3,584 research outputs found

    Cooperating Distributed Grammar Systems of Finite Index Working in Hybrid Modes

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    We study cooperating distributed grammar systems working in hybrid modes in connection with the finite index restriction in two different ways: firstly, we investigate cooperating distributed grammar systems working in hybrid modes which characterize programmed grammars with the finite index restriction; looking at the number of components of such systems, we obtain surprisingly rich lattice structures for the inclusion relations between the corresponding language families. Secondly, we impose the finite index restriction on cooperating distributed grammar systems working in hybrid modes themselves, which leads us to new characterizations of programmed grammars of finite index.Comment: In Proceedings AFL 2014, arXiv:1405.527

    Spontaneous symmetry breaking of charge-regulated surfaces

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    The interaction between two chemically identical charge-regulated surfaces is studied using the classical density functional theory. In contrast to common expectations and assumptions, under certain realistic conditions we find a spontaneous emergence of disparate charge densities on the two surfaces. The surface charge densities can differ not only in their magnitude, but quite unexpectedly, even in their sign, implying that the electrostatic interaction between the two chemically identical surfaces can be attractive instead of repulsive. Moreover, an initial symmetry with equal charge densities on both surfaces can also be broken spontaneously upon decreasing the separation between the two surfaces. The origin of this phenomenon is a competition between the adsorption of ions from the solution to the surface and the interaction between the adsorbed ions already on the surface.These findings are fundamental for the understanding of the forces between colloidal objects and, in particular, they are bound to strongly influence the present picture of protein interaction.Comment: 19 pages, 5 figure

    Immobilisation, restricted spatial mobility and displacement in violent conflict: Humanitarian needs of confined communities in Colombia

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    Putting the humanitarian-development nexus into practice, aid organisations and donors pay most attention to camp populations in protracted refugee situations (PRS). This Paper argues that synergies arise when development aid redefines and expands the area of humanitarian needs regarding developmental objectives and instruments rather than bolstering the mainstream activities of humanitarian actors. Drawing on the case of Colombia, the argument of this Paper is threefold: First, it shows how the conditions to qualify refugees and IDPs as aid recipients must be extended to include forcibly immobilised persons. The Paper understands 'forcibly immobilised persons' as individuals who are forced to stay in the same place for lack of alternatives or constraints on their movement (e.g. through armed groups). Strikingly, forcibly immobilised persons have so far usually been overlooked as persons in need, although they face similar hardships as refugees and internally displaced persons (IDPs). This is why this Paper proposes to replace the classical concept of spatial displacement with a model of displacement that includes both in situ immobilised persons (on the spot) and ex situ immobilised persons (immobilised after initial spatial movement). Second, the Paper argues that individual needs, such as the need for protection, rather than circumstances, should be decisive for aid eligibility. Whether a situation is categorised as "war", for instance, is a highly politicised question and hence not a reliable indicator - whereas a needs-based approach is. Third, the Paper draws on an in-depth analysis of confined communities in Colombia to show that forcibly immobilised persons - like IDPs and refugees - often require humanitarian and development aid, thus showing clear examples for how the nexus could work - as it already does in part. Overall, this Paper thus proposes a reconceptualisation of the humanitarian-development nexus to ensure a more targeted reach for persons in need

    Talking at cross-purposes? On ambiguous relationships between international policies on return and reintegration and their local conceptualisations in Ghana, the Gambia and Senegal

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    This Working Paper explores and compares return to and reintegration in Ghana, the Gambia and Senegal while setting different positionalities of migrants against migration and return regimes and broader socio-economic inequalities. The Paper first highlights the trajectories and motivations of migrants and returnees, including a group-centred perspective on the continuous relevance of relations with the communities of origin. Then, it relates migrant journeys to diverging national political economies and policies. Differing return policies on the one hand and conflicting interests and expectations of the involved actors on the other create unequal options and expectations of mobility. The case studies show that diverging experiences of return, thus, not only depend on the individual situations, such as differences in age, gender, legal status or social class, but also the broader social context, the existing economic situation - and finally the politicised relations and interests between stakeholders in the migration and return processes. The findings on circular mobility and division of labour respectively widen the perspective on return and reintegration policies, wich have traditionally been shaped by a uni-linear uni-directional bias

    Conceptualising crisis, refugees and IDPs: insights from northern Iraq on vulnerabilities and needs caused by displacement

