297 research outputs found
A Comparative Study of Biot’s Theory and the Linear Theory of Porous Media for Wave Propagation Problems
Poster: MIX-ENABLE Nachhaltige gemischte Bio-Tierhaltung
Posterpräsentation des Projekts und der geplanten Teilprojekte für eine Dissertation
PaNTERA: Proton Radiography towards medical applications
Heavy ion radiotherapy is an accepted form of cancer therapy especially suitable for the precise and effective treatment of tumors close to organs at risk. The high precision of the treatment is currently achieved by using patient geometry data captured using X-ray computed tomography. With the application of new imaging methods directly measuring the density and stopping power of the patient tissue the present accuracy could be further improved.
One of the promising alternatives to X-ray computed tomography is high energy proton radiography capable of providing a precise density analysis of target materials. Within the scope of this work several experimental approaches towards the effective accuracy of this technique regarding density reconstruction were made using different types of targets (simple step wedges and head phantoms). The investigations especially focused on the applicability of radiographic images for treatment planning based on either conventional X-ray data being recalibrated with the help of single proton projections or native proton computed tomography. All of the presented experiments were conducted during parasitic beam times at the LANL pRAD facility in New Mexico, USA. Several issues regarding the stability of the accelerator as well as the optical quality of the available detector systems were disclosed. Nevertheless, high energy proton radiography proved to deliver a more accurate density reconstruction than conventional calibration approaches.
Further investigations with the GSI in-house treatment planning software TRiP98 revealed a significant difference in dose coverage of a virtual tumor volume when using different patient base data (X-ray computed tomography vs. recalibrated X-ray computed tomography vs. proton tomography). Although the current clinical method provided a good result in soft tissue regions, at higher densities, e.g. in the density range of bones, a significantly larger deviation was monitored. This could in specific cases lead to an ineffective treatment of tumors or even to an unwanted dose deposition in healthy organs with the conventional imaging approach.
High energy proton radiography promises to be a suitable technique for medical imaging purposes. Although current facilities are not yet designed for such applications, future treatment centers could be designed in a way to exploit the benefits of this technique. Beforehand, several improvements and modifications to those setups will be mandatory to advance the technique towards clinical implementations. Future experiments for medical applications are scheduled for the FAIR phase 0. Those will focus on including a suitable method for measuring the stopping power of the incident particles. A quality comparison to X-rays at equal dose deposition is planned as well
Characterisation and optimisation of a failure model for high strength aluminium alloys using Nakajima experiments
Convolution quadrature for the wave equation with impedance boundary conditions
We consider the numerical solution of the wave equation with impedance boundary conditions and start from a boundary integral formulation for its discretization. We develop the generalized convolution quadrature (gCQ) to solve the arising acoustic retarded potential integral equation for this impedance problem.
For the special case of scattering from a spherical object, we derive representations of analytic solutions which allow to investigate the effect of the impedance coefficient on the acoustic pressure analytically. We have performed systematic numerical experiments to study the convergence rates as well as the sensitivity of the acoustic pressure from the impedance coefficients.
Finally, we apply this method to simulate the acoustic pressure in a building with a fairly complicated geometry and to study the influence of the impedance coefficient also in this situation
Flyer MIX-ENABLE
MIX-ENABLE ist ein von INRA (Frankreich) geleitetes CoreOrganic-Projekt mit 10 Partnern aus 7 EU-Ländern. Das 3-jährige Projekt begann im April 2018.
Projektinformationen: Hintergrund, Fragestellungen, methodische Ansätze und Ziel
High work satisfaction despite high workload among European organic mixed livestock farmers: a mixed-method approach
Organic mixed livestock farming offers a range of potential benefits for the environment. Due to the diversification of enterprises, this farming system can be associated with a high workload, which means that it could be socially unsustainable. The aim of this study was to understand and explain work satisfaction of farmers running an organic mixed livestock farm. Using a mixed-method approach, quantitative and qualitative data were collected from 102 farmers in seven European countries during face-to-face interviews. We showed for the first time that across Europe and different animal species and category combinations, organic mixed livestock farms can provide a high work satisfaction, despite a high workload. By using a mixed-method approach and a clear framework, we aimed at better understanding work satisfaction. Underlying reasons for work satisfaction included the diversity of tasks, opportunities to learn, autonomy in the work schedule, perceived acknowledgement by consumers, and the contribution to sustainable food production. Factors contributing to work satisfaction identified in the analysis of quantitative data included workload, number of livestock units, mental complexity, proportion of work peaks per year, and the match between wanted free time and time taken off work. The combination of qualitative and quantitative data allowed a deeper understanding of farmers’ work satisfaction and revealed consistent findings. Future research should investigate the relationship between farmers’ work satisfaction and capacity for innovation, flexibility, and adaptation potential
Potential of multi-species livestock farming to improve the sustainability of livestock farms: A review.
