Dynamic Beam-Layout Design for MEO High Throughput Satellite Systems

Scientific Conference (2022, December 04)

We propose a traffic-oriented beam-layout optimization framework for a medium Earth orbit (MEO) high throughput satellite (HTS) system. The designed beam-layout plans have the objective of dynamic traffic ... [more ▼]

We propose a traffic-oriented beam-layout optimization framework for a medium Earth orbit (MEO) high throughput satellite (HTS) system. The designed beam-layout plans have the objective of dynamic traffic load balancing with minimal radio resource management. We model and evaluate the high directivity and the high reconfigurability capabilities of next-generation HTS systems that are equipped with a processing power on board. The resulting payload flexibility is compared numerically against the on-ground counterpart. Adequate key performance indicators, such as the Jain’s fairness index, the load distribution gap and optimization convergence time, are used to benchmark the system against state-of-the-art solutions. Results show that a dynamic HTS in MEO is capable of efficiently attaining high quality load balancing performance under realistic spatiotemporally varying traffic demands. [less ▲]

Dynamic career attitudes among master students: Social disparities in employment capabilities.

in Pracana, Clara (Ed.) Social Psychology (2015)

The preparation of students’ future career trajectories is a dynamic process in relation with social and educational determinants, but their interactions must be further investigated. Our objective is to ... [more ▼]

The preparation of students’ future career trajectories is a dynamic process in relation with social and educational determinants, but their interactions must be further investigated. Our objective is to analyze the associations between generic employment capabilities, career attitudes and other related factors among postgraduate students. Method: All master's students recorded in the Centre for Documentation and Information on Higher Education from Luxembourg database were contacted by letter to participate in an online questionnaire. The online questionnaire (French and English) with five scales was scored: 1) Dynamic Career Attitudes (DCA- 13 items); 2) Employability Soft-Skills (ESS-14); 3) Search for Work Self-Efficacy (SWSES - 12 items); 4) Quality of Life domain Autonomy (QLA- 4 items); and 5) Socio-demographical characteristics. The data were analyzed using bivariate tests, correlations and multiple linear regression models. Results: Of the 481 volunteers (26.4 years; SD=5.5) a majority were women, Luxembourgish, unemployed, and had less than or equal to six months of job experiences. Higher the ESS, SWSES and QLA scores, higher was the DCA score. Nationality, being unemployed, having less than six months of job experiences and being in the first year of master were associated with lower Dynamic Career Attitudes score. Conclusion: Covering the whole period of the master’s degree, internship activities and proactive workshops may be developed to improve generic employment capabilities and quality of autonomy. The Dynamic Career Attitudes scale appears an appropriate instrument to evaluate the efficacy of the university career services programme. [less ▲]

Dynamic change of host gastrointestinal microbiome and immune status in relation to mucosal barrier effects during chemotherapy and immune ablative intervention in humans

Poster (2014, April)

The human gastrointestinal tract is colonized by communities of endogenous microbes, commonly referred to as the microbiome. Here, the microbiota are in close contact with the host intestinal mucosa and ... [more ▼]

The human gastrointestinal tract is colonized by communities of endogenous microbes, commonly referred to as the microbiome. Here, the microbiota are in close contact with the host intestinal mucosa and its innate and adaptive immune systems. The fact that certain stimuli induce an inflammatory response whereas others induce tolerance suggests, that the host immune system interacts with the microbiota and vice versa in different ways. However, the exact details of theses interactions remain largely unknown. It is known that cancer treatment can result in severe adverse effects like mucositis and in combination with allogeneic stem cell transplantation (Tx), in graft-versus host disease (GvHD). However, there is at present only sparse information available on the effects of chemotherapy on the intestinal microbiota and resulting changes in microbiome-immune system interactions. Almost no data exists on the effect of allogeneic stem cell Tx on the composition of the gastrointestinal microbiota. In this project, we are studying the complex interactions between the host and the intestinal microbiota after chemotherapy with or without allogeneic Tx and the occurrence of severe adverse side effects such as mucositis and GvHD. Using a systems biology approach including metagenomics and RNAseq, fecal samples and blood plasma samples from patients undergoing these treatments for malignancies will be analysed to identify the composition of the gastrointestinal microbiome and bacterial small RNAs. The main research hypothesis is that there are quantitative and qualitative changes in the gastrointestinal microbiome following chemotherapy and allogeneic Tx which are linked to the immune status of the patients and possible treatment side-effects, in particular mucositis and GvHD. We aim to provide knowledge on how the host's intestinal mucosa and immune system influence the gastrointestinal microbiome and on the role and involvement of the gastrointestinal microbiota in development in mucositis and GvHD. Importantly, this could help in the formulation of measures to prevent mucositis and GvHD development. [less ▲]

