381 research outputs found
Unimodularity and invariant volume forms for Hamiltonian dynamics on Poisson-Lie groups
In this paper, we discuss several relations between the existence of
invariant volume forms for Hamiltonian systems on Poisson-Lie groups and the
unimodularity of the Poisson-Lie structure. In particular, we prove that
Hamiltonian vector fields on a Lie group endowed with a unimodular Poisson-Lie
structure preserve a multiple of any left-invariant volume on the group.
Conversely, we also prove that if there exists a Hamiltonian function such that
the identity element of the Lie group is a nondegenerate singularity and the
associated Hamiltonian vector field preserves a volume form, then the
Poisson-Lie structure is necessarily unimodular. Furthermore, we illustrate our
theory with different interesting examples, both on semisimple and unimodular
Poisson-Lie groups.Comment: 17 page
The RoPES project with HARPS and HARPS-N. I. A system of super-Earths orbiting the moderately active K-dwarf HD 176986
We report the discovery of a system of two super-Earths orbiting the
moderately active K-dwarf HD 176986. This work is part of the RoPES RV program
of G- and K-type stars, which combines radial velocities (RVs) from the HARPS
and HARPS-N spectrographs to search for short-period terrestrial planets. HD
176986 b and c are super-Earth planets with masses of 5.74 and 9.18
M, orbital periods of 6.49 and 16.82 days, and distances of 0.063
and 0.119 AU in orbits that are consistent with circular. The host star is a
K2.5 dwarf, and despite its modest level of chromospheric activity (log(R'hk) =
- 4.90 +- 0.04), it shows a complex activity pattern. Along with the discovery
of the planets, we study the magnetic cycle and rotation of the star. HD 176986
proves to be suitable for testing the available RV analysis technique and
further our understanding of stellar activity.Comment: 21 pages, 24 figures, 7 table
Exposure to secondhand smoke in the home and mental health in children: a population-based study
OBJECTIVES: To examine the association between exposure to secondhand smoke (SHS) in the home and mental health among children. METHODS: Cross-sectional study of 2357 children representative of the Spanish population aged 4-12 years in 2011-2012. Duration of SHS exposure in children was reported by parents. Probable mental disorder was defined as a score>90th centile in the parental version of the Strengths and Difficulties Questionnaire (SDQ). Statistical analysis was performed with logistic regression and adjusted for sociodemographic variables, lifestyle, neighbourhood environment and family characteristics, including parental mental health. RESULTS: Among study participants, 6.9% (95% CI 5.7% to 8.0%) were exposed to SHS in the home for <1 h/day and 4.5% (95% CI 3.5% to 5.5%) for ≥1 h/day. Compared to children not habitually exposed to SHS, the multivariate ORs for probable mental disorder were 1.49 (95% CI 0.85 to 2.62) for SHS exposure<1 h/day and 2.73 (95% CI 1.38 to 5.41) for SHS exposure≥1 h/day (p for linear trend=0.002). The corresponding ORs for attention-deficit and hyperactivity disorder (ADHD) were 2.18 (95% CI 1.30 to 3.64) for <1 h/day exposure and 3.14 (95% CI 1.63 to 6.04) for ≥1 h/day exposure (p for linear trend<0.001). No association was found between SHS and the rest of the components of the SDQ. CONCLUSIONS: Among children, SHS exposure in the home during ≥1 h/day is associated with a higher frequency of mental disorder. This association was mostly due to the impact of SHS on ADHD
The HADES RV Programme with HARPS-N at TNG XI. GJ 685 b: a warm super-Earth around an active M dwarf
Small rocky planets seem to be very abundant around low-mass M-type stars.
Their actual planetary population is however not yet precisely understood.
