Self-similar transmission properties of aperiodic Cantor potentials in gapped graphene

We investigate the transmission properties of quasiperiodic or aperiodic structures based on graphene arranged according to the Cantor sequence. In particular, we have found self-similar behaviour in the transmission spectra, and most importantly, we have calculated the scalability of the spectra. To do this, we implement and propose scaling rules for each one of the fundamental parameters: generation number, height of the barriers and length of the system. With this in mind we have been able to reproduce the reference transmission spectrum, applying the appropriate scaling rule, by means of the scaled transmission spectrum. These scaling rules are valid for both normal and oblique incidence, and as far as we can see the basic ingredients to obtain self-similar characteristics are: relativistic Dirac electrons, a self-similar structure and the non-conservation of the pseudo-spin. This constitutes a reduction of the number of conditions needed to observe self-similarity in graphene-based structures, see D\'iaz-Guerrero et al. [D. S. D\'iaz-Guerrero, L. M. Gaggero-Sager, I. Rodr\'iguez-Vargas, and G. G. Naumis, arXiv:1503.03412v1, 2015]

Propiedades de transmisión de electrones de Dirac a través de superredes Cantor en grafenoTransmission properties of Dirac electrons through Cantor monolayer graphene superlattices

In this work we use the transfer matrix method to studythe tunneling of Dirac electrons through aperiodic monolayer graphene superlattices. We consider a graphene sheet deposited on top of slabs of Silicon-Oxide (SiO2) and Silicon-Carbide (SiC) substrates, in which we applied the Cantor’s series. We calculatethe transmittance for different fundamental parameters such as: starting width, incident energy, incident angle and generation number of the Cantor’s series. In this case, the transmittance as function of energy presents self-similar features as a function of the generation number. We also compute the angular distribution of the transmittance for fixed energies finding a self-similar patterns between generations. Finally, we calculate the scaling factor for some transmittance spectra, which effectively show scalability.En este trabajo usamos el método de la matriz de transferencia para estudiar el tunelamiento de los electrones de Dirac a través de superredes aperiodicas en grafeno. Consideramosuna hoja de grafeno depositada encima de bloques de sustratos de Óxido de Silicio (SiO2) y Carburo de Silicio (SiC), en los cuales aplicamos la serie de Cantor. Calculamos la transmitancia para diferentes parámetros fundamentales tales como: ancho de partida, energía de incidencia, ángulo de incidencia y número de generación de la serie de Cantor. En este caso, la transmitancia como función de la energía presenta rasgos autosimilares al variar el número de generación. También computamos la distribución angular de la transmitancia para energías fijas econtrando un patrón autosimilar entre generaciones. Por último, calculamos los factores de escala para algunos espectros de la transmitancia, los cuales efectivamente muestran escalabilida

Inter-rater and intra-rater reliability of the extended TUG test in elderly participants

Background: To analyse the reliability, variance and execution time of the Extended Timed Up and Go (Extended TUG) test in three age groups of elderly participants (G1: 55–64 years; G2: 65–74 years; G3: 75–85 years). Methods: An analytical cross-sectional study of 114 recruited participants (63 women) of average age 70.17 (± 7.3) years was undertaken. Each participant performed the Extended TUG three consecutive times, with a rest break between tests of 120 s. Both the intragroup and intergroup reliability of the measurements in the Extended TUG were analysed. Results: The reliability of the Extended TUG test is excellent for the first and second decades but drops down to good for the third decade. Specifically, intragroup reliability ranged from 0.784 for G3 to 0.977 for G1 (G2 = 0.858). Intergroup reliability, compared with intragroup reliability, was slightly lower, ranging between 0.779 for G3 and 0.972 for G1 (G2 = 0.853). Conclusion: The reliability of the Extended TUG test progressively decreases with increasing age, being excellent for the younger age groups and good for the oldest age group

Compuestos químicos inductores de resistencia contra Colletotrichum gloeosporioides en mangó

