763 research outputs found
Advanced Concepts in Josephson Junction Reflection Amplifiers
Low-noise amplification atmicrowave frequencies has become increasingly
important for the research related to superconducting qubits and
nanoelectromechanical systems. The fundamental limit of added noise by a
phase-preserving amplifier is the standard quantum limit, often expressed as
noise temperature . Towards the goal of the
quantum limit, we have developed an amplifier based on intrinsic negative
resistance of a selectively damped Josephson junction. Here we present
measurement results on previously proposed wide-band microwave amplification
and discuss the challenges for improvements on the existing designs. We have
also studied flux-pumped metamaterial-based parametric amplifiers, whose
operating frequency can be widely tuned by external DC-flux, and demonstrate
operation at pumping, in contrast to the typical metamaterial
amplifiers pumped via signal lines at .Comment: 9 pages, 6 figure
Assessing urban system vulnerabilities to flooding to improve resilience and adaptation in spatial planning
Fluvial, pluvial and coastal flooding are the most frequent and costly natural hazard. Cities are social hubs and life in cities is reliant on a number of services and functions such as housing, healthcare, education and other key daily facilities. Urban flooding can cause significant disruption to these services and wider impacts on the population. These impacts may be short or long with a variably spatial scale: urban systems are spatially distributed and the nature of this can have significant effects on flood impacts. From an urban-planning perspective, measuring this disruption and its consequences is fundamental in order to develop more resilient cities. Whereas the assessment of physical vulnerabilities and direct damages is commonly addressed, new methodologies for assessing the systemic vulnerability and indirect damages at the urban scale are required. The proposed systemic approach recognizes the city as a collection of sub-systems or functional units (such as neighborhoods and suburbs), interconnected through the road network, providing key daily services to inhabitants (e.g., healthcare facilities, schools, food shops, leisure and cultural services). Each city is part of broader systems—which may or may not match administrative boundaries—and, as such, needs to be connected to its wider surroundings in a multi-scalar perspective. The systemic analysis, herein limited to residential households, is based on network-accessibility measures and evaluates the presence, the distribution among urban units and the redundancy of key daily services. Trying to spatially sketch the existence of systemic interdependences between neighborhoods, suburbs and municipalities, the proposed method highlights how urban systemic vulnerability spreads beyond the flooded areas. The aim is to understand which planning patterns and existing mixed-use developments are more flood resilient, thereby informing future urban development and regeneration projects. The methodology has been developed based on GIS and applied to an Italian municipality (Noale) in the metropolitan area of Venice, NE Italy
Recombinant factorVIII Fc fusion protein for the prevention and treatment of bleeding in children with severe hemophilia A
This work was supported
by funding from Biogen, including funding for the
editorial and writing support in the the development of
this paper
Preface and keynote’s talk of the Workshop on Social Interaction-based Recommendation (SIR 2018)
This paper summarises all the topics discussed by the invited talk Prof. Gabriella Pasi, during the first edition of the SIR: Workshop on Social Interaction-based Recommendation-The hosted by the 27th International Conference on Information and Knowledge Management (CIKM 2018) - October 22 2018, Turin (Italy)
Using an ensemble of features for personalized recommendations of scientific publications
Maintaining reviews of scientific publications as soon as new relevant publications are available is a typical challenge to many research communities. We address this challenge as a content-based recommendation problem, where the publications already selected for a review drive the recommendation of the new publications. In addition, resources such as domain databases, ontologies and academic graphs provide structured information about publications (e.g., authors, journals, conferences). Our experiments show that a simple model based on that structured information to represent publications achieve high precision and recall, and outperform models that use more sophisticated representations based on embeddings
A matter of words: NLP for quality evaluation of Wikipedia medical articles
Automatic quality evaluation of Web information is a task with many fields of
applications and of great relevance, especially in critical domains like the
medical one. We move from the intuition that the quality of content of medical
Web documents is affected by features related with the specific domain. First,
the usage of a specific vocabulary (Domain Informativeness); then, the adoption
of specific codes (like those used in the infoboxes of Wikipedia articles) and
the type of document (e.g., historical and technical ones). In this paper, we
propose to leverage specific domain features to improve the results of the
evaluation of Wikipedia medical articles. In particular, we evaluate the
articles adopting an "actionable" model, whose features are related to the
content of the articles, so that the model can also directly suggest strategies
for improving a given article quality. We rely on Natural Language Processing
(NLP) and dictionaries-based techniques in order to extract the bio-medical
concepts in a text. We prove the effectiveness of our approach by classifying
the medical articles of the Wikipedia Medicine Portal, which have been
previously manually labeled by the Wiki Project team. The results of our
experiments confirm that, by considering domain-oriented features, it is
possible to obtain sensible improvements with respect to existing solutions,
mainly for those articles that other approaches have less correctly classified.
Other than being interesting by their own, the results call for further
research in the area of domain specific features suitable for Web data quality
assessment
Evidence of magnetic accretion in an SW Sex star: discovery of variable circular polarization in LS Pegasi
We report on the discovery of variable circular polarization in the SW Sex
star LS Pegasi. The observed modulation has an amplitude of ~0.3 % and a period
of 29.6 minutes, which we assume as the spin period of the magnetic white
dwarf. We also detected periodic flaring in the blue wing of Hbeta, with a
period of 33.5 minutes. The difference between both frequencies is just the
orbital frequency, so we relate the 33.5-min modulation to the beat between the
orbital and spin period. We propose a new accretion scenario in SW Sex stars,
based on the shock of the disk-overflown gas stream against the white dwarf's
magnetosphere, which extends to the corotation radius. From this geometry, we
estimate a magnetic field strength of B(1) ~ 5-15 MG. Our results indicate that
magnetic accretion plays an important role in SW Sex stars and we suggest that
these systems are probably Intermediate Polars with the highest mass accretion
rates.Comment: Accepted by ApJ Letters. LaTeX, 14 pages, 3 PostScript figure
Fuzzy XPath : using fuzzy logic and IR features to approximately query XML documents
XML has become a key technology for interoperability, providing a common data model to applications. However, diverse data modeling choices may lead to heterogeneous XML structure and content. In this paper, information retrieval and database-related techniques have been jointly applied to effectively tolerate XML data diversity in the evaluation of flexible queries. Approximate structure and content matching is supported via a straightforward extension to standard XPath syntax. Also, we outline a query execution technique representing a first step toward efficiently addressing structural pattern queries together with predicate support over XML elements content
Dynamical Casimir effect in a Josephson metamaterial
Vacuum modes confined into an electromagnetic cavity give rise to an
attractive interaction between the opposite walls. When the distance between
the walls is changed non-adiabatically, virtual vacuum modes are turned into
real particles, i.e. photons are generated out of the vacuum. These effects are
known as the static and dynamical Casimir effect, respectively. Here we
demonstrate the dynamical Casimir effect using a Josephson metamaterial
embedded in a microwave cavity at 5.4 GHz. We achieve the non-adiabatic change
in the effective length of the cavity by flux-modulation of the SQUID-based
metamaterial, which results in a few percent variation in the velocity of
light. We show that energy-correlated photons are generated from the ground
state of the cavity and that their power spectra display a bimodal frequency
distribution. These results are in excellent agreement with theoretical
predictions, all the way to the regime where classical parametric effects
cannot be of consequence.Comment: 4 pages, 3 figures, supplement at http://ltl.tkk.fi/~pjh/DCE
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