2,888 research outputs found
A Monthly Indicator of the French Business Climate
In France, the business tendency surveys conducted in all the important sectors of the economy are key components in diagnosing the economic outlook. Over the years, INSEE has gradually introduced business climate indicators for each business sector. Such indicators summarise the data contained in the many balances of opinion supplied by the surveys and enable to measure the economic situation each month. An indicator of this kind has been lacking, however, for the economy as the whole. To fill this gap and enrich the existing panel of business climate indicators we provide in this paper the first composite indicator based on French business surveys covering all the important economic sectors of the French economy. We chose the dynamic factor analysis to deal with mixed and changing frequencies and time availability of the data. Parameters are estimated by maximum likelihood based on the Kalman filter. Several indicators can be estimated according to the type (sector-based business climate indicators or elementary components) and the number of variables included in the model. To validate our results and choose the best indicator, we defined three criteria : real-time stability, predictive accuracy to forecast GDP growth and ability to reproduce French business cycles. The new monthly synthetic indicator which passed the tests best allows a clear and simple interpretation of all the business surveys and can deliver each month an early and accurate quantitative message concerning the current business climate in France. This indicator can also be used to improve GDP growth forecast.business survey, dynamic factor analysis, unobserved components model, Kalman filter
State space c-reductions for concurrent systems in rewriting logic
We present c-reductions, a state space reduction technique.
The rough idea is to exploit some equivalence relation on states (possibly capturing system regularities) that preserves behavioral properties, and explore the induced quotient system. This is done by means of a canonizer
function, which maps each state into a (non necessarily unique) canonical representative of its equivalence class. The approach exploits the expressiveness of rewriting logic and its realization in Maude to enjoy several advantages over similar approaches: exibility and simplicity in
the definition of the reductions (supporting not only traditional symmetry reductions, but also name reuse and name abstraction); reasoning support for checking and proving correctness of the reductions; and automatization
of the reduction infrastructure via Maude's meta-programming
features. The approach has been validated over a set of representative case studies, exhibiting comparable results with respect to other tools
A decision support system for elective surgery scheduling under uncertain durations
The operation room (OR) is one of the most expensive material resources in hospitals. Additionally, the demand for surgical service is increasing due to the aging population, while the number of surgical interventions performed is stagnated because of budget reasons. In this context, the importance of improving the efficiency of the surgical service is accentuated. The main objective of this work is to propose and to evaluate a Decision Support System (DSS) for helping medical staff in the automatic scheduling of elective patients, improving the efficiency of medical teams'' work. First, the scheduling criteria are fixed and then the scheduling problem of elective patients is approached by a mathematical programming model. A heuristic algorithm is proposed and included in the DSS. Moreover, other different features are implemented in a software tool with a friendly user interface, called CIPLAN. Considering realistic data, a simulation comparison of the scheduling obtained using the approach presented in this paper and other similar approaches in the bibliography is shown and analyzed. On the other hand, a case study considering real data provided by the Orthopedic Surgical Department (OSD) of the "Lozano Blesa" hospital in Zaragoza (HCU) is proposed. The simulation results show that the approach presented here obtains similar occupation rates and similar confidence levels of not exceeding the available time than approaches in the bibliography. However, from the point of view of respecting the order of the patients in the waiting list, the approach in this paper obtains scheduling much more ordered. In the case of the Orthopedic Surgical Department of the "Lozano Blesa" hospital in Zaragoza, the occupation rate may be increased by 2.83%, which represents a saving of 110, 000 euros per year. Moreover, medical doctors (who use this tool) consider CIPLAN as an intuitive, rapid and efficient software solution that can make easier the corresponding task
Towards Generic Monitors for Object-Oriented Real-Time Maude Specifications
Non-Functional Properties (NFPs) are crucial in the design of software. Specification of systems is used in the very first phases of the software development process for the stakeholders to make decisions on which architecture or platform to use. These specifications may be an- alyzed using different formalisms and techniques, simulation being one of them. During a simulation, the relevant data involved in the anal- ysis of the NFPs of interest can be measured using monitors. In this work, we show how monitors can be parametrically specified so that the instrumentation of specifications to be monitored can be automatically performed. We prove that the original specification and the automati- cally obtained specification with monitors are bisimilar by construction. This means that the changes made on the original system by adding monitors do not affect its behavior. This approach allows us to have a library of possible monitors that can be safely added to analyze different properties, possibly on different objects of our systems, at will.Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech. Spanish MINECO/FEDER project TIN2014-52034-R, NSF Grant CNS 13-19109
Red Quasars and Quasar Evolution: the Case of BALQSO FIRST J155633.8+351758
We present the first near-IR spectroscopy of the z=1.5 radio-loud BALQSO
FIRST J155633.8+351758. Both the Balmer decrement and the slope of the
rest-frame UV-optical continuum independently suggest a modest amount of
extinction along the line of sight to the BLR (E(B-V)~0.5 for SMC-type screen
extinction at the QSO redshift). The implied gas column density along the line
of sight is much less than is implied by the weak X-ray flux of the object,
suggesting that either the BLR and BAL region have a low dust-to-gas ratio, or
that the rest-frame optical light encounters significantly lower mean column
density lines of sight than the X-ray emission. From the rest-frame UV-optical
spectrum, we are able to constrain the stellar mass content of the system.
