Dynamical Casimir effect in superconducting circuits: a numerical approach

We present a numerical analysis of the particle creation for a quantum field in the presence of time dependent boundary conditions. Having in mind recent experiments involving superconducting circuits, we consider their description in terms of a scalar field in a one dimensional cavity satisfying generalized boundary conditions that involve a time-dependent linear combination of the field and its spatial and time derivatives. We evaluate numerically the Bogoliubov transformation between {\it in} and {\it out}-states and find that the rate of particle production strongly depends on whether the spectrum of the unperturbed cavity is equidistant or not, and also on the amplitude of the temporal oscillations of the boundary conditions. We provide analytic justifications for the different regimes found numerically.Comment: 20 pages. 11 figure

Key policy questions for ex-ante impact assessment of European agricultural and rural policies

Policies in the agricultural and rural sectors are of key importance in shaping their sustainable development. These policies are changing from market-based policies to policies that aim to influence farmers' decision-making. Thus, the scientific literature supporting evidence-based policy-making must develop models that simulate individual decision-making (IDM) by farmers. This study aims to understand key policy objectives, related policy questions and benchmark scenarios relevant to the European agricultural sector to define the research agenda for a suite of IDM models. This research goal has been addressed following a five-step process that involved different research tools and heterogeneous actors, including key stakeholders. Results suggest that environmental policy objectives are the most relevant for European agriculture in the coming decades. Thus, the scenario modelling exercise should focus mainly on the agri-environmental policies' impacts while properly considering the potential trade-offs between economic and environmental objectives

How natural capital delivers ecosystem services: A typology derived from a systematic review

There is no unified evidence base to help decision-makers understand how the multiple components of natural capital interact to deliver ecosystem services. We systematically reviewed 780 papers, recording how natural capital attributes (29 biotic attributes and 11 abiotic factors) affect the delivery of 13 ecosystem services. We develop a simple typology based on the observation that five main attribute groups influence the capacity of natural capital to provide ecosystem services, related to: A) the physical amount of vegetation cover; B) presence of suitable habitat to support species or functional groups that provide a service; C) characteristics of particular species or functional groups; D) physical and biological diversity; and E) abiotic factors that interact with the biotic factors in groups A-D. ` Bundles' of services can be identified that are governed by different attribute groups. Management aimed at maximising only one service often has negative impacts on other services and on biological and physical diversity. Sustainable ecosystem management should aim to maintain healthy, diverse and resilient ecosystems that can deliver a wide range of ecosystem services in the long term. This can maximise the synergies and minimise the trade-offs between ecosystem services and is also compatible with the aim of conserving biodiversity. (C) 2017 Elsevier B.V. All rights reserved

Finite element analysis and material sensitivity of Peltier thermoelectric cells coolers

In this work, a finite element simulation of a commercial thermoelectric cell, working as a cooling heat pump, is presented. The specially developed finite element is three-dimensional, non-linear in its formulation (using quadratic temperature-dependence on material properties) and fully coupled, including the Seebeck, Peltier, Thomson and Joule effects. Another special interface finite element is developed to prescribe the electric intensity, taking advantage of repetitions and symmetries. A thorough study of the distributions of voltage, temperature and the corresponding fluxes is presented, and the performance of the cell is compared with that of the manufacturer and with simplified analytical formulations, showing a good agreement. Combining the finite element model with the Monte Carlo technique, a sensitivity analysis is presented to take into account the performance dependence on the material properties, geometrical parameters and prescribed values. This analysis, which can be considered a first step to optimize these devices, concludes that the temperature-dependence of the material properties of electric conductivity and Seebeck coefficient is very relevant on cell performance.This research was partially supported by the Ministry of Education through Grant FPU AP-2006-02372 and also from Grants MICINN BIA-2008-00522, MCyT DPI 2002-04472-C02-02 and Excelencia Junta Andalucia P08-TEP-3641.Pérez-Aparicio, JL.; Palma, R.; Taylor, R. (2012). Finite element analysis and material sensitivity of Peltier thermoelectric cells coolers. International Journal of Heat and Mass Transfer. 55(4):1363-1374. https://doi.org/10.1016/j.ijheatmasstransfer.2011.08.031S1363137455

Ret receptor tyrosine kinase sustains proliferation and tissue maturation in intestinal epithelia.

