4,326 research outputs found
Measuring the complex orbital angular momentum spectrum and spatial mode decomposition of structured light beams
Light beams carrying orbital angular momentum are key resources in modern
photonics. In many applications, the ability of measuring the complex spectrum
of structured light beams in terms of these fundamental modes is crucial. Here
we propose and experimentally validate a simple method that achieves this goal
by digital analysis of the interference pattern formed by the light beam and a
reference field. Our approach allows one to characterize the beam radial
distribution also, hence retrieving the entire information contained in the
optical field. Setup simplicity and reduced number of measurements could make
this approach practical and convenient for the characterization of structured
light fields.Comment: 8 pages (including Methods and References), 6 figure
Photon energy lifter
We propose a time-dependent photonic structure, in which the carrier
frequency of an optical pulse is shifted without changing its shape. The
efficiency of the device takes advantage of slow group velocities of light
attainable in periodic photonic structures. The frequency shifting effect is
quantitatively studied by means of Finite Difference Time Domain simulations
for realistic systems with optical parameters of conventional silicon
technology.Comment: 4 pages 5 figure
Stellar 3-D kinematics in the Draco dwarf spheroidal galaxy
Aims. We present the first three-dimensional internal motions for individual
stars in the Draco dwarf spheroidal galaxy. Methods. By combining first-epoch
observations and second-epoch Data Release
2 positions, we measured the proper motions of sources in the direction
of Draco. We determined the line-of-sight velocities for a sub-sample of
red giant branch stars using medium resolution spectra acquired with the DEIMOS
spectrograph at the Keck II telescope. Altogether, this resulted in a final
sample of Draco members with high-precision and accurate 3D motions, which
we present as a table in this paper. Results. Based on this high-quality
dataset, we determined the velocity dispersions at a projected distance of
pc from the centre of Draco to be
km/s, km/s and
km/s in the projected radial, tangential, and line-of-sight directions. This
results in a velocity anisotropy at
pc. Tighter constraints may be obtained using the spherical Jeans equations and
assuming constant anisotropy and Navarro-Frenk-White (NFW) mass profiles, also
based on the assumption that the 3D velocity dispersion should be lower than
of the escape velocity of the system. In this case, we constrain
the maximum circular velocity of Draco to be in the range of
km/s. The corresponding mass range is in good agreement with
previous estimates based on line-of-sight velocities only. Conclusions. Our
Jeans modelling supports the case for a cuspy dark matter profile in this
galaxy. Firmer conclusions may be drawn by applying more sophisticated models
to this dataset and with new datasets from upcoming releases.Comment: 12 pages, 15 figures, 3 tables. Accepted for publication by A&
Quantum-inspired Machine Learning on high-energy physics data
Tensor Networks, a numerical tool originally designed for simulating quantum
many-body systems, have recently been applied to solve Machine Learning
problems. Exploiting a tree tensor network, we apply a quantum-inspired machine
learning technique to a very important and challenging big data problem in high
energy physics: the analysis and classification of data produced by the Large
Hadron Collider at CERN. In particular, we present how to effectively classify
so-called b-jets, jets originating from b-quarks from proton-proton collisions
in the LHCb experiment, and how to interpret the classification results. We
exploit the Tensor Network approach to select important features and adapt the
network geometry based on information acquired in the learning process.
Finally, we show how to adapt the tree tensor network to achieve optimal
precision or fast response in time without the need of repeating the learning
process. These results pave the way to the implementation of high-frequency
real-time applications, a key ingredient needed among others for current and
future LHCb event classification able to trigger events at the tens of MHz
scale.Comment: 13 pages, 4 figure
Variable Definition and Independent Components
In the causal modelling literature, it is well known that âill-definedâ variables may give rise to âambiguous manipulationsâ (Spirtes and Scheines, 2004). Here, we illustrate how ill-defined variables may also induce mistakes in causal inference when standard causal search methods are applied (Spirtes et al., 2000; Pearl, 2009). To address the problem, we introduce a representation framework, which exploits an independent component representation of the data, and demonstrate its potential for detecting ill-defined variables and avoiding mistaken causal inferences
Sentiment Analysis for Performance Evaluation of Maintenance in Healthcare
This paper presents a framework which makes use of Sentiment Analysis techniques for retrieving Real World Data (RWD) starting from scheduled and corrective maintenance data. The scope of the analysis is to automatically extract features from maintenance work orders, in order to calculate Key Performance Indicators of maintenance operations on medical devices, for Health Technologies Assessment purposes. Data are extracted from Computerized Maintenance Management System reports of healthcare facilities
Erase and Rewind: Manual Correction of NLP Output through a Web Interface
In this paper, we present Tintful, an NLP annotation software that can be used both to manually annotate texts and to fix mistakes in NLP pipelines, such as Stanford CoreNLP. Using a paradigm similar to wiki-like systems, a user who notices some wrong annotation can easily fix it and submit the resulting (and right) entry back to the tool developers. Moreover, Tintful can be used to easily annotate data from scratch. The input documents do not need to be in a particular format: starting from the plain text, the sentences are first annotated with CoreNLP, then the user can edit the annotations and submit everything back through a user-friendly interface
- âŠ