145 research outputs found
Master crossover functions for the one-component fluid "subclass"
Introducing three well-defined dimensionless numbers, we establish the link
between the scale dilatation method able to estimate master (i.e. unique)
singular behaviors of the one-component fluid "subclass" and the universal
crossover functions recently estimated [Garrabos and Bervillier, Phys. Rev. E
74, 021113 (2006)] from the bounded results of the massive renormalization
scheme applied to the..
Master crossover behavior of parachor correlations for one-component fluids
The master asymptotic behavior of the usual parachor correlations, expressing
surface tension as a power law of the density difference
between coexisting liquid and vapor, is analyzed for a
series of pure compounds close to their liquid-vapor critical point, using only
four critical parameters , , and ,
for each fluid.
... The main consequences of these theoretical estimations are discussed in
the light of engineering applications and process simulations where parachor
correlations constitute one of the most practical method for estimating surface
tension from density and capillary rise measurements
Effect of maternal obesity and preconceptional weight loss on male and female offspring metabolism and olfactory performance in mice
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. According to the “developmental origins of health and disease” (DOHaD) concept, maternal obesity predisposes the offspring to non-communicable diseases in adulthood. While a preconceptional weight loss (WL) is recommended for obese women, its benefits on the offspring have been poorly addressed. We evaluated whether preconceptional WL was able to reverse the adverse effects of maternal obesity in a mouse model, exhibiting a modification of foetal growth and of the expression of genes encoding epigenetic modifiers in liver and placenta. We tracked metabolic and olfactory behavioural trajectories of offspring born to control, obese or WL mothers. After weaning, the offspring were either put on a control diet (CD) or a high-fat (HFD). After only few weeks of HFD, the offspring developed obesity, metabolic alterations and olfactory impairments, independently of maternal context. However, male offspring born to obese mother gained even more weight under HFD than their counterparts born to lean mothers. Preconceptional WL normalized the offspring metabolic phenotypes but had unexpected effects on olfactory performance: a reduction in olfactory sensitivity, along with a lack of fasting-induced, olfactory-based motivation. Our results confirm the benefits of maternal preconceptional WL for male offspring metabolic health but highlight some possible adverse outcomes on olfactory-based behaviours
Are Surgical Trials with Negative Results Being Interpreted Correctly?
BACKGROUND: Many published accounts of clinical trials report no differences between the treatment arms,
while being underpowered to find differences. This study determined how the authors of
these reports interpreted their findings.
STUDY DESIGN: We examined 54 reports of surgical trials chosen randomly from a database of 110 influential
trials conducted in 2008. Seven that reported having adequate statistical power (b 0.9)
were excluded from further analysis, as were the 32 that reported significant differences
between the treatment arms. We examined the remaining 15 to see whether the authors interpreted
their negative findings appropriately. Appropriate interpretations discussed the lack of
power and/or called for larger studies.
RESULTS: Three of the 7 trials that did not report an a priori power calculation offered inappropriate
interpretations, as did 3 of the 8 trials that reported an a priori power < 0.90. However, we
examined only a modest number of trial reports from 1 year.
CONCLUSIONS: Negative findings in underpowered trials were often interpreted as showing the equivalence of
the treatment arms with no discussion of the issue of being underpowered. This may lead
clinicians to accept new treatments that have not been validated
Master singular behavior for the Sugden factor of the one-component fluids near their gas-liquid critical point
We present the master (i.e. unique) behavior of the squared capillary length
- so called the Sudgen factor-, as a function of the temperature-like field
along the critical isochore, asymptotically close to the gas-liquid critical
point of twenty (one component) fluids. This master behavior is obtained using
the scale dilatation of the relevant physical fields of the one-component
fluids. The scale dilatation introduces the fluid-dependent scale factors in a
manner analog with the linear relations between physical fields and scaling
fields needed by the renormalization theory applied to the Ising-like
universality class. The master behavior for the Sudgen factor satisfies
hyperscaling and can be asymptotically fitted by the leading terms of the
theoretical crossover functions for the correlation length and the
susceptibility in the homogeneous domain recently obtained from massive
renormalization in field theory. In the absence of corresponding estimation of
the theoretical crossover functions for the interfacial tension, we define the
range of the temperature-like field where the master leading power law can be
practically used to predict the singular behavior of the Sudgen factor in
conformity with the theoretical description provided by the massive
renormalization scheme within the extended asymptotic domain of the
one-component fluid "subclass"
Gaia Focused Product Release: A catalogue of sources around quasars to search for strongly lensed quasars
Context. Strongly lensed quasars are fundamental sources for cosmology. The
Gaia space mission covers the entire sky with the unprecedented resolution of
" in the optical, making it an ideal instrument to search for
gravitational lenses down to the limiting magnitude of 21. Nevertheless, the
previous Gaia Data Releases are known to be incomplete for small angular
separations such as those expected for most lenses. Aims. We present the Data
Processing and Analysis Consortium GravLens pipeline, which was built to
analyse all Gaia detections around quasars and to cluster them into sources,
thus producing a catalogue of secondary sources around each quasar. We analysed
the resulting catalogue to produce scores that indicate source configurations
that are compatible with strongly lensed quasars. Methods. GravLens uses the
DBSCAN unsupervised clustering algorithm to detect sources around quasars. The
resulting catalogue of multiplets is then analysed with several methods to
identify potential gravitational lenses. We developed and applied an outlier
scoring method, a comparison between the average BP and RP spectra of the
