Generalized commutation relations and Non linear momenta theories, a close relationship

A revision of generalized commutation relations is performed, besides a description of Non linear momenta realization included in some DSR theories. It is shown that these propositions are closely related, specially we focus on Magueijo Smolin momenta and Kempf et al. and L.N. Chang generalized commutators. Due to this, a new algebra arises with its own features that is also analyzed.Comment: accepted version in IJMP

The Introduction of DTT in Latin America: Politics and Policies

The switch to digital terrestrial television is now a global trend. In Latin America, where the terrestrial platform has a dominant role, the introduction of DTT raises important questions for economic and industrial development, as well as pluralism. This article focuses on the earliest experiences (Brazil, México and Argentina) and those of the newcomers (Chile, Colombia and Uruguay). The aim is to outline the differences between the various political decision processes and the way with which they have been turned into communication policies, so as to draw some conclusions that contribute to visualizing the future of television in the region.Publicad

A Monte Carlo model for the simulation of the electrodeposition of CoNi alloys onto glassy carbon

In this work, a Monte Carlo method for the simulation of the early stages of CoNi electrodeposition is presented. The model was constructed based on previous experimental parameters obtained with Co, Ni and CoNi electrodeposition onto a glassy carbon electrode. The core of the proposed simulation model consists of two Monte Carlo modules. The first one is a lattice grand-canonical Monte Carlo module which intends to calculate the energies of all possible events associated with metal deposition, namely adsorption, desorption and surface diffusion. The second one is a Kinetic Monte Carlo module which associates the previously calculated energies with reaction rates and probabilities of occurrence of the events, being analogous to the temporal evolution of the metallic electrodeposition.Fil: Frank, André C.. Universidade de Sao Paulo; BrasilFil: Sumodjo, Paulo T.. Universidade de Sao Paulo; BrasilFil: Leiva, Ezequiel Pedro M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Self-consistency in Theories with a Minimal Length

The aim of this paper is to clarify the relation between three different approaches of theories with a minimal length scale: A modification of the Lorentz-group in the 'Deformed Special Relativity', theories with a 'Generalized Uncertainty Principle' and those with 'Modified Dispersion Relations'. It is shown that the first two are equivalent, how they can be translated into each other, and how the third can be obtained from them. An adequate theory with a minimal length scale requires all three features to be present.Comment: typos corrected, published with new title following referee's advic

Tree—Open Grassland Structure and Composition Drive Greenhouse Gas Exchange in Holm Oak Meadows of the Iberian Peninsula

Iberian holm oak meadows are savannah-like ecosystems that result from traditional silvo-pastoral practices. However, such traditional uses are declining, driving changes in the typical tree—open grassland structure of these systems. Yet, there are no studies integrating the whole ecosystem—including the arboreal and the herbaceous layer—as drivers of greenhouse gas (GHG: CO2, CH4 and N2O) dynamics. Here, we aimed at integrating the influence of tree canopies and interactions among plant functional types (PFT: grasses, forbs, and legumes) of the herbaceous layer as GHG exchange drivers. For that purpose, we performed chamber-based GHG surveys in plots dominated by representative canopy types of Iberian holm oak meadows, including Quercus species and Pinus pinea stands, the last a common tree plantation replacing traditional stands, and unraveled GHG drivers through a diversity-interaction model approach. Our results show the tree–open grassland structure, especially drove CO2 and N2O fluxes, with higher emissions under the canopy than in the open grassland. Emissions under P. pinea canopies are higher than those under Quercus species. In addition, the inclusion of diversity and compositional terms of the herbaceous layer improve the explained variability, with legumes enhancing CO2 uptake and N2O emissions. Changes in the tree cover and tree species composition, in combination with changes in the structure and composition of the herbaceous layer, will imply deep changes in the GHG exchange of Iberian holm oak meadows. These results may provide some guidelines to perform better management strategies of this vast but vulnerable ecosystem.This work was funded by the Spanish Science Foundation FECYT-MINECO: BIOGEI (GL2013-49142-C2-1-R) and IMAGINE (CGL2017-85490-R) projects and supported by a FPI fellowship to Mercedes Ibañez (BES-2014-069243)

Recent Advances in Complex Fluids Modeling

In this chapter, we present a brief description of existing viscoelastic models, starting with the classical differential and integral models, and then focusing our attention on new models that take advantage of the enhanced properties of the Mittag-Leffler function (a generalization of the exponential function). The generalized models considered in this work are the fractional Kaye-Bernstein, Kearsley, Zapas (K-BKZ) integral model and the differential generalized exponential Phan-Thien and Tanner (PTT) model recently proposed by our research group. The integral model makes use of the relaxation function obtained from a step-strain applied to the fractional Maxwell model, and the differential model generalizes the familiar exponential Phan-Thien and Tanner constitutive equation by substituting the exponential function of the trace of the stress tensor by the Mittag-Leffler function. Since the differential model is based on local operators, it reduces the computational time needed to predict the flow behavior, and, it also allows a simpler description of complex fluids. Therefore, we explore the rheometric properties of this model and its ability (or limitations) in describing complex flows

