Engineering professors' conceptions on basic topics of electromagnetism in Mexico

Electromagnetism is one of the introductory physics subjects common to many engineering programs in Mexico and other countries. There are several studies about students’ misconceptions regarding the contents of electromagnetism courses but the information about teachers’ misconceptions which is one of the main factors that contribute to students’ misconceptions, is not very extensive. It is a fact that teachers, as well as students, have problems with the scientific knowledge of some concepts (Pardhan & Bano, 2001). Since they are responsible for helping students to fully understand and give a proper meaning to these concepts, it is very important to find out what teachers know about these concepts, to generate teacher formation programs that help them in the improvement of their teaching activities. Moreover, most of the existing studies focus on identifying misconceptions about the properties of electric charges (Furió-Mas & Guisasola Aranzabal, 2008), electric field, Gauss’s law, electric current (Hashish et al., 2020) and voltage, but none of them is centered around the basic concepts in electrostatics and the strong relations between them. This work is part of a qualitative research with a descriptive design and presents the results of a 2-tier instrument combined with a semi-structured interview, designed to identify the conceptions that in-service engineering teachers have about the concepts of electrostatic force, electric field, electric potential, and the relation between them, distinguishing between correct conceptions, misconceptions, and lack of knowledge. RESULTS Information about the teachers’ academic training and teaching experience will be presented, correlating this information to the conceptions that teachers have about the basic electrostatics concepts. Due to the academic training and teaching experience that in-service teachers have, predominance of misconceptions over lack of knowledge is expected. REFERENCES Furió-Mas, C., & Guisasola Aranzabal, J. (2008). Dificultades de aprendizaje de los conceptos de carga y de campo eléctrico en estudiantes de bachillerato y universidad. Enseñanza de Las Ciencias. Revista de Investigación y Experiencias Didácticas, 16(1), 131–146. https://doi.org/10.5565/rev/ensciencias.4148. Hashish, A. H., Seyd-Darwish, I., & Tit, N. (2020). Addressing Some Physical Misconceptions in Electrostatics of Freshman Engineering Students. International Journal for Innovation Education and Research, 8(2), 01–07. https://doi.org/10.31686/ijier.vol8.iss2.2161. Pardhan, H., & Bano, Y. (2001). Science teachers’ alternate conceptions about direct-currents. International Journal of Science Education, 23(3), 301–318. https://doi.org/10.1080/095006901750066538

How fair is an equitable distribution?

Envy is a rather complex and irrational emotion. In general, it is very difficult to obtain a measure of this feeling, but in an economical context envy becomes an observable which can be measured. When various individuals compare their possessions, envy arises due to the inequality of their different allocations of commodities and different preferences. In this paper we show that an equitable distribution of goods does not guarantee a state of fairness between agents and in general that envy cannot be controlled by tuning the distribution of goods.Comment: 16 pages, 8 figures, LaTEX; typos added; minor changes in plots; two new plots added; references added; minor changes in the acknowledgment

Measuring online teaching service quality in higher education in the COVID-19 environment

The use of the Internet to develop new technologies has generated a considerable change in teaching and student learning in higher education. The pandemic caused by COVID-19 has forced universities to switch from face-to-face to online instruction. Furthermore, this transfer process was planned and executed quickly, with urgent redesigns of courses originally conceived for live teaching. The aim of this work is to measure the service quality of online teaching delivered during the COVID- 19 period. The methodology was based on an importance-performance analysis using a structural equations model. The data were obtained from a sample of 467 students attending a university in southern Spain. The results reveal five priority attributes of online teaching that need to be improved in order to enhance the service quality of the virtual instruction provided to students. Universities need to redefine their online format by integrating methodological and technological decisions and involving collaboration between teachers, students and administration staff and services. The results do not apply to educational institutions that exclusively teach courses online, but to those institutions that had to rapidly adapt, and shift course material originally designed for face-to-face training