Dynamic change of the human gastrointestinal microbiome in relation to mucosal barrier effects during chemotherapy and immune ablative intervention

Doctoral thesis (2017)

Numerous studies have demonstrated that the gastrointestinal tract (GIT) microbiota plays important roles for the human host. Since the GIT microbiota interfaces with the immune system and represents a ... [more ▼]

Numerous studies have demonstrated that the gastrointestinal tract (GIT) microbiota plays important roles for the human host. Since the GIT microbiota interfaces with the immune system and represents a first line of defense against infectious agents, interest has grown in whether the GIT microbiota may influence the outcome of different anticancer treatments. In this study, the GIT of pediatric patients with different cancer types as well as adult patients with hematologic malignancies undergoing an allogeneic hematopoietic stem cell transplantation were sampled throughout their treatment. In order to deeply profile not only the composition of the community, but also the functional capacity and expression, recently developed wet- and dry-lab methodologies for integrated multi-omic analyses were applied. The trajectories of the prokaryotic and microeukaryotic GIT communities of the patients were described in detail using 16S, 18S rRNA gene amplicon sequencing, as well as metagenomic and metatranscriptomic shotgun sequencing. Indeed, changes in the GIT microbiome in response to treatment were detected. Some changes that are generally thought to be detrimental for human health were detected during treatment, such as a decrease in alpha-diversity, a decrease in relative abundance of bacteria associated with health-promoting properties (such as Blautia spp., Roseburia spp. and Faecalibacterium spp.), as well as an increase in the relative abundance of antibiotic resistance genes. These changes were more pronounced in the adult hematology patients than in the pediatric patients, which is likely due to the more intensive treatment. Some observations need further investigation in order to explain their implication in human health. For example, in the pediatric patients, lower relative abundance of Akkermansia muciniphila was associated with mucositis and functional gene categories that are linked to bacteriophages or the bacterial defense mechanism against bacteriophages were associated with the overall status of the patient and mucositis development. Importantly, in both cohorts, high inter-individual but also high intra-individual variation in the prokaryotic communities were detected while the microeukaryotic community did not exhibit drastic changes. In conclusion, the employed integrated multi-omics analysis allowed detailed profiling of the GIT community including archaea, bacteria, eukaryotes and viruses as well as the functional potential including antibiotic resistance genes. In the future, analysis of the individual-specific processes within the GIT microbial community of patients throughout treatment might allow to adjust therapy regimens accordingly and improve the overall outcome of the therapy. [less ▲]

Dynamic context logic

in Logic, Rationality, and Interaction (2009)

Building on a simple modal logic of context, the paper presents a dynamic logic characterizing operations of contraction and expansion on theories. We investigate the mathematical properties of the logic ... [more ▼]

Building on a simple modal logic of context, the paper presents a dynamic logic characterizing operations of contraction and expansion on theories. We investigate the mathematical properties of the logic, and show how it can capture some aspects of the dynamics of normative systems once they are viewed as logical theories. [less ▲]

Dynamic controllers for column synchronization of rotation matrices: a QR-factorization approach

in Automatica (2018), 93

In the multi-agent systems setting, this paper addresses continuous-time distributed synchronization of columns of rotation matrices. More precisely, k specific columns shall be synchronized and only the ... [more ▼]

In the multi-agent systems setting, this paper addresses continuous-time distributed synchronization of columns of rotation matrices. More precisely, k specific columns shall be synchronized and only the corresponding k columns of the relative rotations between the agents are assumed to be available for the control design. When one specific column is considered, the problem is equivalent to synchronization on the (d-1)-dimensional unit sphere and when all the columns are considered, the problem is equivalent to synchronization on SO(d). We design dynamic control laws for these synchronization problems. The control laws are based on the introduction of auxiliary variables in combination with a QR-factorization approach. The benefit of this QR-factorization approach is that we can decouple the dynamics for the $k$ columns from the remaining d-k ones. Under the control scheme, the closed loop system achieves almost global convergence to synchronization for quasi-strong interaction graph topologies. [less ▲]