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    This Working Paper assesses how humanitarian and development aid agencies address individuals whose human rights and human dignity have been affected by displacement. It proposes a fresh look at how to measure needs that arise in such situations. To this end, the Paper evaluates characteristic needs regarding livelihoods, rights and basic services for displaced persons in an empirical study of so-called protracted refugee situations (PRS). The needs are then contrasted with the international legal category of ‘refugee’ and the descriptive definition of internally displaced persons (IDPs) used by aid agencies to address situations of displacement. Following empirical observations and drawing from existing models, the study establishes an inter-subjectively comprehensible catalogue of needs, i.e. land, employment (livelihoods), housing, social inclusion, nutrition, health, community assets, social networks, education, legal aid, political rights, legal documents, human rights. It is argued that these indicators need to be evaluated in regard to the degree of access displaced persons have (from no access to full access). The weighted indicators establish different points of reference to measure the detrimental impact of displacement on human dignity. Assessment of aid for displaced persons thereby reaches beyond the pre-displacement situation as a central point of reference: This would enable humanitarian and development actors to evaluate their contribution to facilitating a dignified life of individuals more accurately, as a return to the status quo ante does not automatically mean that aid was successful—e.g. a return to misery. Drawing on field research findings in northern Iraq, moreover, the Paper argues that any indicator-based-approach must be combined with an analysis of the socio-political and historical context of forced migration and also pay attention to impacts on the host society. In line with empirical examples, the Working Paper argues that humanitarian and development aid agencies need to start from a long-term, multi-sectoral, whole-of-society, and systematically indicatorbased approach—even though it is inevitable to prioritise some issues (and disregard others) in situations of crisis

    (Tissue) P Systems Using Non-cooperative Rules Without Halting Conditions

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    We consider (tissue) P systems using non-cooperative rules, but considering computations without halting conditions. As results of a computation we take the contents of a specified output membrane/cell in each derivation step, no matter whether this computation will ever halt or not, eventually taking only results completely consisting of terminal objects only. The computational power of (tissue) P systems using non-cooperative rules turns out to be equivalent to that of (E)0L systems

    دوافع التنقُّل في النزوح طويل الأمد: حالة انتقال الإرتيريُّين والكونغوِيُّين: Mobility dynamics in protracted displacement: Eritreans and Congolese on the move

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    يجد ملايين الإرتيريين والكونغويين أنفسهم اليوم في حالات نزوح طويل الأمد. لذا، فإن الفهم الدقيق لكيفية تأثير التنقل البدني والاجتماعي على حياتهم اليومية هو أمرٌ في غاية الأهمية من أجل ايجاد تدخُّلات أكثر فاعلية مُعدَّة لهذه الغاية. Millions of Eritreans and Congolese find themselves in situations of protracted displacement. A more nuanced understanding of how physical and social mobility affects their daily lives is crucial to developing more effective tailor-made interventions

    Beyond aid: The continuous struggle to cope with displacement in Myanmar and Thailand

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    Multi-party elections and the signing of a Nationwide Ceasefire Agreement (NCA) in 2015 raised hopes in the international community of a possible settlement of Myanmar’s protracted conflict and one of the world’s worst protracted displacement situations (PDS) in the near future. Yet conflicts in the border areas and human rights abuses carry on, more than 600,000 Burmese continue to be displaced within Myanmar and three to five million remain in Thailand. This Working Paper examines strategies that displaced persons from Myanmar have developed striving to cope with major challenges of displacement. We observed that strategies go beyond the commonly used three durable solutions. The findings suggest that neither return nor local integration into the society of the host country is necessarily definite or are mutually exclusive. Both are merely two poles of a wide range of displaced persons’ possible coping strategies, encompassing return, cyclical movements, temporary return, de jure local integration and different levels and stages of de facto local integration. In scrutinizing whether the change of governance eradicated the causes of displacement, brought peace and laid the foundation for return, our research revealed significant flaws in Myanmar’s political transition. Notwithstanding impressive achievements, conflicts persist and are likely to cause new waves of displacement. With regard to access to legal, economic, political rights, services, house, land, property and livelihoods, the situation of displaced persons (DPs) remains dire. Still, the international community promotes return and has been reducing assistance for camps in and outside of Myanmar. For internally displaced persons (IDPs) and refugees, this means that options of refuge have diminished, while the causes to flee remain. After decades of displacement, DPs have developed a set of practices such as diversifications of livelihoods, income sources, residences, and others. We argue that it is imperative for any long-term and coherent strategy that addresses protracted displacement to take those micro realities into account
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