Various resistance-inducing chemicals were assessed in the interaction between mango (Mangifera indica L.) and the anthracnose pathogen Colletotrichum gloeosporioides. These were salicylic acid, isonicotinic acid, benzo (1,2,3) thiadiazole-7-carbothionic acid S-methyl ester (Actigard®)7, and other chemical compounds structurally similar, such as nicotinic acid, nicotinic acid adenine dinucleotide, isonicotinic acid ethyl ester, N-oxide isonicotinic acid, benzoic acid and sodium benzoate. No significant differences (P > 0.05) in C. gloeosporioidescolony growth were detected on culture media amended with the different resistance-inducing chemicals evaluated. At laboratory conditions, these compounds were sprayed to runoff on mango leaves and fruit pieces prior to inoculation. Lesion size was significantly reduced (P > 0.10) by concentrations ranging from 10-12 M to 10-6 M of salicylic acid (SA), 10-18 M and 10-14 M of isonicotinic acid (INA), 10-17 M to 10-2 M of Actigard®, and 10-10 M benzoic acid (BA). Salicylic acid, INA and BA caused toxicity on leaves at concentrations ranging from 10-1 to 10-3 M. Chemical compounds that induced resistance at laboratory conditions were further evaluated on six-month-old mango seedlings in a shade house. None of the chemicals tested significantly (P > 0.05) reduced lesion size caused by C. gloeosporioides. Other resistance-inducing chemicals not tested during these studies, such as probenazole, cyclopropane carboxylic acid derivatives, non-protein amino acids [β-aminobutyric acid (BABA) and  ϒ-aminobutyric acid (GABA)] and Phytoguard®, should be evaluated individually and in combinations to clarify this lack of induced resistance in mango tissues. Se evaluaron varios compuestos químicos inductores de resistencia en la interacción entre mangó (Mangifera indica L.) y el patógeno, agente causal de la antracnosis, Colletotrichum gloeosporioides. Los compuestos evaluados fueron ácido salicílico, ácido isonicotínico, ácido benzo (1,2,3) tiadiazol-7-carbotiónico áster de S-metilo (Actigard®) y otros compuestos químicos estructuralmente similares como el ácido nicotínico, el dinucleótido de adenina de ácido nicotínico, el áster de etilo del ácido isonicotínico, el N-óxido de ácido isonicotínico, el ácido benzoico y el benzoato de sodio. En el laboratorio antes de la inoculación, estos compuestos se asperjaron hasta la saturación sobre pedazos de hojas y frutas de mangó. En condiciones de laboratorio, el tamaño de las lesiones causadas por C. gloeosporioidesen pedazos de hojas y frutas de mangó se redujo significativamente (P < 0.10) a concentraciones que fluctuaron entre 10-12 M a 10-6 M de ácido salicílico (SA), 10-18 M y 10-14 M de ácido isonicotínico (INA), 10-17 M a 10-2 M de Actigard® y 10-10 M de ácido benzoico (BA). El ácido salicílico, INA y BA causaron toxicidad en las hojas a concentraciones que fluctuaron entre 10-1 a 10-3 M.  Los compuestos químicos que indujeron resistencia en condiciones de laboratorio se evaluaron en árboles de mangó de seis meses de edad en condiciones de umbráculo. Ninguno de los compuestos químicos evaluados redujo significativamente (P < 0.05) el tamaño de la lesión causada por C. gloeosporioides. Otros agentes químicos inductores de resistencia que no fueron evaluados durante estos estudios, tales como probenazol, derivados ciclopropanos de ácido carboxílico, aminoácidos no-proteícos [β-ácido aminobutírico (BABA) y ϒ-ácido aminobutírico (GABA)] y Phytogard®, se deben evaluar individualmente y en combinación para clarificar la ausencia de inducción de resistencia en los tejidos del mangó

