Variational Methods in AdS/CFT

We prove that the AdS/CFT calculation of 1-point functions can be drastically simplified by using variational arguments. We give a simple universal proof, valid for any theory that can be derived from a Lagrangian, that the large radius divergencies in 1-point functions can always be renormalized away (at least in the semiclassical approximation). The renormalized 1-point functions then follow by a simple variational problem involving only finite quantities. Several examples, a massive scalar, gravity, and renormalization flows, are discussed. Our results are general and can thus be used for dualities beyond AdS/CFT.Comment: 14 pages, no figures, LaTeX, minor change in footnot

Efecto del número de indicadores por factor sobre la identificación y estimación en modelos aditivos de análisis factorial confirmatorio

La matriz multirrasgo-multimétodo (MRMM) es un diseño de investigación de larga tradición en Psicología. Las técnicas de análisis de datos adecuadas para una correcta extracción de conclusiones han estado sujetas a controversia. Parece, no obstante, que diversos modelos de análisis factorial confirmatorio resultan muy adecuados. De entre los diversos modelos, dos de ellos han recibido gran atención, el modelo completo, que apareció primero en la literatura, y el de unicidades correlacionadas, que parece una alternativa razonable a los problemas que aparecen en el primero. Los resultados de ambos modelos en la literatura se refieren a situaciones con un solo indicador por combinación rasgo-método. La presente investigación simula datos de matrices MRMM para múltiples indicadores por combinación rasgo-método y somete a prueba la adecuación de las estimaciones de ambos modelos. Los resultados apuntan a un mejor comportamiento del modelo completo, si bien los sesgos, aunque triviales en cuantía, aumentan conforme aumenta la correlación entre los métodos

Differential effects of high-temperature stress on nuclear topology and transcription of repetitive noncoding and coding rye sequences

The plant stress response has been extensively characterized at the biochemical and physiological levels. However, knowledge concerning repetitive sequence genome fraction modulation during extreme temperature conditions is scarce. We studied high-temperature effects on subtelomeric repetitive sequences (pSc200) and 45S rDNA in rye seedlings submitted to 40 ° C during 4 h. Chromatin organization patterns were evaluated through fluorescent in situ hybridization and transcription levels were assessed using quantitative real-time PCR. Additionally, the nucleolar dynamics were evaluated through fibrillarin immunodetection in interphase nuclei. The results obtained clearly demonstrated that the pSc200 sequence organization is not affected by high-temperature stress (HTS) and proved for the first time that this noncoding subtelomeric sequence is stably transcribed. Conversely, it was demonstrated that HTS treatment induces marked rDNA chromatin decondensation along with nucleolar enlargement and a significant increase in ribosomal gene transcription. The role of noncoding and coding repetitive rye sequences in the plant stress response that are suggested by their clearly distinct behaviors is discussed. While the hetero-chromatic conformation of pSc200 sequences seems to be involved in the stabilization of the interphase chromatin architecture under stress conditions, the dynamic modulation of nucleolar and rDNA topology and transcription suggest their role in plant stress response pathway

Slow magnetic relaxations in a ladder-type Dy(III) complex and its dinuclear analogue

The complex {[Dy2(PDOA)3(H2O)6]·2H2O}n (1) (H2PDOA = 1, 2-phenylenedioxydiacetic acid) was prepared from aqueous solution. Its crystal structure, built up of {-Dy-O-C-O-}n chains interlinked by PDOA ligands yielding a ladder-like arrangement, was determined at 173 K. 1 exhibits slow magnetic relaxation under a small magnetic field BDC = 0.2 T with two (LF and HF) relaxation channels. The LF relaxation time at BDC = 0.2 T and T = 1.85 K is as slow as t(LF) = 46 ms whereas the HF channel is t(HF) = 1.4 ms. The mole fraction of the LF species is xLF = 0.76 at 1.85 K and it escapes progressively on heating. In the dinuclear analogue [Dy2(PDOA)3(H2O)6]·3.5H2O (2) one PDOA ligand forms a bis(chelate) bridge between the two Dy(iii) atoms yielding a local structure analogous to that in 1; however its AC susceptibility data show slightly different quantitative characteristics of the single-molecule magnetic behaviour

Avaliação do comportamento agronómico de porta-enxertos tolerantes à tristeza dos citrinos

