Fiscal Decentralization in Mexico: The Bailout Problem

The purpose of this paper is to identify and analyze the determinants and consequences of bailing out states, in particular, those observed in Mexico. This work suggests that the explicit generalized bailout carried out by the federal government in Mexico in 1995 created a moral hazard problem. Another result of the analysis is that the existing institutional-legal framework is not adequate, since it provides incentives for states to borrow and for banks to lend without evaluating the risk of the project. Likewise, the importance of the state is a major determinant in providing bailout transfers. Also, the more fiscal need a state government has when the state government is incapable of adjusting its expenditure, the more likely the state to get an extraordinary transfer during the period of study. On the other hand, political variables are not an important determinant of a bailout, except, perhaps, when there are state elections. It is also shown that excessive indebtedness of local states may have equity implications as well: bailouts tend to be highly regressive, as the poorer—and less indebted—states receive much less in extraordinary resources.

Análisis de la eficacia y la cultura escolar en el subsistema de universidades tecnológicas de México: hacia un modelo de desarrollo docente

En este trabajo se presentan los resultados preliminares de un análisis de la eficacia escolar de las Universidades Tecnológicas en México (nivel 5B CINE, UNESCO) y su relación con la cultura escolar que prevalece en ellas. A partir de un estudio de eficacia que incluyó los datos de exámenes de ingreso y de egreso aplicados por el Centro Nacional de Evaluación para la Educación Superior (CENEVAL), en el periodo 2000-2006 en las Universidades Tecnológicas de todo el país, se revisan algunas características de la cultura escolar de los estudiantes, definidas a partir de un cuestionario de contexto

Induced Monolayer Altermagnetism in MnP(S,Se)3_3 and FeSe

Altermagnets (AM) are a recently discovered third class of collinear magnets, distinctly different from conventional ferromagnets (FM) and antiferromagnets (AF). AM have been actively researched in the last few years, but two aspects so far remain unaddressed: (1) Are there realistic 2D single-layer altermagnets? And (2) is it possible to functionalize a conventional AF into AM by external stimuli? In this paper we address both issues by demonstrating how a well-known 2D AF, MnP(S,Se)$_3$ can be functionalized into strong AM by applying out-of-plane electric field. Of particular interest is that the induced altermagnetism is of a higher even-parity wave symmetry than expected in 3D AM with similar crystal symmetries. We confirm our finding by first-principles calculations of the electronic structure and magnetooptical response. We also propose that recent observations of the time-reversal symmetry breaking in the famous Fe-based superconducting chalchogenides, either in monolayer form or in the surface layer, may be related not to an FM, as previously assumed, but to the induced 2D AM order. Finally, we show that monolayer FeSe can simultaneously exhibit unconventional altermagnetic time-reversal symmetry breaking and quantized spin Hall conductivity indicating possibility to research an intriquing interplay of 2D altermagnetism with topological and superconducting states within a common crystal-potential environment.Comment: 11 pages, 7 figure

Chiralities of nodal points along high symmetry lines with screw rotation symmetry

Screw rotations in nonsymmorphic space group symmetries induce the presence of hourglass and accordion shape band structures along screw invariant lines whenever spin-orbit coupling is nonnegligible. These structures induce topological enforced Weyl points on the band intersections. In this work we show that the chirality of each Weyl point is related to the representations of the cyclic group on the bands that form the intersection. To achieve this, we calculate the Picard group of isomorphism classes of complex line bundles over the 2-dimensional sphere with cyclic group action, and we show how the chirality (Chern number) relates to the eigenvalues of the rotation action on the rotation invariant points. Then we write an explicit Hamiltonian endowed with a cyclic action whose eigenfunctions restricted to a sphere realize the equivariant line bundles described before. As a consequence of this relation, we determine the chiralities of the nodal points appearing on the hourglass and accordion shape structures on screw invariant lines of the nonsymmorphic materials PI3 (SG: P63), Pd3N (SG: P6322), AgF3 (SG: P6122) and AuF3 (SG: P6122), and we corroborate these results with the Berry curvature and symmetry eigenvalues calculations for the electronic wavefunction.Comment: 10 pages, 4 figure

