490 research outputs found
Temporalized logics and automata for time granularity
Suitable extensions of the monadic second-order theory of k successors have
been proposed in the literature to capture the notion of time granularity. In
this paper, we provide the monadic second-order theories of downward unbounded
layered structures, which are infinitely refinable structures consisting of a
coarsest domain and an infinite number of finer and finer domains, and of
upward unbounded layered structures, which consist of a finest domain and an
infinite number of coarser and coarser domains, with expressively complete and
elementarily decidable temporal logic counterparts.
We obtain such a result in two steps. First, we define a new class of
combined automata, called temporalized automata, which can be proved to be the
automata-theoretic counterpart of temporalized logics, and show that relevant
properties, such as closure under Boolean operations, decidability, and
expressive equivalence with respect to temporal logics, transfer from component
automata to temporalized ones. Then, we exploit the correspondence between
temporalized logics and automata to reduce the task of finding the temporal
logic counterparts of the given theories of time granularity to the easier one
of finding temporalized automata counterparts of them.Comment: Journal: Theory and Practice of Logic Programming Journal Acronym:
TPLP Category: Paper for Special Issue (Verification and Computational Logic)
Submitted: 18 March 2002, revised: 14 Januari 2003, accepted: 5 September
200
Quantifying the long-term influence of scientific publications
We consider the long-term indirect influence of publications on subsequent publications. In particular, we are here interested in long-term scientific influence at the level of disciplines. We present a novel method to quantify the long-term scientific influence of publications, considering both direct and indirect, or higher-order citations. We apply this method to Web of Science data at the level of disciplines. Preliminary results for a specific operationalization of the notion of long-term scientific influence suggest that long-term influence is dominated by a few disciplines: Astronomy and Astrophysics, Basic Life Sciences, and Physics and Material Science.</p
Quantifying the long-term influence of scientific publications
We consider the long-term indirect influence of publications on subsequent publications. In particular, we are here interested in long-term scientific influence at the level of disciplines. We present a novel method to quantify the long-term scientific influence of publications, considering both direct and indirect, or higher-order citations. We apply this method to Web of Science data at the level of disciplines. Preliminary results for a specific operationalization of the notion of long-term scientific influence suggest that long-term influence is dominated by a few disciplines: Astronomy and Astrophysics, Basic Life Sciences, and Physics and Material Science.</p
Relationship among research collaboration, number of documents and number of citations. A case study in Spanish computer science production in 2000-2009.
This paper analyzes the relationship among research collaboration, number of documents and number of citations of computer science research activity. It analyzes the number of documents and citations and how they vary by number of authors. They are also analyzed (according to author set cardinality) under different circumstances, that is, when documents are written in different types of collaboration, when documents are published in different document types, when documents are published in different computer science subdisciplines, and, finally, when documents are published by journals with different impact factor quartiles. To investigate the above relationships, this paper analyzes the publications listed in the Web of Science and produced by active Spanish university professors between 2000 and 2009, working in the computer science field. Analyzing all documents, we show that the highest percentage of documents are published by three authors, whereas single-authored documents account for the lowest percentage. By number of citations, there is no positive association between the author cardinality and citation impact. Statistical tests show that documents written by two authors receive more citations per document and year than documents published by more authors. In contrast, results do not show statistically significant differences between documents published by two authors and one author. The research findings suggest that international collaboration results on average in publications with higher citation rates than national and institutional collaborations. We also find differences regarding citation rates between journals and conferences, across different computer science subdisciplines and journal quartiles as expected. Finally, our impression is that the collaborative level (number of authors per document) will increase in the coming years, and documents published by three or four authors will be the trend in computer science literature
On the Hybrid Extension of CTL and CTL+
The paper studies the expressivity, relative succinctness and complexity of
satisfiability for hybrid extensions of the branching-time logics CTL and CTL+
by variables. Previous complexity results show that only fragments with one
variable do have elementary complexity. It is shown that H1CTL+ and H1CTL, the
hybrid extensions with one variable of CTL+ and CTL, respectively, are
expressively equivalent but H1CTL+ is exponentially more succinct than H1CTL.
