10,487 research outputs found
HT Cas - eclipsing dwarf nova during its superoutburst in 2010
We present results of a world-wide observing campaign of the eclipsing dwarf
nova - HT Cas during its superoutburst in November 2010. Using collected data
we were able to conduct analysis of the light curves and we calculated
diagrams.
The CCD photometric observations enabled us to derive the superhump period
and with the timings of eclipses the orbital period was calculated. Based on
superhump and orbital period estimations the period excess and mass ratio of
the system were obtained
IX Draconis - a curious ER UMa-type dwarf nova
We report results of an extensive world-wide observing campaign devoted to a
very active dwarf nova star - IX Draconis. We investigated photometric
behaviour of the system to derive its basic outburst properties and understand
peculiarities of IX Dra as well as other active cataclysmic variables, in
particular dwarf novae of the ER Uma-type. In order to measure fundamental
parameters of the system, we carried out analyses of the light curve, O-C
diagram, and power spectra. During over two months of observations we detected
two superoutbursts and several normal outbursts. The V magnitude of the star
varied in the range 14.6 - 18.2 mag. Superoutbursts occur regularly with the
supercycle length of 58.5+/-0.5 d. When analysing data over the past 20 years,
we found that the supercycle length is increasing at a rate of P_dot = 1.8 *
10^{-3}. Normal outbursts appear to be irregular, with typical occurrence times
in the range 3.1 - 4.1 d. We detected a double-peaked structure of superhumps
during superoutburst, with the secondary maximum becoming dominant near the end
of the superoutburst. The mean superhump period observed during superoutbursts
equals 0.066982(36) d, which is constant over the last two decades of
observations. Based on the power spectrum analysis, the evaluation of the
orbital period was problematic. We found two possible values: the first one,
0.06641(3) d, which is in agreement with previous studies and our O-C analysis
(0.06646(2) d), and the second one, 0.06482(3) d, which is less likely. The
evolutionary status of the object depends dramatically on the choice between
these two values. A spectroscopic determination of the orbital period is
needed. We updated available information on ER UMa-type stars and present a new
set of their basic statistics. Thereby, we provide evidence that this class of
stars is not uniform.Comment: Accepted for publication in MNRAS; 15 pages, 15 figures, 6 tables;
typo correcte
Education on Sustainable Development Goals: Geographical Perspectives for Gender Equality in Sustainable Cities and Communities
Because of its interdisciplinary approach as a social science directly related to the natural sciences, geography is the academic discipline and school subject that equips students well with knowledge, skills, and values related to education on sustainable development goals. This study is part of the results of MyGEO, a project funded by the European Commission, and it is based on a collaborative mapping of streets named after women in a medium-sized city (Zaragoza, Spain), in connection with the international initiative GeoChicas (GeoGirls) on OpenStreetMap. Its main objective is to obtain evidence to emphasize, through public and digital space, gender equality and the empowerment of women in teacher education by means of their achievements. The learning methodology consists of (i) standardization and correction of alphanumeric information referring to street names contained in the OpenStreetMap spatial database that identify gender and (ii) linking and creating thematic information through Wikipedia editing. The results show that Zaragoza is at the top of the ranking of Spanish and Latin American cities mapped to date in the “Women’s Streets” viewer, with 18% of the streets named after women, compared to the average 15% in the rest of the 30 cities involved in GeoChicas. The direct participation of trainee primary and secondary schoolteachers in this project makes it possible to consolidate a narrative as well as a specific instructional design on education for sustainable development, particularly on SDG number 5 (gender balance) and SDG number 11 (sustainable cities and communities). © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Mobile learning for sustainable development and environmental teacher education
Outdoor learning has, for a long time, been an important instructional resource in school education, usually embedded in the natural sciences and social sciences curricula. Teaching geography, geology, or biology beyond the traditional classroom allows students to interact with physical and social environments for meaningful learning. Mobile devices that are based on geospatial technologies have provided more accurate data, but also a combined instructional design with other WebGIS, map viewers, or geographic information system (GIS) layers, which are useful to foster education for sustainable development. This paper analyzes the applications of mobile learning based on citizen science and volunteer geographic information, but also on the growing awareness that citizens and educators need a set of digital competencies to enhance and innovate lifelong learning and active citizenship. The empirical research aims to measure teacher–training experience, highlighting the potential of mobile devices and their applications in environmental education. Data collected from the research and results prove the positive impact of mobile learning in environmental education. Finally, a discussion about mobile learning and education for sustainable development is provided
Discretization-related issues in the KPZ equation: Consistency, Galilean-invariance violation, and fluctuation--dissipation relation
In order to perform numerical simulations of the KPZ equation, in any
dimensionality, a spatial discretization scheme must be prescribed. The known
fact that the KPZ equation can be obtained as a result of a Hopf--Cole
transformation applied to a diffusion equation (with \emph{multiplicative}
noise) is shown here to strongly restrict the arbitrariness in the choice of
spatial discretization schemes. On one hand, the discretization prescriptions
for the Laplacian and the nonlinear (KPZ) term cannot be independently chosen.