Dimethylformamide Impurities as Propylene Polymerization Inhibito

This research study examined how the use of dimethylformamide (DMF) as an inhibitor af fects the propylene polymerization process when using a Ziegler–Natta catalyst. Several experiments were carried out using TiCl4/MgCl2 as a catalyst, aluminum trialkyl as a cocatalyst, and different amounts of DMF. Then, we analyzed how DMF influences other aspects of the process, such as catalyst activity, molecular weight, and the number of branches in the polymer chains obtained, using experimental and computational methods. The results revealed that as the DMF/Ti ratio increases, the catalyst activity decreases. From a concentration of 5.11 ppm of DMF, a decrease in catalyst activity was observed, ranging from 45 TM/Kg to 44 TM/Kg. When the DMF concentration was increased to 40.23 ppm, the catalyst activity decreased to 43 TM/Kg, and with 75.32 ppm, it dropped even further to 39 TM/Kg. The highest concentration of DMF evaluated, 89.92 ppm, resulted in a catalyst productivity of 36.5 TM/Kg and lost productivity of 22%. In addition, significant changes in the polymer’s melt flow index (MFI) were noted as the DMF concentration increased. When 89.92 ppm of DMF was added, the MFI loss was 75%, indicating a higher flowability of the poly mer. In this study, it was found that dimethylformamide (DMF) exhibits a strong affinity for the titanium center of a Ziegler–Natta (ZN) catalyst, with an adsorption energy (Ead) of approximately −46.157 kcal/mol, indicating a robust interaction. This affinity is significantly higher compared to propylene, which has an Ead of approximately −5.2 kcal/mol. The study also revealed that the energy gap between the highest occupied molecular orbital (HOMO) of DMF and the lowest unoccupied molecular orbital (SOMO) of the Ziegler–Natta (ZN) catalyst is energetically favorable, with a value of approximately 0.311 eV.Universidad Tecnológica de Bolivar, Universidad de Cartagena, Universidad de la Cost

Parts per Million of Propanol and Arsine as Responsible for the Poisoning of the Propylene Polymerization Reactio

Polypropylene synthesis is a critical process in the plastics industry, where control of catalytic activity is essential to ensure the quality and performance of the final product. In this study, the effect of two inhibitors, propanol and arsine, on the properties of synthesized polypropylene was investigated. Experiments were conducted using a conventional catalyst to polymerize propylene, and different concentrations of propanol and arsine were incorporated into the process. The results revealed that the addition of propanol led to a significant decrease in the Melt Flow Index (MFI) of the resulting polypropylene. The reduction in the MFI was most notable at a concentration of 62.33 ppm propanol, suggesting that propanol acts as an effective inhibitor by slowing down the polymerization rate and thus reducing the fluidity of the molten polypropylene. On the other hand, introducing arsine as an inhibitor increased the MFI of polypropylene. The maximum increase in the MFI was observed at a concentration of 0.035 ppm arsine. This suggests that small amounts of arsine affect the MFI and Mw of the produced PP. Regarding the catalyst productivity, it was found that as the concentration of propanol in the sample increased (approximately seven ppm), there was a decrease in productivity from 45 TM/kg to 44 TM/kg. Starting from 10 ppm, productivity continued to decline, reaching its lowest point at 52 ppm, with only 35 MT/kg. In the case of arsine, changes in catalyst productivity were observed at lower concentrations than with propanol. Starting from about 0.006 ppm, productivity decreased, reaching 39 MT/kg at a concentration of 0.024 ppm and further decreasing to 36 TM/kg with 0.0036 ppm. Computational analysis supported the experimental findings, indicating that arsine adsorbs more stably to the catalyst with an energy of −60.8 Kcal/mol, compared to propanol (−46.17 Kcal/mol) and isobutyl (−33.13 Kcal/mol). Analyses of HOMO and LUMO orbitals, as well as reactivity descriptors, such as electronegativity, chemical potential, and nucleophilicity, shed light on the potential interactions and chemical reactions involving inhibitors. Generated maps of molecular electrostatic potential (MEP) illustrated the charge distribution within the studied molecules, further contributing to the understanding of their reactivity. The computational results supported the experimental findings and provided additional information on the molecular interactions between the inhibitors and the catalyst, shedding light on the possible modes of inhibition. Solubles in xylene values indicate that both propanol and arsine affect the polymer’s morphology, which may have significant implications for its properties and final applications

