Binomial Ideals and Congruences on Nn

Producción CientíficaA congruence on Nn is an equivalence relation on Nn that is compatible with the additive structure. If k is a field, and I is a binomial ideal in k[X1,…,Xn] (that is, an ideal generated by polynomials with at most two terms), then I induces a congruence on Nn by declaring u and v to be equivalent if there is a linear combination with nonzero coefficients of Xu and Xv that belongs to I. While every congruence on Nn arises this way, this is not a one-to-one correspondence, as many binomial ideals may induce the same congruence. Nevertheless, the link between a binomial ideal and its corresponding congruence is strong, and one may think of congruences as the underlying combinatorial structures of binomial ideals. In the current literature, the theories of binomial ideals and congruences on Nn are developed separately. The aim of this survey paper is to provide a detailed parallel exposition, that provides algebraic intuition for the combinatorial analysis of congruences. For the elaboration of this survey paper, we followed mainly (Kahle and Miller Algebra Number Theory 8(6):1297–1364, 2014) with an eye on Eisenbud and Sturmfels (Duke Math J 84(1):1–45, 1996) and Ojeda and Piedra Sánchez (J Symbolic Comput 30(4):383–400, 2000).National Science Foundation (grant DMS-1500832)Ministerio de Economía, Industria y Competitividad (project MTM2015-65764-C3-1)Junta de Extremadura (grupo de investigación FQM-024

Examining the Myth of Accountability, High-Stakes Testing, and the Achievement Gap

In this article we outline how notions of accountability and the achievement gap have relied upon the massive expansion of high-stakes exams in our nation’s schools. Texas-style test and punish accountability manifested in various ways within schools and school culture across the nation via NCLB, which undermined notions of trust within education. More than decade of national education policy focused on high-stakes testing and accountability—despite that the fact that the rise of high-stakes testing also involved considerable legal, ethical, and social considerations. We argue the practice of spending large amounts of time on test preparation and test taking must be reversed lest we continue on the path of maintaining schools solely as machinery for stratification. We conclude that market- and business-oriented ideology, has reinforced the racist under- and overtones of testocracy in the United States and has neither closed the achievement gap nor fomented meaningful accountability or success

Triple-Star Candidates Among the Kepler Binaries

We present the results of a search through the photometric database of eclipsing Kepler binaries (Prsa et al. 2011; Slawson et al. 2011) looking for evidence of hierarchical triple star systems. The presence of a third star orbiting the binary can be inferred from eclipse timing variations. We apply a simple algorithm in an automated determination of the eclipse times for all 2157 binaries. The "calculated" eclipse times, based on a constant period model, are subtracted from those observed. The resulting O-C (observed minus calculated times) curves are then visually inspected for periodicities in order to find triple-star candidates. After eliminating false positives due to the beat frequency between the ~1/2-hour Kepler cadence and the binary period, 39 candidate triple systems were identified. The periodic O-C curves for these candidates were then fit for contributions from both the classical Roemer delay and so-called "physical" delay, in an attempt to extract a number of the system parameters of the triple. We discuss the limitations of the information that can be inferred from these O-C curves without further supplemental input, e.g., ground-based spectroscopy. Based on the limited range of orbital periods for the triple star systems to which this search is sensitive, we can extrapolate to estimate that at least 20% of all close binaries have tertiary companions.Comment: 19 pages, 13 figures, 3 tables; ApJ, 2013, 768, 33; corrected Fig. 7, updated references, minor fixes to tex

Interdependencies between variables in fatigue analysis of a weight- optimised naval ship optimised naval ship

Modern warships are often constructed from aluminium alloys or high tensile steel, and their increasing range of operational roles indicates exposure to harsh seaway loads including slamming. These factors can lead to fatigue cracking, which can reduce operational availability. The objective of the present study is to improve understanding of the influence of variables in the fatigue analysis of a weight-optimised warship. The objective is met by analysing hull monitoring data acquired from a 56 m naval aluminium patrol boat, to determine the long-term importance of slamming and the correlation between the hourly number of slams, ship speed, and fatigue damage at two structural details. It was found that the effect of the ship’s speed on the fatigue damage is not statistically significant. In addition, a sizable proportion of the fatigue damage accumulated at low to moderate ship speed, when the patrol boat experienced slamming, rather than at higher speeds. This may be due to voluntary and/or involuntary speed reduction, which is not typically taken into account in numerical fatigue analysis. That is, the use of long-term distributions of the wave environment and ship speed may mask the effects of voluntary and/or involuntary speed reduction on slamming occurrence and the fatigue damage. This finding can lead to improved requirements setting and through-life structural management of weight-optimised warships

Variabilidad en el indumento de Phaseolus vulgaris var. aborigineus (Fabaceae)