Currently several surveys aim to expand the statistics with intensive detection
campaigns, both photometric and spectroscopic. We analyse 106 spectroscopic
HARPS-N observations of the active M0-type star GJ 685 taken over the past five
years. We combine these data with photometric measurements from different
observatories to accurately model the stellar rotation and disentangle its
signals from genuine Doppler planetary signals in the RV data. We run an MCMC
analysis on the RV and activity indexes time series to model the planetary and
stellar signals present in the data, applying Gaussian Process regression
technique to deal with the stellar activity signals. We identify three periodic
signals in the RV time series, with periods of 9, 24, and 18 d. Combining the
analyses of the photometry of the star with the activity indexes derived from
the HARPS-N spectra, we identify the 18 d and 9 d signals as activity-related,
corresponding to the stellar rotation period and its first harmonic
respectively. The 24 d signals shows no relations with any activity proxy, so
we identify it as a genuine planetary signal. We find the best-fit model
describing the Doppler signal of the newly-found planet, GJ 685\,b,
corresponding to an orbital period d and a
minimum mass M. We also study a
sample of 70 RV-detected M-dwarf planets, and present new statistical evidence
of a difference in mass distribution between the populations of single- and
multi-planet systems, which can shed new light on the formation mechanisms of
low-mass planets around late-type stars.Comment: 18 pages, 13 figures, accepted for publication in A&
HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals
Short- to mid-term magnetic phenomena on the stellar surface of M-type stars
cannot only resemble the effects of planets in radial velocity data, but also
may hide them. We analyze 145 spectroscopic HARPS-N observations of GJ 3942
taken over the past five years and additional photometry to disentangle stellar
activity effects from genuine Doppler signals as a result of the orbital motion
of the star around the common barycenter with its planet. To achieve this, we
use the common methods of pre-whitening, and treat the correlated red noise by
a first-order moving average term and by Gaussian-process regression following
an MCMC analysis. We identify the rotational period of the star at 16.3 days
and discover a new super-Earth, GJ 3942 b, with an orbital period of 6.9 days
and a minimum mass of 7.1 Me. An additional signal in the periodogram of the
residuals is present but we cannot claim it to be related to a second planet
with sufficient significance at this point. If confirmed, such planet candidate
would have a minimum mass of 6.3 Me and a period of 10.4 days, which might
indicate a 3:2 mean-motion resonance with the inner planet
HADES RV Programme with HARPS-N at TNG. VII. Rotation and activity of M-Dwarfs from time-series high-resolution spectroscopy of chromospheric indicators
We aim to investigate the presence of signatures of magnetic cycles and
rotation on a sample of 71 early M-dwarfs from the HADES RV programme using
high-resolution time-series spectroscopy of the Ca II H & K and Halpha
chromospheric activity indicators, the radial velocity series, the parameters
of the cross correlation function and the V-band photometry. We used mainly
HARPS-N spectra, acquired over four years, and add HARPS spectra from the
public ESO database and ASAS photometry light-curves as support data, extending
the baseline of the observations of some stars up to 12 years. We provide
log(R'hk) measurements for all the stars in the sample, cycle length
measurements for 13 stars, rotation periods for 33 stars and we are able to
measure the semi-amplitude of the radial velocity signal induced by rotation in
16 stars. We complement our work with previous results and confirm and refine
the previously reported relationships between the mean level of chromospheric
emission, measured by the log(R'hk), with the rotation period, and with the
measured semi-amplitude of the activity induced radial velocity signal for
early M-dwarfs. We searched for a possible relation between the measured
rotation periods and the lengths of the magnetic cycle, finding a weak
correlation between both quantities. Using previous v sin i measurements we
estimated the inclinations of the star's poles to the line of sight for all the
stars in the sample, and estimate the range of masses of the planets GJ 3998 b
and c (2.5 - 4.9 Mearth and 6.3 - 12.5 Mearth), GJ 625 b (2.82 Mearth), GJ 3942
b (7.1 - 10.0 Mearth) and GJ 15A b (3.1 - 3.3 Mearth), assuming their orbits
are coplanar with the stellar rotation.Comment: 19 pages, 16 figures, 10 table
Sustainable wastewater treatment plants design through multiobjective optimization