On the other hand, since the discretization is an operation performed on
\emph{space} and the Hopf--Cole transformation is \emph{local} both in space
and time, the former should be the same regardless of the field to which it is
applied. It is shown that whereas some discretization schemes pass both
consistency tests, known examples in the literature do not. The requirement of
consistency for the discretization of Lyapunov functionals is argued to be a
natural and safe starting point in choosing spatial discretization schemes. We
also analyze the relation between real-space and pseudo-spectral discrete
representations. In addition we discuss the relevance of the Galilean
invariance violation in these consistent discretization schemes, and the
alleged conflict of standard discretization with the fluctuation--dissipation
theorem, peculiar of 1D.Comment: RevTex, 23pgs, 2 figures, submitted to Phys. Rev.
Interaction potentials for soft and hard ellipsoids
Using results from colloid science we derive interaction potentials for
computer simulations of mixtures of soft or hard ellipsoids of arbitrary shape
and size. Our results are in many respects reminicent of potentials of the
Gay-Berne type but have a well-defined microscopic interpretation and no
adjustable parameters. Since our potentials require the calculation of similar
variables, the modification of existing simulation codes for Gay-Berne
potentials is straightforward. The computational performance should remain
unaffected.Comment: 8 pages, 4 figure
Mixing Time Scales in a Supernova-Driven Interstellar Medium
We study the mixing of chemical species in the interstellar medium (ISM).
Recent observations suggest that the distribution of species such as deuterium
in the ISM may be far from homogeneous. This raises the question of how long it
takes for inhomogeneities to be erased in the ISM, and how this depends on the
length scale of the inhomogeneities. We added a tracer field to the
three-dimensional, supernova-driven ISM model of Avillez (2000) to study mixing
and dispersal in kiloparsec-scale simulations of the ISM with different
supernova (SN) rates and different inhomogeneity length scales. We find several
surprising results. Classical mixing length theory fails to predict the very
weak dependence of mixing time on length scale that we find on scales of
25--500 pc. Derived diffusion coefficients increase exponentially with time,
rather than remaining constant. The variance of composition declines
exponentially, with a time constant of tens of Myr, so that large differences
fade faster than small ones. The time constant depends on the inverse square
root of the supernova rate. One major reason for these results is that even
with numerical diffusion exceeding physical values, gas does not mix quickly
between hot and cold regions.Comment: 23 pages, 14 figures that include 7 simulation images and 19 plots,
accepted for publication at Ap
On the Hamilton-Jacobi Theory for Singular Lagrangian Systems
We develop a Hamilton-Jacobi theory for singular lagrangian systems using the
Gotay-Nester-Hinds constraint algorithm. The procedure works even if the system
has secondary constraints.Comment: 36 page
Multidisciplinary teaching of Biotechnology and Omics sciences
In the last years, there was a great boom in the Omics fields that have developed as multidisciplinary
sciences. They use laboratory techniques related to Biology and Chemistry but also Bioinformatics
tools. However, the developmental progress of these disciplines has led that much of undergraduate
studies related to Biology have curricula that become outdated. From this point of view, it is
necessary to focus the students to the fundamentals and techniques of complementary disciplines that
will be essentials for the understanding of the Omics sciences. In the present work, we have
developed a new teaching approach for Biochemistry, Biology and Bioinformatics students. They
formed interdisciplinary working groups. These groups have prepared and presented
communications about different techniques or methods in Molecular Biology, Omics or
Bioinformatics participating in a technical meeting. This learning strategy “I do and I learn” has
enabled to the students a first contact with the scientific communication including the approach to the
scientific literature to acquire technical knowledge. The cooperation between students from different
disciplines has enriched their point of view and even has been used in some practical master’s works.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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