25 research outputs found
Infinitesimal Time Reparametrisation and Its Applications
No full textA geometric approach to Sundman infinitesimal time-reparametrisation is given and some of its applications are used to illustrate the general theory. Special emphasis is put on geodesic motions and systems described by mechanical type Lagrangians. The Jacobi metric appears as a particular case of a Sundman transformation. © 2022, The Author(s)
Many-Revolution Earth-Centred Solar-Sail Trajectory Optimisation Using Differential Dynamic Programming
No full textThis work demonstrates the usability of differential dynamic programming (DDP) to obtain optimal Earth-centred solar-sail trajectories. The dynamical model is implemented as a two-body problem, augmented with an ideal solar-sail reflectance model and accounts for eclipses. The numerical performance of the optimisation algorithm is enhanced by integrating the sailcraft state in modified equinoctial elements and performing a Sundman transformation to change the independent variable from time to the true anomaly. The DDP algorithm is proven to be robust for trajectories extending up to 500 revolutions and, compared to known locally optimal steering laws, allows to obtain equally optimal solutions. The latter is demonstrated in this paper through a set of test cases that range from theoretical scenarios to realistic mission applications, including increasing the specific orbital energy of NASA’s upcoming ACS3 mission. Additionally, the algorithm's ability to cope with different optimisation settings, perturbing accelerations and constraints is demonstrated.Astrodynamics & Space Mission
The asthma candidate gene <it>NPSR1 </it>mediates isoform specific downstream signalling
No full textAbstract Background Neuropeptide S Receptor 1 (NPSR1, GPRA, GPR154) was first identified as an asthma candidate gene through positional cloning and has since been replicated as an asthma and allergy susceptibility gene in several independent association studies. In humans, NPSR1 encodes two G protein-coupled receptor variants, NPSR1-A and NPSR1-B, with unique intracellular C-termini. Both isoforms show distinct expression pattern in asthmatic airways. Although NPSR1-A has been extensively studied, functional differences and properties of NPSR1-B have not yet been clearly examined. Our objective was to investigate downstream signalling properties of NPSR1-B and functional differences between NPSR1-A and NPSR1-B. Methods HEK-293 cells transiently overexpressing NPSR1-A or NPSR1-B were stimulated with the ligand neuropeptide S (NPS) and downstream signalling effects were monitored by genome-scale affymetrix expression-arrays. The results were verified by NPS concentration-response and time series analysis using qRT-PCR, cAMP and Ca2+ assays, and cAMP/PKA, MAPK/JNK and MAPK/ERK pathway specific reporter assays. Results NPSR1-B signalled through the same pathways and regulated the same genes as NPSR1-A, but NPSR1-B yielded lower induction on effector genes than NPSR1-A, with one notable exception, CD69, a marker of regulatory T cells. Conclusions We conclude that NPSR1-B is regulating essentially identical set of genes as NPSR1-A, with few, but possibly important exceptions, and that NPSR1-A induces stronger signalling effects than NPSR1-B. Our findings suggest an isoform-specific link to pathogenetic processes in asthma and allergy.</p
The welfare of ill and injured feedlot cattle: a review of the literature and implications for managing feedlot hospital and chronic pens
No full textBy definition, ill and injured animals are on the negative valence of animal welfare. For beef cattle kept in feedlot settings, advances in cattle health management have resulted in a greater understanding and prevention of illness and injury. However, the management of cattle once they become ill and injured is an understudied area, and there are gaps in knowledge that could inform evidence-based decision-making and strengthen welfare for this population. The aim of this review is to provide a comprehensive overview of the acquired knowledge regarding ill and injured feedlot cattle welfare, focusing on existing knowledge gaps and implications for hospital and chronic pen management and welfare assurance. Ill and injured feedlot cattle consist of acutely impaired animals with short-term health conditions that resolve with treatment and chronically impaired animals with long-term health conditions that may be difficult to treat. A literature search identified 110 articles that mentioned welfare and ill and injured feedlot cattle, but the population of interest in most of these articles was healthy cattle, not ill and injured cattle. Articles about managing ill and injured cattle in specialized hospital (n = 12) or chronic (n = 2) pens were even more sparse. Results from this literature search will be used to outline the understanding of acutely and chronically ill and injured feedlot cattle, including common dispositions and welfare considerations, behavior during convalescence, and strategies for identifying and managing ill and injured cattle. Finally, by working through specific ailments common in commercial feedlot environments, we illustrate how the Five Domains Model can be used to explore feelings and experiences and subsequent welfare state of individual ill or injured feedlot cattle. Using this approach and our knowledge of current industry practices, we identify relevant animal-based outcomes and critical research questions to strengthen knowledge in this area. A better understanding of this overlooked topic will inform future research and the development of evidence-based guidelines to help producers care for this vulnerable population.This article is published as Sundman ER, Dewell GA, Dewell RD, Johnson AK, Thomson DU and Millman ST (2024) The welfare of ill and injured feedlot cattle: a review of the literature and implications for managing feedlot hospital and chronic pens. Front. Vet. Sci. 11:1398116. doi: 10.3389/fvets.2024.1398116. © 2024 Sundman, Dewell, Dewell, Johnson, Thomson and Millman. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms
International customer returns : Case: Varusteleka Oy
No full textThis thesis studies the possibilities of outsourcing reverse logistics for a commissioning company. The thesis is divided into four parts; the introduction and theory, current situation, the possible solutions, and discussion.
In the introduction, the case and case company are introduced.
The study aims to evaluate outsourcing reverse logistics and answers the research question: What is the most efficient way to handle customer returns from North America.
