nur dann eine Gefahr, wenn diese nicht in der physiologisch vorgesehenen Richtung auftritt oder wenn das Implantat nicht gut im Knochen verankert ist. Der Grundsatz, dass nur Sportarten ausgeübt werden sollen, die koordinativ beherrscht werden, ist somit sicher richtig. Insgesamt sollten Patienten ermutigt werden, an Aktivitäten teilzunehmen, bei denen sie sich wohlfühlen und sich ihrer eigenen Grenzen und Risiken bewusst sind. Der Oberflächenersatz des Hüftgelenks stellt für ein eng selektiertes Patientenkollektiv eine Option dar, die die Rückkehr zum Spitzensport ermöglichen kann. Die Indikationsstellung erfordert jedoch eine sorgfältige Abwägung der lokalen und systemischen Risiken der Metall-auf-Metall-Gleitpaarungen sowie des Alters und des sportlichen Anspruchs des Patienten. Inwieweit neue Entwicklungen ohne eine Metall-Metall-Gelenkartikulation eine erweiterte Indikation erlauben, muss sorgfältig untersucht werden. Es bedarf klarer Empfehlungen für den Patienten durch den Operateur über die Zeitschiene und das Verhalten nach dem Ersatz des Hüftgelenks durch eine H-TEP oder einen Hüftoberflächenersatz, um das Vertrauen des Patienten in sein Kunstgelenk zu unterstützen. Verbote einzelner Sportarten sind wissenschaftlich nicht begründbar. Der Hinweis, dass gefährliche Sportarten oder die Ausübung von Sportarten, die nicht beherrscht werden, nach H-TEP nicht weniger gefährlich sind, sollte aber unbedingt gegeben werden
Model-based aircraft representations: building blocks to enable digital twins for retrofitting comprehensive and long-living assets
No full textDigital twins, or virtual representations of physical assets, are becoming increasingly popular and useful in a variety of industries. However, the creation of digital twins for comprehensive assets such as aircraft poses significant challenges, especially when performed by third parties in the later stages of the asset’s lifecycle. Information about the current state of the asset is only available in the form of a large number of different documents that record the various changes made throughout its life. Detailed information from the creation of the asset, or a holistic representation of its current state, is rarely to be found. This paper explores these challenges and a possible solution, with a focus on recombining the fragmentary information occurring during the cabin retrofit of aircraft. It presents an approach based on a model-based methodology structured around six distinct building blocks. By leveraging the common characteristics of aircraft, this approach enhances the reusability of information and systematically builds a comprehensive knowledge base. This database contains a set of representations for a family of products with common characteristics, eliminating the need to repeatedly acquire identical information. A proposed access system provides improved access to essential documentation for activities such as the design of new cabin layouts and the planning of aircraft cabin retrofits. The paper concludes by applying the presented approach to a practical case study, demonstrating its applicability through a retrofit scenario of a mock-up cabin section of an Airbus A320.Bundesministerium für Wirtschaft und Energie (BMWE
Family structures, power relations, and entrepreneurial practices – The role of monogamy and polygamy among rural entrepreneurs in Tanzania
No full textLarge social phenomena can be understood as Grand Challenges, such as climate change, digitalization, global health crises and societal inequality, which have far-reaching effects on societies worldwide and are prominent in academic and political debates (Jarzabkowski et al., 2019; Lauche et al., 2024). These large-scale societal issues disrupt existing structures and create new demands for coordinated action across institutional, organizational, and individual levels (George et al., 2016; Ferraro et al., 2015). Grand Challenges are characterized as complex problems that transcend national and sectoral boundaries (Ferraro et al., 2015). Unlike well-defined technical problems, Grand Challenges are dynamic, emergent, and deeply embedded in social systems, often involving conflicting stakeholder interests and power asymmetries (George et al., 2016). Although significant research has been devoted to tackling those challenges, social inequality – defined as the unequal distribution of resources, opportunities, and power across social groups – remains underexplored. More precisely, inequality issues – although widely acknowledged – have largely been treated as a backdrop for other Grand Challenges, rather than as a Grand Challenge in its own right, particularly with regard to its micro-level manifestations in everyday practices
Do We Need Pre-Processing for Deep Learning Based Ultrasound Shear Wave Elastography?