A detecção no nosso país de alguns núcleos de plantas infectadas com o citrus tristeza virus (CTV), impôs a necessidade de desenvolver um plano de prevenção, nomeadamente através do incentivo da substituição progressiva dos porta-enxertos susceptíveis por porta-enxertos tolerantes. Com a identificação do seu principal vector (Toxoptera citricidus Kirk.) em finais 2003, nas regiões de Entre-Douro e Minho e de Trás-os-Montes é de prever que a dispersão da doença ocorra mais rapidamente. As novas plantações utilizam na sua maioria as citranjeiras Troyer e Carrizo, que nem sempre se mostram adequadas às condições edafo-climáticas existentes. Considerando esta problemática, a Direcção Regional de Agricultura do Algarve, em colaboração com outras entidades (Universidade do Algarve e Centro de Citricultura), tem vindo a desenvolver estudos conducentes à adaptação de novos porta-enxertos, com o objectivo de diversificar as opções existentes relativamente aos condicionalismos da região. Com este objectivo foi instalado em Tavira, em Maio de 1998, num solo calcário, um ensaio de campo para avaliação do comportamento de 11 clones de porta-enxertos (T. Sunki x P. trifoliata FAO 30590; Citranjeira Troyer B2 FAO 31655; T. Cleopatra x P. trifoliata FAO 30584; T. Cleopatra x C. Carrizo FAO 30575; Laranjeira Gou Tou B7; Citrandarineira 31443; Laranjeira azeda B6C-T1; Tangerineira Changsa; Tangerineira Sunki; Tangerineira Cleópatra; Citranjeira Troyer 4 AS). Durante três anos, as plantas foram submetidas a três níveis de salinidade da água de rega, expressos pela condutividade eléctrica da água de rega ECw – 1; 3 e 6 dS.m-1, obtidos através de um esquema experimental fonte dupla gota-a-gota. Foram medidos vários parâmetros agro-ambientais, como o desenvolvimento vegetativo das plantas e o aumento da condutividade eléctrica do extracto de saturação do solo (medido no extracto aquoso). Os resultados obtidos mostram que os porta-enxertos com maior tolerância à salinidade foram o clone de laranjeira azeda B6C-T1 e a laranjeira Gou Tou.info:eu-repo/semantics/publishedVersio

Social support, self-efficacy and academic satisfaction of university students during the COVID-19 lockdown

This work aimed to analyze the relationships between the students perceived institutional support, teachers’ support, peers’ support, and their academic satisfaction, mediated by their self-efficacy in information and comunication technologies (ICT). Participants were 157 students who were studying from first to fourth year in different disciplines of the Valencia University. Structural equation models with latent factors were tested. A final model had satisfactory fit indices to the observed data. It is worth highlighting the strong direct effect of the teaching staff support on student’ academic satisfaction, with less weight, although significant, being the effect of institutional support. In conclusion, teacher’s figure is of paramount importance for student’s academic satisfaction.Este trabajo tuvo como objetivo analizar las relaciones entre el apoyo institucional percibido por los estudiantes, el apoyo de los profesores, el apoyo de los compañeros y su satisfacción académica, mediada por su autoeficacia en las tecnologías de la información y la comunicación (TIC). Participaron 157 estudiantes que cursaban de primero a cuarto año en diferentes disciplinas de la Universidad de Valencia. Se probaron modelos de ecuaciones estructurales con factores latentes. El modelo final aportó índices de ajuste satisfactorios a los datos observados. Cabe destacar el fuerte efecto directo del apoyo del profesorado sobre la satisfacción académica de los estudiantes, mientras que tuvo menor peso, aunque también significativo, el efecto del apoyo institucional. En conclusión, la figura del docente es de suma importancia para la satisfacción académica de los estudiantes

THE RELATIONSHIP BETWEEN LEVEL OF EDUCATION, ORGANIZATIONAL COMMITMENT AND JOB SATISFACTION: AN ANALYSIS IN HOTEL ESTABLISHMENTS IN ANDALUSIA (SPAIN)

