A 380 GHz SIS receiver using Nb/AlO(x)/Nb junctions for a radioastronomical balloon-borne experiment: PRONAOS

The superheterodyne detection technique used for the spectrometer instrument of the PRONAOS project will provide a very high spectral resolution (delta nu/nu = 10(exp -6)). The most critical components are those located at the front-end of the receiver: their contribution dominates the total noise of the receiver. Therefore, it is important to perform accurate studies for specific components, such as mixers and multipliers working in the submillimeter wave range. Difficulties in generating enough local oscillator (LO) power at high frequencies make SIS mixers very desirable for operation above 300 GHz. The low LO power requirements and the low noise temperature of these mixers are the primary reason for building an SIS receiver. This paper reports the successful fabrication of small (less than or equal to 1 sq micron) Nb/Al-O(x)/Nb junctions and arrays with excellent I-V characteristics and very good reliability, resulting in a low noise receiver performance measured in the 368/380 GHz frequency range

Teaching powerful geographical knowledge : a matter of social justice : initial findings from the GeoCapabilities 3 project

GeoCapabilities offers an approach for unlocking powerful disciplinary knowledge (PDK) for children. In phase three of the project, we are exploring how far GeoCapabilities ‘works’ for teachers serving communities in challenging socio-economic circumstances. We connect GeoCapabilities to social justice in education, theoretically. Then, using the topic of migration, we discuss initial empirical findings of how teachers understand PDK and their challenges for teaching PDK. Collaborative work between teachers and academics suggests that the social justice dimension of GeoCapabilities could be realised, with appropriate support for teachers. We conclude with a set of principles to inform the future work of GeoCapabilities

Climate change-induced disasters and cultural heritage: Optimizing management strategies in Central Europe

Due to climate change, it is foreseen that the frequency and magnitude of extreme climate events such as heavy precipitation, flooding and drought will increase throughout Europe. In recent times, numerous areas suffered from disasters that produced significant damage to cultural heritage. Although different risk management strategies are currently enforced in Central Europe, there still exist many challenges that undermine their effectiveness. This study reviews the necessary points to be addressed for strengthening existing management strategies within the region and the characteristics of potential resilience building measures. It presents feasible and tailored ICT solutions (e.g. a web GIS platform) and decision support tools (e.g. a manual for cultural heritage resilience and a handbook on transnational rescue procedures) for the protection of cultural heritage against floods, heavy rain and fire. These tools result from the Interreg Central Europe project ProteCHt2save, concentrating on risk assessment and sustainable protection of cultural heritage in changing environments. The proposed measures are tested at pilot sites and successfully integrated in local risk management plans. Future work is also proposed for further implementation of the results

Relations as executable specifications: taming partiality and non-determinism using invariants

Comunicação publicada em "Lecture Notes in Computer Science", vol. 7560 (2012), pag. 146-161The calculus of relations has been widely used in program specification and reasoning. It is very tempting to use such specifications as running prototypes of the desired program, but, even considering finite domains, the inherent partiality and non-determinism of relations makes this impractical and highly inefficient. To tame partiality we prescribe the usage of invariants, represented by coreflexives, to characterize the exact domains and codomains of relational specifications. Such invariants can be used as pre-condition checkers to avoid runtime errors. Moreover, we show how such invariants can be used to narrow the non-deterministic execution of relational specifications, making it viable for a relevant class of problems. In particular, we show how the proposed techniques can be applied to execute specifications of bidirectional transformations, a domain where partiality and non-determinism are paramount.Fundação para a Ciência e a Tecnologi

Implementing Encapsulated Search for a Lazy Functional Logic Language

Abstract. A distinguishing feature of logic and functional logic lan-guages is their ability to perform computations with partial data and to search for solutions of a goal. Having a built-in search strategy is convenient but not always sufficient. For many practical applications the built-in search strategy (usually depth-first search via global back-tracking) is not well suited. Also the non-deterministic instantiation of unbound logic variables conflicts with the monadic I/O concept, which requires a single-threaded use of the world. A solution to these problems is to encapsulate search via a primitive operator try, which returns all possible solutions to a search goal in a list. In the present paper we develop an abstract machine that aims at an efficient implementation of encapsulated search in a lazy functional logic language.

ISOCAM OBSERVATIONS OF M31

Abstract We present ISOCAM images of the Andromeda galaxy center. They display an elliptical stellar bulge and a more complexe dust distribution. The spatial dust distribution follows a mini-spiral structure identical to the distribution of absorption in optical wavelengths. A discussion on the nature of the dust from CVF observations is also presented. The central part and the molecular ring of M31 are excellent targets for FIRST

Phase transitions for suspension flows

This paper is devoted to study thermodynamic formalism for suspension flows defined over countable alphabets. We are mostly interested in the regularity properties of the pressure function. We establish conditions for the pressure function to be real analytic or to exhibit a phase transition. We also construct an example of a potential for which the pressure has countably many phase transitions.Comment: Example 5.2 expanded. Typos corrected. Section 6.1 superced the note "Thermodynamic formalism for the positive geodesic flow on the modular surface" arXiv:1009.462

Enhanced ionization of acetylene in intense laser pulses is due to energy upshift and field coupling of multiple orbitals

Synopsis We describe a new enhanced ionization mechanism for polyatomic molecules. It works via a significant energy up-shift of valence orbitals for stretched bonds and a strong concomitant increase in the coupling between multiple molecular orbitals

Microscopic observation of magnon bound states and their dynamics

More than eighty years ago, H. Bethe pointed out the existence of bound states of elementary spin waves in one-dimensional quantum magnets. To date, identifying signatures of such magnon bound states has remained a subject of intense theoretical research while their detection has proved challenging for experiments. Ultracold atoms offer an ideal setting to reveal such bound states by tracking the spin dynamics after a local quantum quench with single-spin and single-site resolution. Here we report on the direct observation of two-magnon bound states using in-situ correlation measurements in a one-dimensional Heisenberg spin chain realized with ultracold bosonic atoms in an optical lattice. We observe the quantum walk of free and bound magnon states through time-resolved measurements of the two spin impurities. The increased effective mass of the compound magnon state results in slower spin dynamics as compared to single magnon excitations. In our measurements, we also determine the decay time of bound magnons, which is most likely limited by scattering on thermal fluctuations in the system. Our results open a new pathway for studying fundamental properties of quantum magnets and, more generally, properties of interacting impurities in quantum many-body systems.Comment: 8 pages, 7 figure