Angular Momentum of the BTZ Black Hole in the Teleparallel Geometry

We carry out the Hamiltonian formulation of the three- dimensional gravitational teleparallelism without imposing the time gauge condition, by rigorously performing the Legendre transform. Definition of the gravitational angular momentum arises by suitably interpreting the integral form of the constraint equation Gama^ik=0 as an angular momentum equation. The gravitational angular momentum is evaluated for the gravitational field of a rotating BTZ black hole.Comment: 17 pages, no figures, v2: some misprints corrected, Ref.s added, Eq.s revised, submitted to General Relativity and Gravitatio

Boundary versus bulk behavior of time-dependent correlation functions in one-dimensional quantum systems

We study the influence of reflective boundaries on time-dependent responses of one-dimensional quantum fluids at zero temperature beyond the low-energy approximation. Our analysis is based on an extension of effective mobile impurity models for nonlinear Luttinger liquids to the case of open boundary conditions. For integrable models, we show that boundary autocorrelations oscillate as a function of time with the same frequency as the corresponding bulk autocorrelations. This frequency can be identified as the band edge of elementary excitations. The amplitude of the oscillations decays as a power law with distinct exponents at the boundary and in the bulk, but boundary and bulk exponents are determined by the same coupling constant in the mobile impurity model. For nonintegrable models, we argue that the power-law decay of the oscillations is generic for autocorrelations in the bulk, but turns into an exponential decay at the boundary. Moreover, there is in general a nonuniversal shift of the boundary frequency in comparison with the band edge of bulk excitations. The predictions of our effective field theory are compared with numerical results obtained by time-dependent density matrix renormalization group (tDMRG) for both integrable and nonintegrable critical spin-$S$ chains with $S=1/2$, $1$ and $3/2$.Comment: 20 pages, 12 figure

Recomendações para manejo da podrigão-do-pé em batata-doce.

bitstream/item/57209/1/Cot-79.pd

Towards robotic process automation implementation: an end-to-end perspective

Purpose: Robotic process automation (RPA) seeks to automate business processes, using software robots that interact with systems through their user interface, improving efficiency and reducing costs. However, some critical steps, such as identifying processes suitable for RPA automation, can have a tremendous impact in organizations if a wrong process is selected. Therefore, the purpose of this paper is to provide an approach for analyzing RPA development in business organizations. Design/methodology/approach: This research presents a cohesive literature review about RPA, in order to identify RPA main concepts, which should be reported and considered in all RPA case studies. A model connecting the main elicited RPA concepts is presented as well as its evaluation and applicability grounded of past RPA case study (CS) analysis, using design science research. Findings: The results from this research show that most of the RPA main concepts gathered in the literature review are not reported in the selected RPA CSs. Originality/value: As RPA is a recent topic, literature lacks a synthetization of RPA main topics. This research aims to fill the gap on that, by identifying and synthesize the main topics related to RPA and proposing a model that connects the main RPA concepts, which can be used by researchers as a schema for conducting and writing RPA case studies.info:eu-repo/semantics/acceptedVersio

Monitoramento para detecção de Ceratitis capitata (Diptera: Tephritidae) no Estado do Amapá.

bitstream/item/62612/1/AP-2012-Monitoramento-deteccao-Ceratitis-capitata.pd

Chemical abundances and kinematics of barium stars

In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, $alpha$-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code {\sc moog}. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of $alpha$-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anti-correlated with the metallicity. Our kinematical analysis showed that 90% of the barium stars belong to the thin disk population. Based on their luminosities, none of the barium stars are luminous enough to be an AGB star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.Comment: 30 pages, 26 figures, 18 tables, accepted for publication in MNRA

Can geosites be restored? The example of the Alto Vez geosite (Peneda Mountain, Portugal)

One of the most important tasks in geoheritage management is the conservation of the geosite values, protecting them from natural or human induced degradation. In some cases, degradation still occurs even with the existence of geoconservation initiatives. Normally, the loss of geodiversity features is irreversible and protection measures are only applied in order to try to stop further damage. However, should this be imperative to all types of geosites? This question emerged with the case of the restoration of the Alto Vez geosite in the Peneda Mountain, one of the most remarkable fields of glacial erratic boulders in Portugal. Besides the erratic granite boulders, other relevant glacial features occur such as an U-shaped valley and moraines, justifying the inclusion of this site as one of the most important geosites in the Portuguese geoheritage inventory. Despite its scientific relevance, it is located just outside the contiguous Peneda-Gerês National Park, the most important protected area in Portugal. This national park was founded in 1971 and its limits were defined before the scientific discovery of these relevant glacial features. In 2012, a horseracing track was constructed in the geosite by the local village administration, with the removal of erratic boulders from their original place, affecting the natural landscape and the geosite’s integrity. After a claim made by a citizen, legal and administrative actions made by the Portuguese Institute of Nature Conservation and Forests and by the municipal authorities, have resulted in the closure of the racing track, an assessment of the degradation and definition of a strategy to reduce the damages. Under our supervision, a restoration plan was conducted in 2017. Aerial photos captured by unmanned aerial vehicles were used, together with dGPS and GIS procedures. The initial topography was restored using earthmoving machinery and the buried erratic boulders were identified and carefully relocated to their original position. A management plan of the geosite is being produced in order to protect it more efficiently through a statutory designation and to promote its tourism and educational uses. This case-study shows that a well-informed society is essential to help authorities to protect geoheritage and that a geosite restoration is possible when the main geodiversity features are not yet fully destroyed