Expression of the Ret receptor tyrosine kinase is a defining feature of enteric neurons. Its importance is underscored by the effects of its mutation in Hirschsprung disease, leading to absence of gut innervation and severe gastrointestinal symptoms. We report a new and physiologically significant site of Ret expression in the intestine: the intestinal epithelium. Experiments in Drosophila indicate that Ret is expressed both by enteric neurons and adult intestinal epithelial progenitors, which require Ret to sustain their proliferation. Mechanistically, Ret is engaged in a positive feedback loop with Wnt/Wingless signalling, modulated by Src and Fak kinases. We find that Ret is also expressed by the developing intestinal epithelium of mice, where its expression is maintained into the adult stage in a subset of enteroendocrine/enterochromaffin cells. Mouse organoid experiments point to an intrinsic role for Ret in promoting epithelial maturation and regulating Wnt signalling. Our findings reveal evolutionary conservation of the positive Ret/Wnt signalling feedback in both developmental and homoeostatic contexts. They also suggest an epithelial contribution to Ret loss-of-function disorders such as Hirschsprung disease

How Personal Judgment Influences Scenario Development: an Example for Future Rural Development in Europe

Scenarios of alternative plausible futures have been used extensively to explore the potential effects of socioeconomic and environmental change. The ultimate objective of any explorative scenario exercise is to assess the variation in possible futures to provide insights into the range of potential outcomes. These results provide stakeholders with guidance for policy development, planning, and management. We explore how personal judgment can influence scenario development. Scenarios for the future of European rural regions are used to explore alternative outcomes under a public interventionist future and a market liberalization oriented future. A transparent qualitative framework is used to identify differences in outcomes based on personal judgment. Results show that, for both scenarios, there are plausible mechanisms that can lead to similar positive or negative outcomes. Choosing a single process per scenario, based on personal judgment and interpretation, can therefore greatly influence scenario outcomes and limit the range of uncertainty that is covered by the scenarios. The exercise shows the importance of making these judgments explicit in scenario development, especially when exploring broad consequences of alternative policy directions that may be based in political worldviews

Lymphovascular and perineural invasion as selection criteria for adjuvant therapy in intrahepatic cholangiocarcinoma: a multi-institution analysis

AbstractObjectivesCriteria for the selection of patients for adjuvant chemotherapy in intrahepatic cholangiocarcinoma (IHCC) are lacking. Some authors advocate treating patients with lymph node (LN) involvement; however, nodal assessment is often inadequate or not performed. This study aimed to identify surrogate criteria based on characteristics of the primary tumour.MethodsA total of 58 patients who underwent resection for IHCC between January 2000 and January 2010 at any of three institutions were identified. Primary outcome was overall survival (OS).ResultsMedian OS was 23.0months. Median tumour size was 6.5cm and the median number of lesions was one. Overall, 16% of patients had positive margins, 38% had perineural invasion (PNI), 40% had lymphovascular invasion (LVI) and 22% had LN involvement. A median of two LNs were removed and a median of zero were positive. Lymph nodes were not sampled in 34% of patients. Lymphovascular and perineural invasion were associated with reduced OS [9.6months vs. 32.7months (P= 0.020) and 10.7months vs. 32.7months (P= 0.008), respectively]. Lymph node involvement indicated a trend towards reduced OS (10.7months vs. 30.0months; P= 0.063). The presence of either LVI or PNI in node-negative patients was associated with a reduction in OS similar to that in node-positive patients (12.1months vs. 10.7months; P= 0.541). After accounting for adverse tumour factors, only LVI and PNI remained associated with decreased OS on multivariate analysis (hazard ratio4.07, 95% confidence interval 1.60–10.40; P= 0.003).ConclusionsLymphovascular and perineural invasion are separately associated with a reduction in OS similar to that in patients with LN-positive disease. As nodal dissection is often not performed and the number of nodes retrieved is frequently inadequate, these tumour-specific factors should be considered as criteria for selection for adjuvant chemotherapy