Nowadays, an adequate design of wastewater treatment plants taking into consideration ail sustainability dimensions- economic, environmental and social- is fundamental. This can be achieved by implementing systematic methodologies where conceptual and mathematical tools can be used together. This contribution proposes a framework that uses total cost, consumed energy, and reclaimed wastewater as sustainability metrics. A mixed-integer nonlinear programming problem arises from a general superstructure for wastewater treatment plants. A case study from Mexico City is solved by a hybrid multiobjective optimization approach that combines lexicographie and e-constraint methods. Solutions are provided in the form of a Pareto front. A modified technique for order of preference by similarity to ideal solution (MTOPSIS) analysis is used as a multiple criteria decision-making tool to find the best trade-off solution. The optimal sustainable configuration resulted consists of three levels of treatment and 100% of treated water reuse
Factores que inciden en el citodiagnóstico no útil. Policlínico "5 de Septiembre". Consolación del Sur. Enero-diciembre 2002. Factors bearing on useless cyto-diagnosis. “5 de septiembre” Outpatient Clinic. Consolacion del Sur. January-December 2002
Se realizó un estudio descriptivo retrospectivo con el objetivo de identificar los factores que inciden en la citología no útil para el diagnóstico perteneciente al área de Policlínico Docente "5 de Septiembre" del municipio Consolación del Sur en el periodo comprendido entre enero y diciembre del 2001, donde se tomó muestra de citología a 1754 pacientes de los cuales resultaron no útil para el diagnóstico 105 y el total de negativas fue de 1649 lo que proporciona un índice de no útil de 6.3 %, por encima de la media provincial en el estudio se comprobó que el 65.7 de citología no útil fue debido a la aparición de Sepsis vaginal y en el 34.2 % la causa estuvo dada por mala toma de la muestra, siendo estos dos factores lo más relevantes que inciden en la citología no útil. Además se pudo apreciar mediante una comprobación de conocimientos que el personal de enfermería tiene dificultades para aplicar en la practica en programa de detección precoz del cáncer cérvico uterino. DeCS: CITODIAGNOSTICO, SEPSIS VAGINAL, ATENCION PRIMARIA DE SALUD. ABSTRACT A descriptive-retrospective study aimed at identifying the factors which influence on useless cytology for the diagnosis belonging to the health area of "5 de Septiembre" Teaching Outpatient Clinic in Consolación del Sur Municipality during the period between January and December 2001 was carried out, 1754 patients underwent on cytological examination, out of them 105 samples were useless and the total of negative cytologies were 1649 which provided an useless rate of 6.3 over the provincial mean, the study showed that the 65.7 % of the cytology was useless due to the onset of vaginal sepsis and the 34.2 % of the cause was because of the poor sample collection, being these two factors the most influential in useless cytology. Besides, it was assessed by means of a skill test that nursing staff has difficulties in putting into effect the program of early detection of cervical cancer. DeCS: VAGINAL SEPSIS, PRIMARY HEALTH CARE
Modified SEIR epidemic model including asymptomatic and hospitalized cases with correct demographic evolution
The aim of this study is to propose a modified Susceptible-Exposed-Infectious-Removed (SEIR) model that describes the time behaviour of symptomatic, asymptomatic and hospitalized patients in an epidemic, taking into account the effect of the demographic evolution. Unlike most of the recent studies where a constant ratio of new individuals is considered, we consider a more correct assumption that the growth ratio is proportional to the total population, following a Logistic law, as is usual in population growth studies for humans and animals. An exhaustive theoretical study is carried out and the basic reproduction number is computed from the model equations. It is proved that if then the disease-free manifold is globally asymptotically stable, that is, the epidemics remits. Global and local stability of the equilibrium points is also studied. Numerical simulations are used to show the agreement between numerical results and theoretical properties. The model is fitted to experimental data corresponding to the pandemic evolution of COVID-19 in the Republic of Cuba, showing a proper behaviour of infected cases which let us think that can provide a correct estimation of asymptomatic cases. In conclusion, the model seems to be an adequate tool for the study and control of infectious diseases
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