3,307 research outputs found
A feasible algorithm for typing in Elementary Affine Logic
We give a new type inference algorithm for typing lambda-terms in Elementary
Affine Logic (EAL), which is motivated by applications to complexity and
optimal reduction. Following previous references on this topic, the variant of
EAL type system we consider (denoted EAL*) is a variant without sharing and
without polymorphism. Our algorithm improves over the ones already known in
that it offers a better complexity bound: if a simple type derivation for the
term t is given our algorithm performs EAL* type inference in polynomial time.Comment: 20 page
On a new theoretical framework for RR Lyrae stars I: the metallicity dependence
We present new nonlinear, time-dependent convective hydrodynamical models of
RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio
and a broad range in metal abundances (Z=0.0001--0.02). The stellar masses and
luminosities adopted to construct the pulsation models were fixed according to
detailed central He burning Horizontal Branch evolutionary models. The
pulsation models cover a broad range in stellar luminosity and effective
temperatures and the modal stability is investigated for both fundamental and
first overtones. We predict the topology of the instability strip as a function
of the metal content and new analytical relations for the edges of the
instability strip in the observational plane. Moreover, a new analytical
relation to constrain the pulsation mass of double pulsators as a function of
the period ratio and the metal content is provided. We derive new
Period-Radius-Metallicity relations for fundamental and first-overtone
pulsators. They agree quite well with similar empirical and theoretical
relations in the literature. From the predicted bolometric light curves,
transformed into optical (UBVRI) and near-infrared (JHK) bands, we compute the
intensity-averaged mean magnitudes along the entire pulsation cycle and, in
turn, new and homogenous metal-dependent (RIJHK) Period-Luminosity relations.
Moreover, we compute new dual and triple band optical, optical--NIR and NIR
Period-Wesenheit-Metallicity relations. Interestingly, we find that the optical
Period-W(V,B-V) is independent of the metal content and that the accuracy of
individual distances is a balance between the adopted diagnostics and the
precision of photometric and spectroscopic datasets.Comment: 51 pages, 20 figures, 9 tables, accepted for publication on Ap
Fast and Accurate Computation of Orbital Collision Probability for Short-Term Encounters
International audienceThis article provides a new method for computing the probability of collision between two spherical space objects involved in a short-term encounter under Gaussian-distributed uncertainty. In this model of conjunction, classical assumptions reduce the probability of collision to the integral of a two-dimensional Gaussian probability density function over a disk. The computational method presented here is based on an analytic expression for the integral, derived by use of Laplace transform and D-finite functions properties. The formula has the form of a product between an exponential term and a convergent power series with positive coefficients. Analytic bounds on the truncation error are also derived and are used to obtain a very accurate algorithm. Another contribution is the derivation of analytic bounds on the probability of collision itself, allowing for a very fast and - in most cases - very precise evaluation of the risk. The only other analytical method of the literature - based on an approximation - is shown to be a special case of the new formula. A numerical study illustrates the efficiency of the proposed algorithms on a broad variety of examples and favorably compares the approach to the other methods of the literature
Data of postoperative complications related to fibrinogen-to-albumin ratio in pancreatic resections
Pancreatic surgery is one of the surgeries burdened with the highest mortality and morbidity rate. This is due both to the aggressive biological nature of the pathology affecting the organ and to the technical difficulties associated with surgery. A further aspect on which research is focusing is represented by inflammation related to oncological pathology. Inflammation plays an important role in tumor progression, and growing evidence has confirmed that the fibrinogen-to-albumin ratio (FAR) is an important prognostic factor for overall survival (OS) in malignant tumors. Inflammatory markers had demonstrated also a role in the prediction of postoperative complication after pancreatic surgery. We speculate that FAR, as an easily available, cost-effective, and non-invasive prognostic indicator for pancreatic cancer patients, could help to identify patients at increased risk of postoperative pancreatic fistula (POPF). We therefore retrospectively analyzed the data relating to 117 pancreatic resections relating direct and indirect markers of inflammation with the incidence of post-operative complications. (c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/