Dynamic cumulative activity of transcription factors as a mechanism of quantitative gene regulation.

in Genome Biology (2007), 8(9), 181

BACKGROUND: The regulation of genes in multicellular organisms is generally achieved through the combinatorial activity of different transcription factors. However, the quantitative mechanisms of how a ... [more ▼]

BACKGROUND: The regulation of genes in multicellular organisms is generally achieved through the combinatorial activity of different transcription factors. However, the quantitative mechanisms of how a combination of transcription factors controls the expression of their target genes remain unknown. RESULTS: By using the information on the yeast transcription network and high-resolution time-series data, the combinatorial expression profiles of regulators that best correlate with the expression of their target genes are identified. We demonstrate that a number of factors, particularly time-shifts among the different regulators as well as conversion efficiencies of transcription factor mRNAs into functional binding regulators, play a key role in the quantification of target gene expression. By quantifying and integrating these factors, we have found a highly significant correlation between the combinatorial time-series expression profile of regulators and their target gene expression in 67.1% of the 161 known yeast three-regulator motifs and in 32.9% of 544 two-regulator motifs. For network motifs involved in the cell cycle, these percentages are much higher. Furthermore, the results have been verified with a high consistency in a second independent set of time-series data. Additional support comes from the finding that a high percentage of motifs again show a significant correlation in time-series data from stress-response studies. CONCLUSION: Our data strongly support the concept that dynamic cumulative regulation is a major principle of quantitative transcriptional control. The proposed concept might also apply to other organisms and could be relevant for a wide range of biotechnological applications in which quantitative gene regulation plays a role. [less ▲]

Dynamic Deontic Logic for Permitted Announcements

in 19th International Conference on Principles of Knowledge Representation and Reasoning, KR 2022 (2022)

In this paper, we introduce and study a dynamic deontic logic for permitted announcements. In our logic framework, it is permitted to announce something if announcing it would not lead to forbidden ... [more ▼]

In this paper, we introduce and study a dynamic deontic logic for permitted announcements. In our logic framework, it is permitted to announce something if announcing it would not lead to forbidden knowledge. It is shown that the logic is not compact, and we propose a sound and weakly complete Hilbert-style axiomatisation. We also study the computational complexity of the model checking problem and the decidability of the satisfiability problem. Finally, we introduce a neighbourhood semantics with a strongly complete axiomatisation. [less ▲]

Dynamic Dependence in Corporate Credit

E-print/Working paper (2013)

Dynamic encounters in sociolinguistic enquiry: Meeting participants, reflexivity and anonymity

in Ibarrondo, Ludovic; Erfurt, Jürgen (Eds.) Linguistic heterogeneity: Questions of methodology, analysis tools and contextualization (2023)

This paper discusses and problematizes three conflated ethically related questions, namely the encounters with the participants, reflexivity and anonymity in research. Within the framework of ... [more ▼]

This paper discusses and problematizes three conflated ethically related questions, namely the encounters with the participants, reflexivity and anonymity in research. Within the framework of sociolinguistics and other disciplines, ethnography has been a prominent research methodology used to generate data through participant observation and interviews. Based on data from an ethnographic project concerning the intersections between language and migration into Luxembourg, this paper aims to offer a critique of positivist ideologies which argue that researchers need to keep distance from the object of study in order to be objective in research. This distancing often means anonymizing blindly (i.e. without checking consent) the research participants. However, one must remember that one is researching ‘human subjects’ who, similar to the researchers, have their own agendas, desires and life goals (Juffermans, 2010). The paper empirically demonstrates that there is a need to ‘move away from representing identities of researcher and research participants in fixed and binary terms’ (Martin- Jones et al., 2017, 190) of insider and outsider. It concludes that ‘unless required by sensitive nature of the data collected’ (Juffermans, 2015,15), anonymity needs to be negotiated to the extent that it does not erase the voice and choice of agentive participants. [less ▲]