Diversified farming systems are proposed as a major mechanism to address the many sustainability issues of today's agriculture. Multi-species livestock farming, i.e. keeping two or more animal species simultaneously on the same farm, is an option that has received little attention to date. Moreover, most studies of multi-species livestock farming are limited, usually focusing on selected dimensions of farm sustainability and addressing lower organizational levels (i.e. within the farm) and rather limited time horizons (e.g. a few weeks in a grazing season). Thus, a comprehensive assessment of multi-species livestock farming in terms of farm sustainability is lacking. In this context, we outline and discuss potential benefits and limitations of multi-species livestock farming for livestock farm sustainability from existing literature and list issues on multi-species livestock farming requiring further research. We show that multi-species livestock farming has the potential to improve the three dimensions of sustainability reviewed - economic viability for farmers, environmental soundness and social acceptability by being respectful of animals and humans - as long as locally relevant farming practices are implemented, especially an appropriate stocking rate during grazing. If relevant practices are not observed, multi-species livestock farming may produce undesirable effects, such as competition for resource acquisition during grazing, parasitic cross-infection and more intense work peaks. Therefore, we identify four focal research areas for multi-species livestock farming. First, characterizing the management of multi-species livestock farms. To do this, we suggest considering the integration of production enterprises (e.g. cattle and sheep enterprises)
within the farm from three perspectives: farming practices (e.g. grazing management), work organization and sales. Second, exploring the complementarity of livestock species on multi-species livestock farms. This is especially true for species combinations that have been largely ignored (e.g. ruminants and monogastrics), even though they may have potential due to complementary diet compositions and resource-acquisition strategies. Third, assessing the sustainability of multi-species livestock farm scenarios (current or alternative) according to the management practices and production conditions, which requires adapting existing methods/models or developing new ones. Fourth, characterizing conditions for success and obstacles for multi-species livestock farming along the value chain from production to consumption, considering stakeholders' objectives, work habits and constraints. Increasing understanding should help prioritize actions and organize them to scale up multi-species livestock farming
B-Cell Reconstitution After Autologous Hematopoietic Stem Cell Transplantation in Multiple Sclerosis
Background and objectives: Autologous hematopoietic stem cell transplantation (aHSCT) is increasingly used to treat aggressive forms of multiple sclerosis (MS). This procedure is believed to result in an immune reset and restoration of a self-tolerant immune system. Immune reconstitution has been extensively studied for T cells, but only to a limited extent for B cells. As increasing evidence suggests an important role of B cells in MS pathogenesis, we sought here to better understand reconstitution and the extent of renewal of the B-cell system after aHSCT in MS.
Methods: Using longitudinal multidimensional flow cytometry and immunoglobulin heavy chain (IgH) repertoire sequencing following aHSCT with BCNU + Etoposide + Ara-C + Melphalan anti-thymocyte globulin, we analyzed the B-cell compartment in a cohort of 20 patients with MS in defined intervals before and up to 1 year after aHSCT and compared these findings with data from healthy controls.
Results: Total B-cell numbers recovered within 3 months and increased above normal levels 1 year after transplantation, successively shifting from a predominantly transitional to a naive immune phenotype. Memory subpopulations recovered slowly and remained below normal levels with reduced repertoire diversity 1 year after transplantation. Isotype subclass analysis revealed a proportional shift toward IgG1-expressing cells and a reduction in IgG2 cells. Mutation analysis of IgH sequences showed that highly mutated memory B cells and plasma cells may transiently survive conditioning while the analysis of sequence cluster overlap, variable (IGHV) and joining (IGHJ) gene usage and repertoire diversity suggested a renewal of the late posttransplant repertoire. In patients with early cytomegalovirus reactivation, reconstitution of naive and memory B cells was delayed.
Discussion: Our detailed characterization of B-cell reconstitution after aHSCT in MS indicates a reduced reactivation potential of memory B cells up to 1 year after transplantation, which may leave patients susceptible to infection, but may also be an important aspect of its mechanism of action
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