Nisu svi zaposlenici sposobni generirati vještine i resurse kojima bi se ostvarila organizacijska produktivnost. Samo su kvalificirani ljudski resursi (HR), prepo¬znati i odani politici tvrtke, dio organizacijskih kompetencija. Stoga su čimbenici zadovoljstva zapo¬slenika radom te predanost tvrtki dvije ključne varijable koje moramo analizirati kako bismo ispravno procijenili i pravilno upravljali ljudskim kapitalom tvrtke. Posebno se velika važnost pridaje vrijed¬nosti obrazovanja zaposlenika u svjetlu konkurentnosti turizma, što je u skladu s pretpostavkom kako stupanj obrazovanja zaposlenika izravno utječe na kvalitetu turističkih usluga. Cilj je ovog članka analizirati zadovoljstvo radnim mjestom i organizacijske obveze zaposlenika hotelskih kuća u Andaluziji (Španjolska), destinaciji čija je nesumnjiva konkurentska važnost u turi¬zmu neupitna. Pronađene su evidentne razlike u stupnju obrazovanja zaposlenika, tako da rezultati svakako ohrabruju odjele upravljanja ljudskim resursima na identifikaciju, održavanje i razvoj resursa i potencijalnih sposobnosti njihovog ljudskog kapitala.Not all employees are capable of generating skills and resources that may result in organizational productivity. Only qualified Human Resources, identified and committed to the company policy, are a part of the organization\u27s competences. Therefore, elements like the worker\u27s job satisfaction or the organizational commitment are two fundamental variables that need to be analyzed for the measurement and correct management of the company\u27s human capital. Further¬more, the importance that the value of the workers\u27 education presents towards competitiveness in tourism is highlighted since it is assumed that staff education is directly related to the quality of tourist service. The purpose of this paper is to analyze the relationship among educational level, job satisfaction, and organizational commitment of the employees of the hotel establishments in Andalusia (Spain), a destination of undeniable competitive significance in tourism. Evident differences were found among the level of education of workers, so the results have to encourage the human resources management to identify, maintain, and develop the resources and potential capabilities of their human capital

Measuring School Engagement: Validation and Measurement Equivalence of the Student Engagement Scale on Angolan Male and Female Adolescents

School engagement is defined primarily in relation to the participation of the student in academic achievement, and it is viewed as a multidimensional and integrative construct, or macroconstruct made up of several dimensions. The most repeated typology recognizes three specific dimensions: Cognitive, behavioral, and emotional (affective). Recently, a fourth new dimension, personal agency, has been proposed, which reflects students’ constructive engagement with the academic instructions. F. Veiga has been the first to present a self-report instrument, in Portuguese, to measure these four components, the Student Engagement Scale-4 dimensions (SES-4DS). This research has studied the validity and reliability of this scale and its gender invariance in a sample of 2034 Angolan students. Results have shown a clear scalar invariant factor structure, some reliability problems, and adequate convergent and nomological validity. Latent differences were found between males and females for cognitive and affective engagement. Results are discussed in light of the existing literature

Si/SiC bonded wafer: a route to carbon free SiO2 on SiC

This paper describes the thermal oxidation of Si/SiC heterojunction structures, produced using a layer-transfer process, as an alternative solution to fabricating SiC metal-oxide-semiconductor (MOS) devices with lower interface state densities (Dit). Physical characterization demonstrate that the transferred Si layer is relatively smooth, uniform, and essentially monocrystalline. The Si on SiC has been totally or partially thermally oxidized at 900–1150 °C. Dit for both partially and completely oxidized silicon layers on SiC were significantly lower than Dit values for MOS capacitors fabricated via conventional thermal oxidation of SiC. The quality of the SiO2, formed by oxidation of a wafer-bonded silicon layer reported here has the potential to realize a number of innovative heterojunction concepts and devices, including the fabrication of high quality and reliable SiO2 gate oxides

La reconstrucción de la lección : un estímulo para el aprendizaje de las ciencias en Educación Básica

The research reported below is an attempt to measure the value of "lesson reconstruction" as a didactic stimulus. More than one hundred students, belonging to three classes of the seventh year of Basic Education, participated in this study. The subject matter was Natural Sciences and, more specifically, Physics. The treatments of the two experimental groups were two different types of "lesson reconstruction", one of them based on the questioning by the teacher, and the other based on questionnaires applied to small groups of students. The third group of students was the control group. The results, reported for individuals and groups, show that these treatments can be effective after an accommodation period, more significantly in the treatment based on questionnaires