components, and we also used an extremely randomised tree algorithm. These
methods produce scores to identify the most probable configurations and to
establish a list of lens candidates. Results. We analysed the environment of 3
760 032 quasars. A total of 4 760 920 sources, including the quasars, were
found within 6" of the quasar positions. This list is given in the Gaia
archive. In 87\% of cases, the quasar remains a single source, and in 501 385
cases neighbouring sources were detected. We propose a list of 381 lensed
candidates, of which we identified 49 as the most promising. Beyond these
candidates, the associate tables in this Focused Product Release allow the
entire community to explore the unique Gaia data for strong lensing studies
further.Comment: 35 pages, 60 figures, accepted for publication by Astronomy and
Astrophysic
El Pensamiento Probabilístico de los Profesores de Biología en Formación
Los futuros profesores de secundaria requieren de una formación acorde a las demandas de la sociedad del siglo XXI. Ello impone el desarrollo de un pensamiento que le permita interpretar y abordar los fenómenos de naturaleza aleatoria. El objetivo de este trabajo es determinar las tendencias de pensamiento probabilístico de los estudiantes de los profesorados de Biología de la provincia de Mendoza, Argentina. Para ello se aplicó un cuestionario a los 325 estudiantes que cursan esta carrera. El mismo consta de tres partes; la primera trata sobre las variables demográficas de los estudiantes, la segunda corresponde al reconocimiento de la aleatoriedad; y la tercera a la estimación de la probabilidad de diferentes sucesos. Las respuestas se analizaron a partir de la aplicación de diferentes técnicas estadísticas; el test de independencia, el análisis de la varianza, el test de Tukey, análisis de clusters y análisis discriminante. En primer lugar, se encontraron diferencias significativas entre el reconocimiento de la aleatoriedad y el contexto del suceso, siendo mayor en el contexto de juego que en el físico natural. Mientras que, en el contexto físico natural se afirma la aleatoriedad desde la causalidad, en el de juego se afirma desde la incertidumbre. En segundo lugar, no se encontró relación de dependencia entre el reconocimiento de la aleatoriedad y la edad de los estudiantes, como así tampoco con el nivel académico de los mismos. Respecto a la estimación de la probabilidad, los estudiantes argumentan fundamentalmente desde la equiprobabilidad y desde la contingencia. El análisis de clusters y análisis discriminante permitieron encontrar cuatro tendencias de pensamiento: incertidumbre, determinista, contingente y personalista
Gaia Focused Product Release: Radial velocity time series of long-period variables
The third Gaia Data Release (DR3) provided photometric time series of more
than 2 million long-period variable (LPV) candidates. Anticipating the
publication of full radial-velocity (RV) in DR4, this Focused Product Release
(FPR) provides RV time series for a selection of LPVs with high-quality
observations. We describe the production and content of the Gaia catalog of LPV
RV time series, and the methods used to compute variability parameters
published in the Gaia FPR. Starting from the DR3 LPVs catalog, we applied
filters to construct a sample of sources with high-quality RV measurements. We
modeled their RV and photometric time series to derive their periods and
amplitudes, and further refined the sample by requiring compatibility between
the RV period and at least one of the , , or
photometric periods. The catalog includes RV time series and variability
parameters for 9\,614 sources in the magnitude range , including a flagged top-quality subsample of 6\,093 stars
whose RV periods are fully compatible with the values derived from the ,
, and photometric time series. The RV time series
contain a mean of 24 measurements per source taken unevenly over a duration of
about three years. We identify the great most sources (88%) as genuine LPVs,
with about half of them showing a pulsation period and the other half
displaying a long secondary period. The remaining 12% consists of candidate
ellipsoidal binaries. Quality checks against RVs available in the literature
show excellent agreement. We provide illustrative examples and cautionary
remarks. The publication of RV time series for almost 10\,000 LPVs constitutes,
by far, the largest such database available to date in the literature. The
availability of simultaneous photometric measurements gives a unique added
value to the Gaia catalog (abridged)Comment: 36 pages, 38 figure
Sequential and parallel solution-biased search for subgraph algorithms
Funding: This work was supported by the Engineering and Physical Sciences Research Council (grant numbers EP/P026842/1, EP/M508056/1, and EP/N007565).The current state of the art in subgraph isomorphism solving involves using degree as a value-ordering heuristic to direct backtracking search. Such a search makes a heavy commitment to the first branching choice, which is often incorrect. To mitigate this, we introduce and evaluate a new approach, which we call “solution-biased search”. By combining a slightly-random value-ordering heuristic, rapid restarts, and nogood recording, we design an algorithm which instead uses degree to direct the proportion of search effort spent in different subproblems. This increases performance by two orders of magnitude on satisfiable instances, whilst not affecting performance on unsatisfiable instances. This algorithm can also be parallelised in a very simple but effective way: across both satisfiable and unsatisfiable instances, we get a further speedup of over thirty from thirty-six cores, and over one hundred from ten distributed-memory hosts. Finally, we show that solution-biased search is also suitable for optimisation problems, by using it to improve two maximum common induced subgraph algorithms.Postprin
Improving a branch-and-bound approach for the degree-constrained minimum spanning tree problem with LKH
The degree-constrained minimum spanning tree problem, which involves finding a minimum spanning tree of a given graph with upper bounds on the vertex degrees, has found multiple applications in several domains. In this paper, we propose a novel CP approach to tackle this problem where we extend a recent branch-and-bound approach with an adaptation of the LKH local search heuristic to deal with trees instead of tours. Every time a solution is found, it is locally optimised by our new heuristic, thus yielding a tightened cut. Our experimental evaluation shows that this significantly speeds up the branch-and-bound search and hence closes the performance gap to the state-of-the-art bottom-up CP approach
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