On the other hand, HCTL+, the hybrid extension of CTL with arbitrarily many
variables does not capture CTL*, as it even cannot express the simple CTL*
property EGFp. The satisfiability problem for H1CTL+ is complete for triply
exponential time, this remains true for quite weak fragments and quite strong
extensions of the logic
Planck-LFI radiometers' spectral response
The Low Frequency Instrument (LFI) is an array of pseudo-correlation
radiometers on board the Planck satellite, the ESA mission dedicated to
precision measurements of the Cosmic Microwave Background. The LFI covers three
bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central
frequency.
The characterization of the broadband frequency response of each radiometer
is necessary to understand and correct for systematic effects, particularly
those related to foreground residuals and polarization measurements. In this
paper we present the measured band shape of all the LFI channels and discuss
the methods adopted for their estimation. The spectral characterization of each
radiometer was obtained by combining the measured spectral response of
individual units through a dedicated RF model of the LFI receiver scheme.
As a consistency check, we also attempted end-to-end spectral measurements of
the integrated radiometer chain in a cryogenic chamber. However, due to
systematic effects in the measurement setup, only qualitative results were
obtained from these tests. The measured LFI bandpasses exhibit a moderate level
of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
Advanced modelling of the Planck-LFI radiometers
The Low Frequency Instrument (LFI) is a radiometer array covering the 30-70
GHz spectral range on-board the ESA Planck satellite, launched on May 14th,
2009 to observe the cosmic microwave background (CMB) with unprecedented
precision. In this paper we describe the development and validation of a
software model of the LFI pseudo-correlation receivers which enables to
reproduce and predict all the main system parameters of interest as measured at
each of the 44 LFI detectors. These include system total gain, noise
temperature, band-pass response, non-linear response. The LFI Advanced RF Model
(LARFM) has been constructed by using commercial software tools and data of
each radiometer component as measured at single unit level. The LARFM has been
successfully used to reproduce the LFI behavior observed during the LFI
ground-test campaign. The model is an essential element in the database of LFI
data processing center and will be available for any detailed study of
radiometer behaviour during the survey.Comment: 21 pages, 15 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
Drop-out rate from the liver transplant waiting list due to HCC progression in HCV-infected patients treated with direct acting antivirals.
BACKGROUND & AIM: concerns about an increased hepatocellular carcinoma (HCC) recurrence rate following directly acting antiviral (DAA) therapy in cirrhotic patients with a prior complete oncological response have been raised. Data regarding the impact of HCV-treatment with DAAs on waiting list drop-out rates in patients with active HCC and HCV-related cirrhosis awaiting liver transplantation (LT) are lacking.
MATERIALS AND METHODS: HCV-HCC patients listed for LT between January 2015 and May 2016 at Padua Liver Transplant Centre were considered eligible for the study. After enrollment patients were divided into 2 groups, depending on whether they underwent DAAs treatment while awaiting LT or not. For each patient clinical, serological and virological data were collected. HCC characteristics were radiologically evaluated at baseline and during follow-up (FU). For transplanted patients, pathological assessment of the explants was performed and recurrence-rates were calculated.
RESULTS: twenty-three patients treated with DAAs and 23 controls were enrolled. HCC characteristics at time of LT-listing were comparable between the 2 groups. Median FU was 10 and 7 months, respectively, during which 2/23 (8.7%) and 1/23 (4.3%) drop-out events due to HCC-progression were registered (p = 0.9). No significant differences in terms of radiological progression were highlighted (p = 0.16). Nine out of 23 cases (39%) and 14/23 (61%) controls underwent LT, and histopathological analysis showed no differences in terms of median number and total tumor volume of HCC nodules, tumor differentiation or microvascular invasion. During post-LT FU, 1/8 DAAs treated patient (12,5%) and 1/12 control (8,3%) experienced HCC recurrence (p = 0.6).
CONCLUSIONS: Viral eradication does not seem to be associated with an increased risk of drop-out due to neoplastic progression in HCV-HCC patients awaiting LT
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