La familia a la luz del carácter personal

En este artículo queremos abordar la familia desde la intimidad personal, ver sus manifestaciones y entresacar aquellos rasgos comunitarios que la caracterizan, así como las virtudes que fomentan esos rasgos comunitarios. Comenzaremos por exponer, brevemente, la propuesta que sobre los trascendentales personales hace Leonardo Polo, con la finalidad de entender que es la intimidad personal. A continuación veremos la manifestación de la familia desde cada uno de esos trascendentales. Finalmente, entresacamos de los trascendentales personales los rasgos comunitarios que caracterizan a la familia. Esto nos permitirá considerar una definición de familia anclada en la intimidad personal, así como la distinción que puede hacerse entre familia e Institución familiar, bien sea si hablamos de la intimidad personal o del ámbito manifestativo de esa intimidad. Comenzaremos con una breve descripción de esos trascendentales y, posteriormente, desde un carácter sistémico abordaremos los rasgos comunitarios que caracterizan a la Institución familiar

Interference with polarized light beams: Generation of spatially varying polarization

Using a scheme based on a Mach-Zehnder interferometer, we propose an analysis of the superposition of polarized laser beams at a given angle. The focus of our study is the spatially varying polarization state of the resulting field, also known as a polarization grating, generated by this setup. Our proposal combines a theoretical description of the resulting field in terms of its Stokes parameters with an experimental demonstration of the existence of such a polarization grating due to the effects of polarization on beam interference experiments.Comment: 16 pages, 9 figure

Alzheimer\u27s Disease: From Animal Models to the Human Syndrome

Some animal models, genetically modified (such as murine) and sporadic (as others species), enable the study of the origin of specific lesions observed in human neurodegenerative diseases. In particular, Alzheimer\u27s disease (AD) models have been designed to test the hypothesis that certain lesions are associated with functional and morphological changes beginning with memory loss and impairment in activities of daily life. This review compares and evaluates the phenotypes of different AD animal models, on the basis of the specific objectives of each study, with the purpose of encompassing their contributions to the comprehension of the AD signs and symptoms in humans. All these models contribute to the comprehension of the human AD mechanisms regarding the heterogeneity of AD phenotypes: the overlap between AD and age‐related changes, the variability of AD onset (early or late), the probable reactiveness of amyloid‐β and tau proteins, the scarcity of senile plaques and/or neurofibrillary tangles in some AD cases, the spatial correlation of the pathology and cerebral blood vessels, and the immunological responses (microglial aging) and synaptopathy. Altogether, these considerations may contribute to find therapies to treat and prevent this disease

La invocabilidad de la acción de cumplimiento frente a los compromisos suscritos en el paro nacional Agrario de 2013: Un análisis desde la regulación de las semillas certificadas en Colombia

Este artículo analiza el rol de la acción de cumplimiento tras el escenario que supuso el incumplimiento del Gobierno sobre lo pactado en los acuerdos regionales que motivaron la terminación del Paro Nacional Agrario de 2013, mediante los cuales se suscribió el compromiso de suspender mecanismos policivos de decomiso y destrucción de semillas no certificadas, así como de mejorar condiciones para continuar con las prácticas tradicionales de resiembra que a los campesinos les ha garantizado su soberanía alimentaria durante generaciones. El problema jurídico que se busca abordar es de si tal incumplimiento se generó o no en un contexto de inseguridad jurídica para las comunidades campesinas, en su condición de administrados y, si en tal sentido, se presentó una defraudación de su confianza legítima. Se propone que, a través de la legítima confianza y la buena fe como enfoques interpretativos, la acción de cumplimiento sería invocable en esta situación particular. © 2018, Universidad de Caldas.The article analyzes the role of the compliance action after the scenario supposing the failure of the Government to comply with the regional agreements that led to the termination of the National Agrarian Strike in 2013 through which commitment to suspend police confiscation mechanisms and destruction of non-certified seeds, as well as to improve conditions to continue with the traditional practices of replanting, which have guaranteed peasants their food sovereignty for generations, was signed. The legal problem to be addressed is whether the non-compliance was generated in a context of legal uncertainty for the peasant communities in their condition of being administered and, in that sense, if defrauding of their legitimate expectations was present. It is proposed that, through legitimate trust and good faith as interpretive approaches, enforcement action would be invoked in this situation. © 2018, Universidad de Caldas