Análisis crítico del manuscrito El Cacique de Andacollo, de Pablo Galleguillos (1931)

O ensaio a seguir estuda criticamente o manuscrito El Cacique de Andacollo, do historiador chileno dom Pablo Galleguillos. Um documento que se manteve guardado por quase um século por seus familiares, mas inacessível para a comunidade científica, e que foi incluído recentemente numa coletânea com as principais obras do autor. Primeiro se realizou uma breve revisão dos antecedentes bibliográficos que tratam o assunto central trabalhado no manuscrito e, na seção seguinte, analisou-se em profundidade o texto. A análise do texto enfocou-se na revisão de suas partes e conteúdos principais, no exame da motivação do autor e no estudo de sua temática central. Sublinha-se, assim mesmo, que a análise de conteúdos vinculou o texto com as principais fontes e estudos de referência nas disciplinas preocupadas tanto com a produção da escrita quanto com as formas de ler que existiam no período onde foi feito o manuscrito: no final do século XIX e começo do século XX.El siguiente ensayo analiza críticamente el manuscrito El Cacique de Andacollo, escrito en 1931 por el historiador chileno don Pablo Galleguillos, documento que permaneció casi un siglo en manos familiares pero desconocido para la comunidad científica, siendo recientemente publicado en la reedición de una compilación sobre el autor. Se realiza al inicio una brevísima revisión de los antecedentes bibliográficos que existen sobre el tema central tratado por el manuscrito original, para, en la sección siguiente, analizar críticamente el texto a partir de una revisión de sus partes y contenidos principales, de la motivación del autor y del tema central del escrito, vinculando críticamente este importante manuscrito con el mapa de fuentes y estudios de referencias disciplinarias sobre la producción escritural y las formas lectoras en la transición del siglo XIX al XX.The following essay critically analyzes the manuscript El Cacique de Andacollo, written in 1931 by Chilean historian Pablo Galleguillos, a document that remained almost a century in familiar hands but unknown to the scientific community, being recently published in the re-edition of a compilation about the author. At the beginning, a very brief review of the bibliographical antecedents that exist on the central theme treated by the original manuscript is made, in order to, in the following section, critically analyze the text from a review of its main parts and contents, of the author’s motivation and of the central theme of the writing, critically linking this important manuscript with the map of sources and studies of disciplinary references on the scriptural production and the reading forms in the transition from the 19th to the 20th century

Crystal Hall effect in Collinear Antiferromagnets

Electrons, commonly moving along the applied electric field, acquire in certain magnets a dissipationless transverse velocity. This spontaneous Hall effect, discovered more than a century ago, has been understood in terms of the time-reversal symmetry breaking by the internal spin-structure of a ferromagnetic, noncolinear antiferromagnetic or skyrmionic form. Here we identify previously overlooked robust Hall effect mechanism arising from collinear antiferromagnetism combined with nonmagnetic atoms at non-centrosymmetric positions. We predict a large magnitude of this crystal Hall effect in a room-temperature collinear antiferromagnet RuO$_2$ and catalogue, based on our symmetry rules, extensive families of material candidates. We show that the crystal Hall effect is accompanied by the possibility to control its sign by the crystal chirality. We illustrate that accounting for the full magnetization density distribution instead of the simplified spin-structure sheds new light on symmetry breaking phenomena in complex magnets and opens an alternative avenue towards quantum materials engineering for low-dissipation nanoelectronics.Comment: 21 pages, 5 figure