The energetic relationship between ports and cities:how the role of shared values is under pressure

Worldwide, ports are subject to the same trends such as globalization, increase in scale of the modus operandi and the process of containerization. These are general dynamics that are responsible for a changing relationship between the port and the city where it is located. This paper aims to describe and explain the developments that three port regions in Europe have experienced over the last decades, i.e., Hamburg, Antwerp and Rotterdam. Special attention is paid to the relationships between the most important actors within the three port-city clusters. The complex relationships are operationalized by a set of newly developed sensitizing concepts. It is concluded that all three cases have unique shared values play that play a crucial role in the changing relationships between ports and cities. The nature and intensity of these shared values are responsible for the impact of the trends on the relationship between a certain port and its city. E.g., the bond between the port and the city is the strongest in Hamburg and based on a strong culture that strengthen the integration of between port and city in many domains of society. For Antwerp, the political constellation is responsible for a continuing presence in the development of the city and the port, but also of the surrounding smaller municipalities. In Rotterdam, a more business-oriented culture was introduced that replaced a culture of common interests. It is concluded that the three cases have in common that variations in shared values plays a crucial role in the changing relationships between port and city.</p

Living Apart Together: Rotterdam, Antwerp and Hamburg: relationships between port and city under pressure

Ports and port cities have been separated throughout the years as a result of global dynamics like increase in scale. This can be noticed all over the world but variation can be seen in the way these dynamics have been absorbed. This thesis researches the way the port cities Rotterdam, Antwerp and Hamburg have been dealing with these develoopments. Characteristics of various political economic systems have been distinguised as a possible explanation for the differences in outcome

Evolution of multicellularity by collective integration of spatial information

At the origin of multicellularity, cells may have evolved aggregation in response to predation, for functional specialisation or to allow large-scale integration of environmental cues. These group-level properties emerged from the interactions between cells in a group, and determined the selection pressures experienced by these cells. We investigate the evolution of multicellularity with an evolutionary model where cells search for resources by chemotaxis in a shallow, noisy gradient. Cells can evolve their adhesion to others in a periodically changing environment, where a cell's fitness solely depends on its distance from the gradient source. We show that multicellular aggregates evolve because they perform chemotaxis more efficiently than single cells. Only when the environment changes too frequently, a unicellular state evolves which relies on cell dispersal. Both strategies prevent the invasion of the other through interference competition, creating evolutionary bi-stability. Therefore, collective behaviour can be an emergent selective driver for undifferentiated multicellularity.Animal sciencesAnalysis and Stochastic

Systems Biology Approach Pinpoints Minimum Requirements for Auxin Distribution during Fruit Opening : Plant Systems Biology

The phytohormone auxin is implied in steering various developmental decisions during plant morphogenesis in a concentration-dependent manner. Auxin maxima have been shown to maintain meristematic activity, for example, of the root apical meristem, and position new sites of outgrowth, such as during lateral root initiation and phyllotaxis. More recently, it has been demonstrated that sites of auxin minima also provide positional information. In the developing Arabidopsis fruit, auxin minima are required for correct differentiation of the valve margin. It remains unclear, however, how this auxin minimum is generated and maintained. Here, we employ a systems biology approach to model auxin transport based on experimental observations. This allows us to determine the minimal requirements for its establishment. Our simulations reveal that two alternative processes—which we coin “flux-barrier” and “flux-passage”—are both able to generate an auxin minimum, but under different parameter settings. Both models are in principle able to yield similar auxin profiles but present qualitatively distinct patterns of auxin flux. The models were tested by tissue-specific inducible ablation, revealing that the auxin minimum in the fruit is most likely generated by a flux-passage process. Model predictions were further supported through 3D PIN localization imaging and implementing experimentally observed transporter localization. Through such an experimental–modeling cycle, we predict how the auxin minimum gradually matures during fruit development to ensure timely fruit opening and seed dispersal.Peer reviewe

Chemotactic migration of T cells towards dendritic cells promotes the detection of rare antigens

In many immunological processes chemoattraction is thought to play a role in guiding cells to their sites of action. However, based on in vivo two-photon microscopy experiments in the absence of cognate antigen, T cell migration in lymph nodes (LNs) has been roughly described as a random walk. Although it has been shown that dendritic cells (DCs) carrying cognate antigen in some circumstances attract T cells chemotactically, it is currently still unclear whether chemoattraction of T cells towards DCs helps or hampers scanning. Chemoattraction towards DCs could on the one hand help T cells to rapidly find DCs. On the other hand, it could be deleterious if DCs become shielded by a multitude of attracted yet non-specific T cells. Results from a recent simulation study suggested that the deleterious effect dominates. We re-addressed the question whether T cell chemoattraction towards DCs is expected to promote or hamper the detection of rare antigens using the Cellular Potts Model, a formalism that allows for dynamic, flexible cellular shapes and cell migration. Our simulations show that chemoattraction of T cells enhances the DC scanning efficiency, leading to an increased probability that rare antigenspecific T cells find DCs carrying cognate antigen. Desensitization of T cells after contact with a DC further improves the scanning efficiency, yielding an almost threefold enhancement compared to random migration. Moreover, the chemotaxisdriven migration still roughly appears as a random walk, hence fine-tuned analysis of cell tracks will be required to detect chemotaxis within microscopy data.Toxicolog

Unipolar distributions of junctional Myosin II identify cell stripe boundaries that drive cell intercalation throughout Drosophila axis extension.

Convergence and extension movements elongate tissues during development. Drosophila germ-band extension (GBE) is one example, which requires active cell rearrangements driven by Myosin II planar polarisation. A combinatorial code of Toll receptors downstream of pair-rule genes contributes to this polarization via local cell-cell interactions. We developed novel computational methods to analyse the spatiotemporal dynamics of Myosin II. We show that initial Myosin II bipolar cell polarization gives way to unipolar enrichment at parasegmental boundaries and two further boundaries within each parasegment, concomitant with a doubling of cell number as the tissue elongates. These boundaries are the primary sites of cell intercalation, behaving as mechanical barriers and providing a mechanism for how cells remain ordered during GBE. Enrichment at parasegment boundaries during GBE is independent of Wingless signaling, suggesting pair-rule gene control. We propose an updated cell-cell interaction model for Myosin II polarization that we tested in a vertex-based simulation

VDJdb in 2019: database extension, new analysis infrastructure and a T-cell receptor motif compendium

Here, we report an update of the VDJdb database with a substantial increase in the number of T-cell receptor (TCR) sequences and their cognate antigens. The update further provides a new database infrastructure featuring two additional analysis modes that facilitate database querying and real-world data analysis. The increased yield of TCR specificity identification methods and the overall increase in the number of studies in the field has allowed us to expand the database more than 5-fold. Furthermore, several new analysis methods are included. For example, batch annotation of TCR repertoire sequencing samples allows for annotating large datasets on-line. Using recently developed bioinformatic methods for TCR motif mining, we have built a reduced set of high-quality TCR motifs that can be used for both training TCR specificity predictors and matching against TCRs of interest. These additions enhance the versatility of the VDJdb in the task of exploring T-cell antigen specificities. The database is available at https://vdjdb.cdr3.net