The second part consists of theory. The key concepts are introduced there, as well as the way in which the theory and concepts are applied to this study.
The third part concerns possible third-party logistics providers. Their service portfolio is presented and evaluated with an eye on suitability to the commissioning company.
In the fourth part, conclusions are drawn and discussed by the author. From the evaluated 3PL companies none stood out to be the clearly the best option for the commissioning company. However, all of the three should be taken into consideration when deciding how to handle the North American customer returns
An overview of research on gender in Spanish society
No full textThis article presents an overview of research on gender in Spanish society. Six areas of literature are examined including families, education, work, politics, sexuality, and men. The author argues that political factors have shaped the development of sociology of gender in Spain and that there are still important gaps in coverage in this area of sociological inquiry.Publicad
Calphad Modeling of LRO and SRO Using ab initio Data
No full textResults from DFT calculations are in many cases equivalent to experimental data. They describe a set of properties of a phase at a well-defined composition and temperature, T, most often at 0 K. In order to be practically useful in materials design, such data must be fitted to a thermodynamic model for the phase to allow interpolations and extrapolations. The intention of this paper is to give a summary of the state of the art by using the Calphad technique to model thermodynamic properties and calculate phase diagrams, including some models that should be avoided. Calphad models can decribe long range ordering (LRO) using sublattices and there are model parameters that can approximate short range ordering (SRO) within the experimental uncertainty. In addition to the DFT data, there is a need for experimental data, in particular, for the phase diagram, to determine the model parameters. Very small differences in Gibbs energy of the phases, far smaller than the uncertainties in the DFT calculations, determine the set of stable phases at varying composition and T. Thus, adjustment of the DFT results is often needed in order to obtain the correct set of stable phases.(OLD) MSE-
Many-revolution Earth-centred solar-sail trajectory optimisation using differential dynamic programming
No full textThis thesis demonstrates the usability of differential dynamic programming (DDP) to obtain, for the first time, globally optimal Earth-centred solar-sail trajectories. To this end, DDP is combined with a global optimisation heuristic, monotonic basin hopping. The dynamical model is implemented as a two-body problem, augmented with an ideal solar-sail reflectance model and accounts for eclipses. The numerical performance of the optimisation algorithm is enhanced by integrating the sailcraft state in modified equinoctial elements and performing a Sundman transformation to change the independent variable from time to the true anomaly. The DDP algorithm is proven to be robust for trajectories extending up to 500 revolutions and, compared to known locally optimal steering laws, allows to obtain more or equally optimal solutions. The latter is demonstrated in this paper through a set of test cases that range from theoretical scenarios to realistic mission applications, including increasing the specific orbital energy of NASA’s upcoming ACS3 mission. Additionally, the algorithm's ability to cope with different optimisation settings, perturbing accelerations and constraints is demonstrated.Aerospace Engineerin
Differential dynamic programming applied to interplanetary solar-sail trajectory optimization
No full textRecent studies have shown the feasibility of differential dynamic programming (DDP) in optimizing Earth-centered solar-sail trajectories. In order to further demonstrate the ability of DDP in the optimization of solar-sail trajectories, this work investigates the performance of DDP for optimizing interplanetary solar-sail trajectories. The selected dynamical framework is based on the two-body problem, augmented with an ideal solar-sail force model. A superior numerical performance is obtained for the optimization algorithm by propagating the state in modified equinoctial elements and applying a Sundman transformation to change the independent variable from time to the true anomaly. The developed algorithm finds similar or more optimal solutions than locally optimal steering laws for the maximization of different orbital elements. In addition, constrained time-optimal Earth-Mars orbital transfers are investigated for different sail performance levels. The DDP algorithm is proven to be efficient and robust for different optimization settings and initial guesses for solar-sail trajectory optimization in the interplanetary regime.Aerospace Engineering | Astrodynamics & Space Mission
Emancipation and Christian Feminism [Elektronisk resurs] : A Critical Study in Ethics of Subjectivity, Vulnerability, and Relationality
No full textThis study explores the emancipatory potential in different strands of contemporary Christian feminist theology. The study develops a comprehensive understanding of how subjectivity, vulnerability, and relationality intersect with and impact Christian feminist ethics, which seeks to counteract patriarchy and promote emancipation. This is operationalized by the research question: How do different understandings of subjectivity, vulnerability, and relationality relate to Christian feminist ethics and its emancipatory potential? To answer this, the author explores how subjectivity, vulnerability, and relationality are understood in three prominent models of contemporary Christian feminist ethics as devised by Susan Frank Parsons, Catharine Keller, and Denise M. Ackermann.The theoretical framework used to analyze the views of the three theologians draws primarily on the works of Judith Butler and Hille Haker. Additionally, Michel Foucault’s understanding of power is crucial to assessing different models’ emancipatory potential. The study challenges prevalent perspectives that are often found in Christianity, and seeks to move beyond such ideologies and practices that use Christian traditions to legitimize domination, especially of women.The author argues that a dialectical understanding of subjectivity, vulnerability, and relationality provides new critical resources for Christian feminist ethics. Ethics and theology are seen as mutually reinforcing; and it is argued that Christian feminism should embrace a self-reflexive stance that is devoid of triumphalism, and support a theology that does not promote or support domination of others.The author argues for a constructivist approach to gender, since it provides more nuanced resources for the critique of different forms of patriarchy if compared with essentialism, which risks reinforcing dualisms that could support hierarchical divisions. As a critique of the mind/body dualism devised after Descartes, the author argues for a dialectical approach to mind and body—an approach that challenges hierarchies and domination. Subjectivity is argued to be constituted relationally; and vulnerability, as an ontological condition of human existence, should be embraced rather than eliminated.</p
