Non-equilibrium coherence dynamics in one-dimensional Bose gases

Low-dimensional systems are beautiful examples of many-body quantum physics. For one-dimensional systems the Luttinger liquid approach provides insight into universal properties. Much is known of the equilibrium state, both in the weakly and strongly interacting regime. However, it remains a challenge to probe the dynamics by which this equilibrium state is reached. Here we present a direct experimental study of the coherence dynamics in both isolated and coupled degenerate 1d Bose gases. Dynamic splitting is used to create two 1d systems in a phase coherent state. The time evolution of the coherence is revealed in local phase shifts of the subsequently observed interference patterns. Completely isolated 1d Bose gases are observed to exhibit a universal sub-exponential coherence decay in excellent agreement with recent predictions by Burkov et al. [Phys. Rev. Lett. 98, 200404 (2007)]. For two coupled 1d Bose gases the coherence factor is observed to approach a non-zero equilibrium value as predicted by a Bogoliubov approach. This coupled-system decay to finite coherence is the matter wave equivalent of phase locking two lasers by injection. The non-equilibrium dynamics of superfluids plays an important role in a wide range of physical systems, such as superconductors, quantum-Hall systems, superfluid Helium, and spin systems. Our experiments studying coherence dynamics show that 1d Bose gases are ideally suited for investigating this class of phenomena.Comment: to appear in natur

Scientific Reports / The unfolded protein response impacts melanoma progression by enhancing FGF expression and can be antagonized by a chemical chaperone

The mechanisms hallmarking melanoma progression are insufficiently understood. Here we studied the impact of the unfolded protein response (UPR) - a signalling cascade playing ambiguous roles in carcinogenesis - in melanoma malignancy. We identified isogenic patient-derived melanoma cell lines harboring BRAFV600E-mutations as a model system to study the role of intrinsic UPR in melanoma progression. We show that the activity of the three effector pathways of the UPR (ATF6, PERK and IRE1) was increased in metastatic compared to non-metastatic cells. Increased UPR-activity was associated with increased flexibility to cope with ER stress. The activity of the ATF6- and the PERK-, but not the IRE-pathway, correlated with poor survival in melanoma patients. Using whole-genome expression analysis, we show that the UPR is an inducer of FGF1 and FGF2 expression and cell migration. Antagonization of the UPR using the chemical chaperone 4-phenylbutyric acid (4-PBA) reduced FGF expression and inhibited cell migration and viability. Consistently, FGF expression positively correlated with the activity of ATF6 and PERK in human melanomas. We conclude that chronic UPR stimulates the FGF/FGF-receptor signalling axis and promotes melanoma progression. Hence, the development of potent chemical chaperones to antagonize the UPR might be a therapeutic approach to target melanoma.(VLID)463730

Visions for nature and nature’s contributions to people for the 21st century : Report from an IPBES visioning workshop held on 4-8 September 2017 in Auckland, New Zealand

Existing scenarios of biodiversity and ecosystem services (BES) have important limitations and gaps that constrain their usefulness for the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES). Specifically, they fail to incorporate policy objectives related to nature conservation and social-ecological feedbacks, they do not address the linkages between biodiversity and ecosystem services, and they are typically relevant at only a particular spatial scale. In addition, nature and its benefits are treated as the consequence of human decisions, but are not at the centre of the analysis. To address these issues, the IPBES Scenarios and Models Expert Group initiated the development of a set of Multiscale Scenarios for Nature Futures based on positive visions for human relationships with nature.The first step of this process was a visioning workshop with stakeholders and experts on 4-8 September 2017 in Auckland, New Zealand. A total of 73 participants from inter-governmental organisations, national government organisations, non-governmental organisations, academia and the private sector, from 31 countries, and with a range of sectoral expertise on biodiversity topics, from urban development to agriculture to fisheries, worked together in a visioning exercise. This report documents the results from this visioning workshop to inform further stakeholder consultation and the development of the associated multiscale scenarios by modelers and experts. This creative visioning exercise was carried out in four steps based on a suite of participatory methods that were used to develop visions of alternative futures. First the participants identified important themes to develop the visions. Next, thematic groups identified the main trends for BES in each theme and a set of “Seeds” of emerging initiatives leading to positive futures for our relationship with nature. Implications of what would happen across a range of sectors were identified for each seed. Then a pathway analysis of how the current regime in each theme may be transformed into the future desirable regime was carriedout. Narratives were then built for the visions emerging from each group. Finally, commonalities of visions across the groups were identified, and the regional relevance of each vision for different parts of the world was assessed

Visions for nature and nature’s contributions to people for the 21st century : Report from an IPBES visioning workshop held on 4-8 September 2017 in Auckland, New Zealand

Existing scenarios of biodiversity and ecosystem services (BES) have important limitations and gaps that constrain their usefulness for the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES). Specifically, they fail to incorporate policy objectives related to nature conservation and social-ecological feedbacks, they do not address the linkages between biodiversity and ecosystem services, and they are typically relevant at only a particular spatial scale. In addition, nature and its benefits are treated as the consequence of human decisions, but are not at the centre of the analysis. To address these issues, the IPBES Scenarios and Models Expert Group initiated the development of a set of Multiscale Scenarios for Nature Futures based on positive visions for human relationships with nature.The first step of this process was a visioning workshop with stakeholders and experts on 4-8 September 2017 in Auckland, New Zealand. A total of 73 participants from inter-governmental organisations, national government organisations, non-governmental organisations, academia and the private sector, from 31 countries, and with a range of sectoral expertise on biodiversity topics, from urban development to agriculture to fisheries, worked together in a visioning exercise. This report documents the results from this visioning workshop to inform further stakeholder consultation and the development of the associated multiscale scenarios by modelers and experts. This creative visioning exercise was carried out in four steps based on a suite of participatory methods that were used to develop visions of alternative futures. First the participants identified important themes to develop the visions. Next, thematic groups identified the main trends for BES in each theme and a set of “Seeds” of emerging initiatives leading to positive futures for our relationship with nature. Implications of what would happen across a range of sectors were identified for each seed. Then a pathway analysis of how the current regime in each theme may be transformed into the future desirable regime was carriedout. Narratives were then built for the visions emerging from each group. Finally, commonalities of visions across the groups were identified, and the regional relevance of each vision for different parts of the world was assessed

Abstracts of the 6th FECS Conference 1998 Lectures

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