Comparing the maximal stellar mass with the black hole mass estimated from the
bolometric luminosity of the QSO, we find that the ratio of the black hole to
stellar mass may be comparable to the Magorrian value, which would imply that
the Magorrian relation is already in place at z=1.5. However, multiple factors
favor a much larger black hole to stellar mass ratio. This would imply that if
the Magorrian relation characterizes the late history of QSOs, and the
situation observed for F1556+3517 is typical of the early evolutionary history
of QSOs, central black hole masses develop more rapidly than bulge masses.
[ABRIDGED]Comment: 23 pages, 4 embedded postscript figures; Accepted for publication in
The Astronomical Journal, December 200
Generic Encodings of Constructor Rewriting Systems
Rewriting is a formalism widely used in computer science and mathematical
logic. The classical formalism has been extended, in the context of functional
languages, with an order over the rules and, in the context of rewrite based
languages, with the negation over patterns. We propose in this paper a concise
and clear algorithm computing the difference over patterns which can be used to
define generic encodings of constructor term rewriting systems with negation
and order into classical term rewriting systems. As a direct consequence,
established methods used for term rewriting systems can be applied to analyze
properties of the extended systems. The approach can also be seen as a generic
compiler which targets any language providing basic pattern matching
primitives. The formalism provides also a new method for deciding if a set of
patterns subsumes a given pattern and thus, for checking the presence of
useless patterns or the completeness of a set of patterns.Comment: Added appendix with proofs and extended example
The Nuclear Reddening Curve for Active Galactic Nuclei and the Shape of the Infra-Red to X-Ray Spectral Energy Distribution
We present extinction curves derived from the broad emission lines and
continua of large samples of both radio-loud and radio-quiet AGNs. The curves
are significantly flatter in the UV than are curves for the local ISM. The
reddening curves for the radio-quiet LBQS quasars are slightly steeper than
those of the radio-loud quasars in the UV, probably because of additional
reddening by dust further out in the host galaxies of the former. The UV
extinction curves for the radio-loud AGNs are very flat. This is explicable
with slight modifications to standard MRN dust models: there is a relative lack
of small grains in the nuclear dust. Our continuum and broad-emission line
reddening curves agree in both shape and amplitude, confirming that the
continuum shape is indeed profoundly affected by reddening for all but the
bluest AGNs. With correction by our generic extinction curve, all of the
radio-loud AGNs have continuous optical-UV spectra consistent with a single
shape. We show that radio-quiet AGNs have very similar intrinsic UV to optical
shape over orders of magnitude in luminosity. We also argue that radio-loud and
radio-quiet AGNs probably share the same underlying continuum shape and that
most of the systematic differences between their observed continuum shapes are
due to higher nuclear reddening in radio-selected AGNs, and additional
reddening from dust further out in the host galaxies in radio-quiet AGNs. Our
conclusions have important implications for the modelling of quasar continua
and the analysis of quasar demographics.Comment: 41 pages, including 6 figures and 3 tables. To appear in ApJ vol.
614, October 20 issue. Some slight wording changes. Some additional
references added. Small changes in the model fit in section 6.2, to the
analytical fit in the Appendix, and to the tabulated reddening curve in the
Appendi
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