The indument of Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet, a native bean from Argentina, potential source for improvement of cultivated varieties, was compared between different genetic lines. Seeds collected from wild, weedy forms and presumptive hybrid individuals in two distant latitudes were sown in two sites of Buenos Aires University Campus (field and greenhouse). Two type of trichomes were found, which differenciate in length and shape. The pubescence density was significantly different between wild specimens from different latitudes and between culture sites for plants of a same procedence. This character could be involved in physical defences of these plants.El indumento de Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet, un poroto nativo de la Argentina, potencial fuente para mejoramiento de variedades cultivadas, se comparó entre diferentes líneas genéticas. Semillas de individuos silvestres, tipos maleza y presuntos híbridos colectadas en dos latitudes distantes fueron sembradas en dos sitios del campus de la Universidad de Buenos Aires (campo e invernáculo). Se encontraron dos tipos de tricomas que se diferencian en longitud y forma. La densidad de la pubescencia fue significativamente distinta entre especímenes silvestres de distintas latitudes y entre sitios de cultivo para plantas de la misma procedencia; este carácter podría estar relacionado con las defensas físicas de estas plantas.Fil: Ojeda, Fabiana S.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología ExperimentalFil: Amela García, María T.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología ExperimentalFil: Hoc, Patricia S.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimenta

Variabilidad en el indumento de Phaseolus vulgaris var. aborigineus (Fabaceae)

The indument of Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet, a native bean from Argentina, potential source for improvement of cultivated varieties, was compared between different genetic lines. Seeds collected from wild, weedy forms and presumptive hybrid individuals in two distant latitudes were sown in two sites of Buenos Aires University Campus (field and greenhouse). Two type of trichomes were found, which differenciate in length and shape. The pubescence density was significantly different between wild specimens from different latitudes and between culture sites for plants of a same procedence. This character could be involved in physical defences of these plants.The indument of Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet, a native bean from Argentina, potential source for improvement of cultivated varieties, was compared between different genetic lines. Seeds collected from wild, weedy forms and presumptive hybrid individuals in two distant latitudes were sown in two sites of Buenos Aires University Campus (field and greenhouse). Two type of trichomes were found, which differenciate in length and shape. The pubescence density was significantly different between wild specimens from different latitudes and between culture sites for plants of a same procedence. This character could be involved in physical defences of these plants

M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems

We have searched the Kepler light curves of ~3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, 'sonograms', and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rapid rotation from those due to stellar pulsations, eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets with rotation periods, P_rot, of < 2 days, and 110 with P_rot < 1 day. Some 30 of the 178 systems exhibit two or more independent short periods within the same Kepler photometric aperture, while several have three or more short periods. Adaptive optics imaging and modeling of the Kepler pixel response function for a subset of our sample support the conclusion that the targets with multiple periods are highly likely to be relatively young physical binary, triple, and even quadruple M star systems. We explore in detail the one object with four incommensurate periods all less than 1.2 days, and show that two of the periods arise from one of a close pair of stars, while the other two arise from the second star, which itself is probably a visual binary. If most of these M-star systems with multiple periods turn out to be bound M stars, this could prove a valuable way of discovering young hierarchical M-star systems; the same approach may also be applicable to G and K stars. The ~5% occurrence rate of rapid rotation among the ~3900 M star targets is consistent with spin evolution models that include an initial contraction phase followed by magnetic braking, wherein a typical M star can spend several hundred Myr before spinning down to periods longer than 2 days.Comment: 17 pages, 12 figures, 2 tables; accepted for publication in The Astrophysical Journa

Analytical calculation of the excess current in the OTBK theory

We present an analytical derivation of the excess current in Josephson junctions within the Octavio-Tinkham-Blonder-Klapwijk theory for both symmetric and asymmetric barrier strengths. We confirm the result found numerically by Flensberg et al. for equal barriers [Phys. Rev. B 38, 8707 (1988)], including the prediction of negative excess current for low transparencies, and we generalize it for differing barriers. Our analytical formulae provide for convenient fitting of experimental data, also in the less studied, but practically relevant case of the barrier asymmetry.Comment: 13 pages, 3 figures, submitted to Superconductor Science and Technolog

Psychometric Validation of the Information Area of Digital Competence in High School Students in Perú

Background/purpose - Few psychometric tests have been identified in the literature that analyze digital competencies in school-aged children. The Evaluation Test of Digital Competencies in Compulsory Education Students (ECODIES, Casillas-Martín et al., 2020) is considered one of the most robust for its measurement. The aim of the study was to assess the psychometric validity of the 'ECODIES - Area 1: Information' test with high school students from two Peruvian cities in 2021. Materials/methods - The research was formed as a basic level, non-experimental, and cross-sectional study. Content validity was analyzed through expert judges (n = 8), while construct validity, factorial invariance, and reliability were tested with a sample of high school students from Lima and Cusco (N = 201). Results - The content validity obtained satisfactory results (Aiken's V = 0.952, p < .01). Through construct validity, it was corroborated that the instrument measures the information competence (RMSEA = 0.052, CFI = 0.948, TLI = 0.928, PNFI = 0.67) and that this theoretical construct remains invariant between both of the groups studied. The instrument also demonstrates adequate internal consistency (α = 0.736, ω = 0.751, ordinal α = 0.869). Conclusion - 'ECODIES - Area 1: Information' is a valid and reliable instrument for the assessment of the information digital competence, including cultural differences, in high school students