Cuantificación del aporte contaminante gaseoso producto de las operaciones de GSE en plataforma: metodología según tiempos operativos 

Las infraestructuras aeroportuarias, a la vez de ser centros fundamentales de actividad, impulsores de la economía, del desarrollo social y cultural, así como vertebradores e integradores de regiones y estados, son también elementos que interaccionan con el medio ambiente sobre el que se asientan. La necesidad de hacer compatible el desarrollo del transporte aéreo con la conservación de los valores naturales y de la calidad de vida en el entorno aeroportuario precisa un modelo de actuación basado en el equilibrio entre los factores económicos, sociales y ambientales, que permita el acercamiento a un modelo sostenible de desarrollo. Uno de los objetivos de la OACI respecto al medio ambiente es el de limitar o reducir las repercusiones de las emisiones de la aviación en la calidad del aire local. Los contaminantes de las aeronaves que causan preocupación respecto a este son las emisiones gaseosas que actualmente se controlan para la certificación de motores de aeronave en el marco del Anexo 16, Volumen II, incluidos los óxidos de nitrógeno (NOx), el monóxido de carbono (CO) y los hidrocarburos sin quemar (HC). También se reconoce que las emisiones de contaminantes secundarios (VOCs) y la materia en partículas (PM) de las aeronaves pueden tener efectos locales adversos [1]. La cuantificación de los gases regulados por OACI en el Anexo 16 constituye el paso previo para la determinación de las concentraciones atmosféricas previstas, siendo esta la base de los estudios de dispersión y consecuencias sobre la calidad del aire local (LAQ) utilizados para demostrar el cumplimiento de los reglamentos o normas requeridos. La masa total emitida no tiene en cuenta la mezcla en la atmósfera que determina las concentraciones locales, ni tampoco cuánta masa se mezcla en el aire en un tiempo determinado, de allí la necesidad de realizar un estudio de dispersión gaseosa y mediciones in-situ para cuantificar la población afectada [5]. La magnitud de la contaminación aérea y su impacto en la calidad del aire puede variar de un aeropuerto a otro según el emplazamiento y la índole de las instalaciones, servicios en rampa y servicios de transporte público o privados que presten servicio al mismo. La necesidad de reducir la contaminación aérea que producen los vehículos motorizados del aeropuerto, el tráfico de acceso y otros, ha atraído la atención de la mayoría de los gobiernos y de algunas organizaciones intergubernamentales. De acuerdo con el primer informe técnico de la IPCC destinado específicamente al sector del transporte aéreo la cuota parte de las emisiones totales de CO2 antropogénicas es del 2%. Teniendo en cuenta la totalidad de los gases emitidos, su interacción con la atmosfera y su respectivo impacto en el cambio climático el valor alcanzado es de un 3,5% en el forzamiento radiativo mundial antropogénico. [6]. De acuerdo con distintas proyecciones de tráfico de la OACI se estima que las emisiones de CO2 producto del transporte aéreo internacional aumentarán entre 111 y 144 por ciento entre 2005 y 2025 (es decir, de 416 Mt a entre 876 y 1013 Mt). [7] La cuantificación de emisiones de dióxido de carbono, tanto en niveles crucero como en las operaciones aeroportuarias, posee un método de cálculo demostrado y aceptados [8] [9]. Se han publicado distintos estudios, presentando inventarios específicos a nivel nacional [10], como a nivel internacional en base a estimaciones de trafico de OACI [11] [12] [13]