Smart meter security: Vulnerabilities, threat impacts, and countermeasures

© Springer Nature Switzerland AG 2019. Advanced Metering Infrastructure (AMI) is the aggregation of smart meters, communications networks, and data management systems that are tailored to meet the efficient integration of renewable energy resources. The more complex features and soundless functionalities the AMI is enhanced with, the more cyber security concerns are raised and must be taken into consideration. It is imperative to assure consumer’s privacy and security to guarantee the proliferation of rolling out smart metering infrastructure. This research paper analyzes AMI from security perspectives; it discusses the possible vulnerabilities associated with different attack surfaces in the smart meter, their security and threat implications, and finally it recommends proper security controls and countermeasures. The research findings draw the foundation upon which robust security by design approach is geared for the deployment of the AMI in the future

Young Hispanics’ Motivations to Use Smartphones: A Three-Country Comparative Study

The fast-changing digital media environment has provoked new communication processes in contemporary society. In particular, younger generations engage in new ways of interacting with each other thanks to the constant emergence of digital technologies and mobile communication outlets. New habits arise every year, changing not only our interpersonal communication, but also our overall consumption of information and entertainment content, with video and instant messaging apps being particularly popular among younger populations. This study employs a mixed method approach to measure young Hispanics’ motivations to use smartphones in Chile, Mexico and the U.S. The subjects, 18 to 25 years old, participated in focus groups and surveys conducted in 2015: 55 Hispanic smartphone users joined focus groups whilst 1,403 respondents completed surveys in Chile, Mexico and Texas (U.S.). Results show similarities and differences in young Hispanics’ motivations and uses of smartphones, including the personal and commercial value they ascribe to information, time spent on social networks, and their preferences for mobile devices compared to other media. The findings are used to develop three archetypes of young users, based on smartphone’s motivations and uses. Utilizing factor analysis scores, a linear regression analysis was conducted to identify the main traits of these three archetypes: “always connected,” “entertained,” and “secure.

Capturing of organic carbon and nitrogen in eelgrass sediments of southern Scandinavia

The ability of seagrass meadows to filter nutrients and capture and store CO2 and nutrients in the form of organic carbon (OC) and nitrogen (N) in their sediments may help to mitigate local eutrophication as well as climate change via meadow restoration and protection. This study assesses OC and N sediment stocks (top 50 cm) and sequestration rates within Danish eelgrass meadows. At four locations, eelgrass-vegetated and nearby unvegetated plots were studied in protected and exposed areas. The average OC and N sediment 50 cm stocks were 2.6 ± 0.3 kg OC m − 2 and 0.23 ± 0.01 kg N m − 2, including vegetated and unvegetated plots. In general, OC and N stocks did not differ significantly between eelgrass meadows and unvegetated sediments. Lack of accumulation of excess 210Pb suggested sediment erosion or low rates of sediment accumulation at most sites. OC accumulation rates ranged from 6 to 134 g m − 2 yr − 1 and N from 0.7 to 14 g m − 2 yr − 1. Generalized additive models showed that ≥ 80 % of the variation in sediment OC and N stocks was explained by sediment grain size, organic matter source, and hydrodynamic exposure. Long cores, dated with 210Pb, showed declining OC and N densities toward present time, suggesting long-term declines in eelgrass OC and N pools. Estimates of potential nation-wide OC and N accumulation in eelgrass sediments show that they could annually capture up to 0.7 % ± 0.5 % of CO2 emissions and 6.9 % ± 5.2 % of the total terrestrial N load

Region-specific drivers cause low organic carbon stocks and sequestration rates in the saltmarsh soils of southern Scandinavia

Saltmarshes are known for their ability to act as effective sinks of organic carbon (OC) and their protection and restoration could potentially slow down the pace of global warming. However, regional estimates of saltmarsh OC storage are often missing, including for the Nordic region. To address this knowledge gap, we assessed OC storage and accumulation rates in 17 saltmarshes distributed along the Danish coasts and investigated the main drivers of soil OC storage. Danish saltmarshes store a median of 10 kg OC m−2 (interquartile range, IQR: 13.5–7.6) in the top meter and sequester 31.5 g OC m−2 yr−1 (IQR: 41.6–15.7). In a global context, these values are comparatively low. Soils with abundant clay (&gt; 20%), older and stable saltmarshes in mesohaline settings, and with low proportion of algal organic material showed higher OC densities, stocks, and accumulation rates. Grazing led to significantly higher OC stocks than neighboring ungrazed locations, likely due to trampling modifying soil abiotic conditions (higher erosion-resistance and higher clay content) that slow carbon decay. Scaling up, Danish saltmarsh soils, comprising about 1% of the country's area, have the potential to yearly capture up to 0.1% of Denmark's annual consumption-based CO2 emissions. Our research expands the baseline data needed to advance blue carbon research and management in the Nordic region while highlighting the need for a more comprehensive approach to saltmarsh management that considers the full range of services of these ecosystems and does not only focus on climate benefits.</p