Postoperative procalcitonin is a biomarker for excluding the onset of clinically relevant pancreatic fistula after pancreaticoduodenectomy
Background: Early detection and therapy of pancreatic fistula after pancreaticoduodenectomy is crucial to improve outcomes of this surgery. Since it is not clear if procalcitonin (PCT), can predict the onset of clinically relevant pancreatic fistula (CR-POPF), we aimed to investigate this ability.Methods: One-hundred-thirty pancreaticoduodenectomies (PD) were analyzed. Receiver Operating Characteristic curves analysis defined the optimal cut-of fs for PCT and drains amylase levels (DAL). Complications were compared using chi-square for proportions test.Results: DAL >_2,000 U/L in postoperative day (POD) 2 had 71% PPV and 91% NPV for CR-POPF (P<0.001). In POD2, PCT >_0.5 ng/mL showed NPV 91% (P<0.045) and increased DAL PPV for CR-POPF to 81%. In POD3, POD4 and POD5, DAL (cut-offs 780 U/L, 157 U/L and 330 U/L, respectively) showed NPV for CR-POPF >90% (P<0.0001). PCT >_0.5 ng/mL showed NPV for CR-POPF of about 90%. In POD5, combining DAL (cut-off 330 U/L) and PCT (cut-off 0.5 ng/mL), a PPV for CR-POPF of 81% was detected. A progressive increased risk of CR-POPF from POD2 (OR =3.05; P=0.0348) to POD5 (OR =4.589; P=0.0082) was observed. In POD2 and 5, PCT >_0.5 ng/mL, alone and in combination with DAL, may be a reliable marker for identifying patients at highest risk of CR-POPF after PD.Conclusions: This association could be proposed to select high risk patients that could benefit of "intensive" postoperative management
Lactic acid bacteria occurring during manufacture and ripening of Provolone del Monaco cheese: detection by different analytical approaches
Lactic acid bacteria occurring in Provolone del Monaco, an artisanal pasta filata cheese produced in Campania (Italy) from raw cowsâ milk and without starter addition, were investigated by a combination of conventional and molecular approaches. The microbial community was monitored during a cheese-making process giving rise to a premium quality product. Streptococcus thermophilus and Streptococcus macedonicus prevailed during cheese manufacture and survived along nine months of ripening, together with enterococci and lactobacilli of the casei group, especially Lactobacillus rhamnosus. Phenotypic and genetic identification of 308 isolates largely reflected the results obtained by 16S rDNA sequencing analysis by polymerase chain reaction-denaturant gradient gel electrophoresis, with the significant exception of Lactobacillus fermentum and four Lactobacillus delbrueckii subspecies that were not detected by cultural methods. Each different analytical approach employed provided useful information. Their combination proved to be suitable to effectively describe the ecosystem of Provolone del Monaco cheese
Characterisation of wine yeasts isolated at different temperatures using the enrichment technique
Research NoteSaccharomyces cerevisiae strains isolated from fermenting grape must incubated at extreme fermentation temperatures (40 and 5 degrees C) were oenologically characterised. These cultures compared with S. cerevisiae wine strains, show a wider optimum temperature for growth and can ferment vigorously in a wider temperature range (27 to 35 degrees C)
The Cepheids of NGC1866: A Precise Benchmark for the Extragalactic Distance Scale and Stellar Evolution from Modern UBVI Photometry
We present the analysis of multiband time-series data for a sample of 24
Cepheids in the field of the Large Magellanic Cloud cluster NGC1866. Very
accurate BVI VLT photometry is combined with archival UBVI data, covering a
large temporal window, to obtain precise mean magnitudes and periods with
typical errors of 1-2% and of 1 ppm, respectively. These results represent the
first accurate and homogeneous dataset for a substantial sample of Cepheid
variables belonging to a cluster and hence sharing common distance, age and
original chemical composition. Comparisons of the resulting multiband
Period-Luminosity and Wesenheit relations to both empirical and theoretical
results for the Large Magellanic Cloud are presented and discussed to derive
the distance of the cluster and to constrain the mass-luminosity relation of
the Cepheids. The adopted theoretical scenario is also tested by comparison
with independent calibrations of the Cepheid Wesenheit zero point based on
trigonometric parallaxes and Baade-Wesselink techniques. Our analysis suggests
that a mild overshooting and/or a moderate mass loss can affect
intermediate-mass stellar evolution in this cluster and gives a distance
modulus of 18.50 +- 0.01 mag. The obtained V,I color-magnitude diagram is also
analysed and compared with both synthetic models and theoretical isochrones for
a range of ages and metallicities and for different efficiencies of core
overshooting. As a result, we find that the age of NGC1866 is about 140 Myr,
assuming Z = 0.008 and the mild efficiency of overshooting suggested by the
comparison with the pulsation models.Comment: 13 pages, 10 figures, accepted in MNRAS (2016 January 14
- âŠ