Leishmanicidal Activity of Nine Novel Flavonoids from Delphinium staphisagria

Objectives. To evaluate the in vitro leishmanicidal activity of nine flavonoid derivatives from Delphinium staphisagria against L. infantum and L. braziliensis. Design and Methods. The in vitro activity of compounds 1–9 was assayed on extracellular promastigote and axenic amastigote forms and on intracellular amastigote forms of the parasites. Infectivity and cytotoxicity tests were carried on J774.2 macrophage cells using Glucantime as the reference drug. The mechanisms of action were analysed performing metabolite excretion and transmission electronic microscope ultrastructural alteration studies. Results. Nine flavonoids showed leishmanicidal activity against promastigote as well as amastigote forms of Leishmania infantum and L. braziliensis. These compounds were nontoxic to mammalian cells and were effective at similar concentrations up to or lower than that of the reference drug (Glucantime). The results showed that 2″-acetylpetiolaroside (compound 8) was clearly the most active. Conclusion. This study has demonstrated that flavonoid derivatives are active against L. infantum and L. braziliensis

Rotational properties of the O-type star population in the Tarantula region

The 30 Doradus (30\,Dor) region in the Large Magellanic Cloud (also known as the Tarantula Nebula) is the nearest massive starburst region, containing the richest sample of massive stars in the Local Group. It is the best possible laboratory to investigate aspects of the formation and evolution of massive stars. Here, we focus on rotation which is a key parameter in the evolution of these objects. We establish the projected rotational velocity, $v_{e}\sin i$, distribution of an unprecedented sample of 216 radial velocity constant ($\rm{\Delta RV\, \leq\, 20 \,km s^{-1}}$) O-type stars in 30\,Dor observed in the framework of the VLT-FLAMES Tarantula Survey (VFTS). The distribution of $v_{e}\sin i$ shows a two-component structure: a peak around 80 $\rm{km s^{-1}}$ and a high-velocity tail extending up to $\sim$600 $\rm{km s^{-1}}$. Around 75% of the sample has 0 $\leq\, v_{e}\sin i \leq$ 200 $\rm{km s^{-1}}$ with the other 25% distributed in the high-velocity tail. The presence of the low-velocity peak is consistent with that found in other studies of late-O and early-B stars. The high-velocity tail is compatible with expectations from binary interaction synthesis models and may be predominantly populated by post-binary interaction, spun-up, objects and mergers. This may have important implications for the nature of progenitors of long-duration gamma ray bursts.Comment: 4 pages, 1 figure. Conference proceedings article: Massive stars: from alpha to Omega, 10-14 June 2013, Rhodes, Greec

Rotational velocities of single and binary O-type stars in the Tarantula Nebula

Rotation is a key parameter in the evolution of massive stars, affecting their evolution, chemical yields, ionizing photon budget, and final fate. We determined the projected rotational velocity, $v_e\sin i$, of $\sim$330 O-type objects, i.e. $\sim$210 spectroscopic single stars and $\sim$110 primaries in binary systems, in the Tarantula nebula or 30 Doradus (30\,Dor) region. The observations were taken using VLT/FLAMES and constitute the largest homogeneous dataset of multi-epoch spectroscopy of O-type stars currently available. The most distinctive feature of the $v_e\sin i$ distributions of the presumed-single stars and primaries in 30 Dor is a low-velocity peak at around 100\,$\rm{km s^{-1}}$. Stellar winds are not expected to have spun-down the bulk of the stars significantly since their arrival on the main sequence and therefore the peak in the single star sample is likely to represent the outcome of the formation process. Whereas the spin distribution of presumed-single stars shows a well developed tail of stars rotating more rapidly than 300\,$\rm{km s^{-1}}$, the sample of primaries does not feature such a high-velocity tail. The tail of the presumed-single star distribution is attributed for the most part -- and could potentially be completely due -- to spun-up binary products that appear as single stars or that have merged. This would be consistent with the lack of such post-interaction products in the binary sample, that is expected to be dominated by pre-interaction systems. The peak in this distribution is broader and is shifted toward somewhat higher spin rates compared to the distribution of presumed-single stars. Systems displaying large radial velocity variations, typical for short period systems, appear mostly responsible for these differences.Comment: 6 pages, 3 figures, Proceedings IAU Symposium No. 307, 2014, 'New windows on massive stars: asteroseismology, interferometry, and spectropolarimetry