Proximity DC squids in the long junction limit

We report the design and measurement of Superconducting/normal/superconducting (SNS) proximity DC squids in the long junction limit, i.e. superconducting loops interrupted by two normal metal wires roughly a micrometer long. Thanks to the clean interface between the metals, at low temperature a large supercurrent flows through the device. The dc squid-like geometry leads to an almost complete periodic modulation of the critical current through the device by a magnetic flux, with a flux periodicity of a flux quantum h/2e through the SNS loop. In addition, we examine the entire field dependence, notably the low and high field dependence of the maximum switching current. In contrast with the well-known Fraunhoffer-type oscillations typical of short wide junctions, we find a monotonous gaussian extinction of the critical current at high field. As shown in [15], this monotonous dependence is typical of long and narrow diffusive junctions. We also find in some cases a puzzling reentrance at low field. In contrast, the temperature dependence of the critical current is well described by the proximity effect theory, as found by Dubos {\it et al.} [16] on SNS wires in the long junction limit. The switching current distributions and hysteretic IV curves also suggest interesting dynamics of long SNS junctions with an important role played by the diffusion time across the junction.Comment: 12 pages, 16 figure

Análisis de preferencias turísticas: un enfoque innovador

Most of the decisions concerning tourism are made in a context of uncertainty, and on several occasions the consequences of the choice are not known with certainty, or even there is missing information on this matter. For these reasons, the fuzzy set theory is an appropriate tool for their treatments.In this paper we show, through a case study, an alternative model for the analysis of tourist preferences of a segment of individuals based on the concept of fuzzy consideration set.La mayor parte de las decisiones referidas a turismo se toman en un contexto de incertidumbre, y en muchas oportunidades no se conocen con certeza las consecuencias de la elección, ni se posee toda la información. Por estas razones la teoría de conjuntos borrosos resulta una herramienta apropiada para su tratamiento.En este trabajo se presenta, a través del estudio de un caso, un modelo alternativo para el análisis de las preferencias turísticas, de un segmento de individuos, basado en el concepto de conjunto de consideración borroso

Comment on Qian et al. 2008: La Niña and El Niño composites of atmospheric CO2 change

It is well known that interannual extremes in the rate of change of atmospheric CO2 are strongly influenced by the occurrence of El Niño-Southern Oscillation (ENSO) events. Qian et al. presented ENSO composites of atmospheric CO2 changes. We show that their composites do not reflect the atmospheric changes that are most relevant to understanding the role of ENSO on atmospheric CO2 variability. We present here composites of atmospheric CO2 change that differ markedly from those of Qian et al., and reveal previously unreported asymmetries between the effects on the global carbon system of El Niño and La Niña events. The calendar-year timing differs; La Niña changes in atmospheric CO2 typically occur primarily over September–May, while El Niño changes occur primarily over December–August. And the net concentration change is quite different; La Niña changes are about half the size of El Niño changes. These results illustrate new aspects of the ENSO/global carbon budget interaction and provide useful global-scale benchmarks for the evaluation of Earth System Model studies of the carbon system

Intraoperative probe detecting β− decays in brain tumour radio-guided surgery

Abstract Radio-guided surgery (RGS) is a technique to intraoperatively detect tumour remnants, favouring a radical resection. Exploiting β − emitting tracers provides a higher signal to background ratio compared to the established technique with γ radiation, allowing the extension of the RGS applicability range. We developed and tested a detector based on para-terphenyl scintillator with high sensitivity to low energy electrons and almost transparent to γ s to be used as intraoperative probe for RGS with β − emitting tracer. Portable read out electronics was customised to match the surgeon needs. This probe was used for preclinical test on specific phantoms and a test on "ex vivo" specimens from patients affected by meningioma showing very promising results for the application of this new technique on brain tumours. In this paper, the prototype of the intraoperative probe and the tests are discussed; then, the results on meningioma are used to make predictions on the performance of the probe detecting residuals of a more challenging and more interesting brain tumour: the glioma

The Megapixel EBCCD: a high-resolution imaging tube sensitive to single photons

A hybrid image-intensifier tube, suitable for extremely low-light imaging, has been tested. This device is based on an Electron-Bombarded CCD chip (EBCCD) with $1024 \times 1024$ sensitive pixe ls. The tube, which has a photocathode diameter of 40 mm, is gateable and zoomable, with an image magnification varying from 0.62 to 1.3. The high gain (about 4000 collected electrons per photo electron at the operational voltage of 15 kV) and the relatively low noise (180 electrons per pixel at 10 MHz pixel-readout frequency), allows single-photoelectron signals to be separated from n oise with a signal-to-noise ratio greater than 10. By applying an appropriate threshold on the signal amplitude, the background can almost be eliminated, with a loss of few percent in single-ph otoelectron counting. High inner gain, low noise, single-photoelectron sensitivity, and high spatial resolution make the EBCCD imaging tube a unique device, attractive for many applications in h igh-energy physics, astrophysics, biomedical diagnostics

Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison.

Recent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns. The output of this process is a scenario framework exploring where the region is headed rather than how to achieve its goals, extrapolating its current policy efforts into the future. We find that Europe is currently on track to overperforming its pre-2020 40% target yet far from its newest ambition of 55% emissions cuts by 2030, as well as looking at a 1.0-2.35 GtCO2 emissions range in 2050. Aside from the importance of transport electrification, deployment levels of carbon capture and storage are found intertwined with deeper emissions cuts and with hydrogen diffusion, with most hydrogen produced post-2040 being blue. Finally, the multi-model exercise has highlighted benefits from deeper decarbonisation in terms of energy security and jobs, and moderate to high renewables-dominated investment needs