No full textEstimating the elasticity of soft tissue can provide useful information for various diagnostic applications. Ultrasound shear wave elastography offers a non-invasive approach. However, its generalizability and standardization across different systems and processing pipelines remain limited. Considering the influence of image processing on ultrasound based diagnostics, recent literature has discussed the impact of different image processing steps on reliable and reproducible elasticity analysis. In this work, we investigate the need of ultrasound pre-processing steps for deep learning-based ultrasound shear wave elastography. We evaluate the performance of a 3D convolutional neural network in predicting shear wave velocities from spatio-temporal ultrasound images, studying different degrees of pre-processing on the input images, ranging from fully beamformed and filtered ultrasound images to raw radiofrequency data. We compare the predictions from our deep learning approach to a conventional time-of-flight method across four gelatin phantoms with different elasticity levels. Our results demonstrate statistically significant differences in the predicted shear wave velocity among all elasticity groups, regardless of the degree of pre-processing. Although pre-processing slightly improves performance metrics, our results show that the deep learning approach can reliably differentiate between elasticity groups using raw, unprocessed radiofrequency data. These results show that deep learning-based approaches could reduce the need for and the bias of traditional ultrasound pre-processing steps in ultrasound shear wave elastography, enabling faster and more reliable clinical elasticity assessments
Exploring Algorithmic Assemblages Through Multimodal Inquiry
No full textWe explore the increasing role of algorithms in organizational processes, conceptualized as “algorithmic organizing.” As algorithms move from being mere tools to embedded drivers of organizational processes, they redefine traditional boundaries in work practices. Drawing on the assemblage perspective, which treats algorithms as dynamic networks of human and non-human actors, we emphasize the sociomaterial interactions that shape algorithmic organizing. While traditional approaches to studying algorithmic organizing focus on verbal communication, we advocate for a multimodal research design that incorporates multiple modes, including but not limited to verbal/textual, visual, material, emotional, embodied, and spatial. Such an approach uncovers how meaning is constructed through layered interactions within algorithmic assemblages where agency is distributed among technical and human elements. We provide a methodological framework for multimodal research and illustrate its utility for investigating evolving sociomaterial processes in organizational contexts using empirical examples from our ongoing research within an IT consultancy. Our findings contribute to management scholarship by offering insights into how algorithmic organizing can be studied as a continuous, multimodal process, enhancing the transparency and accountability of algorithmic systems in organizations
Aktuelle Entwicklungen und Anwendungen von medizinischen Modellen und Phantomen
No full textDieses Kapitel fokussiert sich auf die Entwicklung von medizinischen Modellen, welche durch das interdisziplinäre Forschungsfeld eine besondere Herausforderung darstellt. Zentrum der Forschung stellen unter anderem Trainingsmodelle für die tierversuchsfreie Ausbildung von medizinischem Personal sowie Phantome für die medizinische Bildgebung dar
Fluted stem designs enhance surgical precision and primary stability in cementless revision hip arthroplasty – a cadaver study
No full textBackground: Cortical contact of the stem is a key determinant for primary stability in cementless revision hip arthroplasty. This matched-pair cadaveric study evaluated whether implant designs that increase cortical contact improve primary fixation of cementless revision stems Methods: Ten paired femora received either a tapered monoblock RECLAIM™ stem with advanced spline (RAS) geometry or an identically sized prototype solid stem. Axial seating and rotation were recorded using dynamic image correlation during implantation. Specimens were cyclically loaded up to 200 % body weight, after which torque-to-failure was measured Findings: Both designs showed mean micromotion <50 μm during cyclic loading, consistently favourable for osseointegration. However, solid stems rotated more during implantation than RAS stems (3.6 ± 5.0° vs. 0.5 ± 0.6°, p = 0.088). The cortical contact area of the solid stems was 43.6 % larger than RAS stems (p < 0.001) without an impact on superior fixation: Axial subsidence and rotation during cyclic loading did not differ significantly between the designs but two solid-stem specimens fractured under high loading. Torque-to-failure of the RAS stems was 38.7 ± 7.5 nm, exceeding that of solid stems by 24.3 % (p = 0.032) Interpretation: These findings suggest that maximising circumferential contact by implant design alone cannot compensate for irregularities of the femoral canal. Whereas solid stems wedge firmly only at the cost of positioning accuracy and increased fracture risk, the thin splines of the RAS design engage the cortex progressively, guide the implant to the planned depth, and augment torsional resistance without excessive press-fit. Tapered stems with cortex-indenting splines improve primary stability in cementless revision hip arthroplasty more effectively than increasing contact area alone
On neural network data predistortion and constellation shaping for satellite channels
No full textIn communication over transparent satellite payloads,
traveling wave-tube amplifier (TWTA) cause nonlinear distortion
to the transmit signal. Together with filters involved in the
transmission chain, the TWTA causes distorted decision regions
(warping) and intersymbol interference (ISI) at the matched
filter output. This nonlinear channel can be compensated by
means of data predistortion. The remaining interference results
can be interpreted as a channel and the transmit constellation
can be optimized for the joint channel with influences from
additive white Gaussian noise (AWGN) and phase noise. This
work shows how constellation shaping and data predistortion
can be designed using neural networks. Particularly, a novel data
predistortion algorithm based on a recurrent neural network
(RNN) which accounts for the ISI is presented. For constellation
shaping, different constrained optimization techniques are
presented, including quadrant-symmetric optimization, spiral
constellations and amplitude and phase-shift keying (APSK)
constellations. All constellations are shaped by implementing the
communication chain as an autoencoder, which is trained on
a channel with the abovementioned impairments, which occur
in satellite links. Resulting constellations are presented together
with data predistortion, bit error rate (BER) and information
rates