8,721 research outputs found
On algebraic classification of quasi-exactly solvable matrix models
We suggest a generalization of the Lie algebraic approach for constructing
quasi-exactly solvable one-dimensional Schroedinger equations which is due to
Shifman and Turbiner in order to include into consideration matrix models. This
generalization is based on representations of Lie algebras by first-order
matrix differential operators. We have classified inequivalent representations
of the Lie algebras of the dimension up to three by first-order matrix
differential operators in one variable. Next we describe invariant
finite-dimensional subspaces of the representation spaces of the one-,
two-dimensional Lie algebras and of the algebra sl(2,R). These results enable
constructing multi-parameter families of first- and second-order quasi-exactly
solvable models. In particular, we have obtained two classes of quasi-exactly
solvable matrix Schroedinger equations.Comment: LaTeX-file, 16 pages, submitted to J.Phys.A: Math.Ge
Genetic study in patients operated dentally and anesthetized with articaine-epinephrine
Aims: In this study we wanted to figure out if there was a correlation between OPRM1 N40D, TRPV1 I316M, TRPV1 I585V, NOS3 −786T>C and IL6 −174C>G polymorphisms and the response to locally applied articaine-epinephrine anesthetic.
Methods: In this observational study, 114 oral cell samples of patients anesthetized with articaine-epinephrine (54 from men 60 from women), were collected from dental centers in Madrid (Spain). High molecular weight DNA was obtained from oral mucosa cells. The analysis of OPRM1 N40D (rs1799971), TRPV1 I316M (rs222747), TRPV1 I585V (rs8065080) and IL6 −174C>G polymorphism was performed through real-time PCR allelic discrimination using TaqMan probes. Polymorphism NOS3 −786T> C (rs2070744) was analyzed using RFLP-PCR.
Results: The studied polymorphisms are involved neither in the response to the anesthetic, nor in the intensity of perceived dental pain. However, in a subset of female patients we found that TRPV1 I316M was associated with a delayed onset of anesthesia.
Conclusions: There is no association among these polymorphisms and the time elapsed between the application of the anesthetic and the onset of its effect
HH 223: a parsec-scale H2 outflow in the star-forming region L723
The dark cloud Lynds 723 (L723) is a low-mass star-forming region where one
of the few known cases of a quadrupolar CO outflow has been reported. Two
recent works have found that the radio continuum source VLA 2, towards the
centre of the CO outflow, is actually a multiple system of young stellar
objects (YSOs). Several line-emission nebulae that lie projected on the
east-west CO outflow were detected in narrow-band Halpha and [SII] images. The
spectra of the knots are characteristic of shock-excited gas (Herbig-Haro
spectra), with supersonic blueshifted velocities, which suggests an optical
outflow also powered by the VLA 2 YSO system of L723. We imaged a field of ~5'
X 5' centred on HH 223, which includes the whole region of the quadrupolar CO
outflow with nir narrow-band filters . The H2 line-emission structures appear
distributed over a region of 5.5' (0.5 pc for a distance of 300 pc) at both
sides of the VLA 2 YSO system, with an S-shape morphology, and are projected
onto the east-west CO outflow. Most of them were resolved in smaller knotty
substructures. The [FeII] emission only appears associated with HH 223. An
additional nebular emission from the continuum in Hc and Kc appears associated
with HH 223-K1, the structure closest to the VLA 2 YSO system, and could be
tracing the cavity walls. We propose that the H2 structures form part of a
large-scale near-infrared outflow, which is also associated with the VLA 2 YSO
system. The current data do not allow us to discern which of the YSOs of VLA 2
is powering this large scale optical/near-infrared outflow.Comment: Accepted for A&A http://dx.doi.org/10.1051/0004-6361/201015125 12
pages, 9 figure
LASER WAVELENGTH MEASUREMENTS USING A QUARTZ PLATE AND FARADAY EFFECT
The authors performed a polarimetric prototype for wavelength measurements. In the design both Faraday rotators acting for modulation of the incoming laser light and also as compensator, allow together with a quartz plate, a precise measurement of laser wavelength from 400 to 900 nm, with a resolution better than 0.1 nm. Equations and graphics current versus lambda for a quartz tungsten halogen lamp are presented for sensor adjustments. It is also presented a signal to noise analysis and a comparison with a conventional method. En el presente trabajo se describe el diseño de un prototipo de medidor de longitud de onda polarimétrico. En el diseño los rotadores de Faraday actúan en la modulación y compensación de la luz incidente, estos unidos a una placa de cuarzo permite la medición de longitudes de onda entre 400 y 900 nm, con una resolución mejor que 0.1 nm. Las ecuaciones y los gráficos de corriente contra la longitud de onda son presentados para ajustes de los sensores. Además es presentado un análisis de la relación señal-ruido y una comparación con el método tradicional
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
Mean field theory of chaotic insect swarms
The harmonically confined Vicsek model displays qualitative and quantitative features observed in natural insect swarms. It exhibits a scale-free transition between single and multicluster chaotic phases. Finite-size scaling indicates that this unusual phase transition occurs at zero confinement [Phys. Rev. E 107, 014209 (2023)]. While the evidence of the scale-free-chaos phase transition comes from numerical simulations, here we present its mean-field theory. Analytically determined critical exponents are those of the Landau theory of equilibrium phase transitions plus dynamical critical exponent
z
=
1
and a new critical exponent
φ
=
0.5
for the largest Lyapunov exponent. The phase transition occurs at zero confinement and noise in the mean-field theory. The noise line of zero largest Lyapunov exponents informs observed behavior: (i) the qualitative shape of the swarm (on average, the center of mass rotates slowly at the rate marked by the winding number and its trajectory fills compactly the space, similarly to the observed condensed nucleus surrounded by vapor) and (ii) the critical exponents resemble those observed in natural swarms. Our predictions include power laws for the frequency of the maximal spectral amplitude and the winding number.This work has been supported by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación Grants No. PID2020-112796RB-C21 ( R.G.-A.) and No. PID2020-112796RB-C22 (L.L.B.), by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M23), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation). R.G.-A. acknowledges support from the Ministerio de Economía y Competitividad of Spain through the Formación de Doctores program Grant No. PRE2018-083807 cofinanced by the European Social Fund
Reliability evaluation of III-V concentrator solar cells
Concentrator solar cells have been proposed as an interesting way of reducing the cost of photovoltaic electricity. However, in order to compete with conventional solar modules it is necessary not only to reduce costs but also to evaluate and increase the present reliability. Concentrator solar cells work at higher temperature, solar radiation and current stress than conventional solar cells and a carefully reliability analysis is needed. In this paper a reliability analysis procedure, that is being developed, is presented
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