208 research outputs found
From The Big Apple To Big Ben: An Insight Into Menu Labeling
Imagine looking around and recognizing that you are much heavier than your fellow peers
Secular changes in length of day: Effect of the mass redistribution
In this paper the secular change in the length of day due to mass redistribution effects is revisited using the Hamiltonian formalism of the Earth rotation theories. The framework is a two-layer deformable Earth model including dissipative effects at the core–mantle boundary, which are described through a coupling torque formulated by means of generalized forces. The theoretical development leads to the introduction of an effective time-averaged polar inertia moment, which allows us to quantify the level of core–mantle coupling throughout the secular evolution of the Earth. Taking advantage of the canonical procedure, we obtain a closed analytical formula for the secular deceleration of the rotation rate, numerical evaluation of which is performed using frequency-dependent Love numbers corresponding to solid and oceanic tides. With this Earth modeling, under the widespread assumption of totally coupled core and mantle layers in the long term response, a secular angular acceleration of − 1328.6′′ cy−2 is obtained, which is equivalent to an increase of 2.418 ms cy−1 in the length of day. The ocean tides and the semidiurnal band of the mass-redistribution-perturbing potential, mostly induced by the Moon, constitute the main part of this deceleration. This estimate is shown to be in very good agreement with recent observational values, and with other theoretical predictions including comparable modeling features
Dynamical adjustments in IAU 2000A nutation series arising from IAU 2006 precession
The adoption of International Astronomical Union (IAU) 2006 precession model, IAU 2006 precession, requires IAU 2000A nutation to be adjusted to ensure compatibility between both theories. This consists of adding small terms to some nutation amplitudes relevant at the microarcsecond level. Those contributions were derived in previously published articles and are incorporated into current astronomical standards. They are due to the estimation process of nutation amplitudes by Very Long Baseline Interferometry (VLBI) and to the changes induced by the J2 rate present in the precession theory. We focus on the second kind of those adjustments, and develop a simple model of the Earth nutation capable of determining all the changes arising in the theoretical construction of the nutation series in a dynamical consistent way. This entails the consideration of three main classes of effects: the J2 rate, the orbital coefficients rate, and the variations induced by the update of some IAU 2006 precession quantities. With this aim, we construct a first order model for the nutations of the angular momentum axis of the non-rigid Earth. Our treatment is based on a Hamiltonian formalism and leads to analytical formulae for the nutation amplitudes in the form of in-phase, out-of-phase, and mixed secular terms. They allow numerical evaluation of the contributions of the former effects. We conclude that the accepted corrections associated with the J2 rate must be supplemented with new, hitherto unconsidered terms of the same order of magnitude, and that these should be incorporated into present standards
Promoting energy efficiency at household level: a literature review
The household sector is one of the most energy-intensive sectors in Europe, and thus a focal point for reducing greenhouse gas emissions associated with energy consumption. Energy efficiency is considered a key measure to reduce household energy consumption, but several factors could lead to an underinvestment in energy efficiency. This is the so-called energy efficiency gap or paradox. The factors in question are grouped under market failures (including informational failures), behavioural failures and other factors. Various policies can be used to address these failures and promote the adoption of energy-efficient technologies, including energy standards and codes, economic incentives and information instruments. This paper reviews the empirical evidence to date on energy efficiency policies and discusses their effectiveness. On the one hand, command and control instruments seem to be effective policies, but they have to overcome several barriers. In the case of price instruments, subsidies and taxes do not seem to be effective while rebates present mixed results as they sometimes are effective and in other cases, they could present significant shortcomings. Finally, the effectiveness of informational policies is not always ensured as they depend on the country, sector and product category. Information feedback tools also seem to be effective as they work as a constant reminder of energy-efficient behaviour. Some limitations of energy efficiency policies are also identified, such as the difficulties of implementing codes and standards given that a minimum level need to be achieved, differences in the effectiveness of rebate programmes and non-conclusive results in regard to the effectiveness of monetary energy efficiency labels. © 2020, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.This study was conducted as part of the CONSumer Energy Efficiency Decision making (CONSEED) project, an EU-funded H2020 research project under grant agreement number 723741. This research is also supported by the Spanish State Research Agency through MarÃa de Maeztu Excellence Unit accreditation 2018-2022 (Ref. MDM-2017-0714). The project leading to these results has received funding from ‘la Caixa’ Foundation under the project SR0435 led by Ibon Galarraga. Amaya de Ayala also acknowledges the support of Fundación Ramon Areces under XVIII Concurso Nacional para la Adjudicación de Ayudas a la Investigación en Ciencias Sociales. Marta Escapa is grateful for financial support from the University of the Basque Country (Grant GIU18/136) and from the Spanish Ministry of Science, Innovation and Universities (Grant RTI2018-093352-B-I00)
Earth’s Rotation: A Challenging Problem in Mathematics and Physics
A suitable knowledge of the orientation and motion of the Earth in space is a common need in various fields. That knowledge has been ever necessary to carry out astronomical observations, but with the advent of the space age, it became essential for making observations of satellites and predicting and determining their orbits, and for observing the Earth from space as well. Given the relevant role it plays in Space Geodesy, Earth rotation is considered as one of the three pillars of Geodesy, the other two being geometry and gravity. Besides, research on Earth rotation has fostered advances in many fields, such as Mathematics, Astronomy and Geophysics, for centuries. One remarkable feature of the problem is in the extreme requirements of accuracy that must be fulfilled in the near future, about a millimetre on the tangent plane to the planet surface, roughly speaking. That challenges all of the theories that have been devised and used to-date; the paper makes a short review of some of the most relevant methods, which can be envisaged as milestones in Earth rotation research, emphasizing the Hamiltonian approach developed by the authors. Some contemporary problems are presented, as well as the main lines of future research prospected by the International Astronomical Union/International Association of Geodesy Joint Working Group on Theory of Earth Rotation, created in 2013.This work has been partially supported by the Spanish government under Grants AYA2010-22039-C02-01 and AYA2010-22039-C02-02 from Ministerio de EconomÃa y Competitividad (MINECO), the University of Alicante under Grant GRE11-08 and the Generalitat Valenciana, Grant GV/2014/072
The theory of canonical perturbations applied to attitude dynamics and to the Earth rotation. Osculating and nonosculating Andoyer variables
The Hamiltonian theory of Earth rotation, known as the Kinoshita-Souchay
theory, operates with nonosculating Andoyer elements. This situation parallels
a similar phenomenon that often happens (but seldom gets noticed) in orbital
dynamics, when the standard Lagrange-type or Delaunay-type planetary equations
unexpectedly render nonosculating orbital elements. In orbital mechanics,
osculation loss happens when a velocity-dependent perturbation is plugged into
the standard planetary equations. In attitude mechanics, osculation is lost
when an angular-velocity-dependent disturbance is plugged in the standard
dynamical equations for the Andoyer elements. We encounter exactly this
situation in the theory of Earth rotation, because this theory contains an
angular-velocity-dependent perturbation (the switch from an inertial frame to
that associated with the precessing ecliptic of date).
While the osculation loss does not influence the predictions for the figure
axis of the planet, it considerably alters the predictions for the
instantaneous spin-axis' orientation. We explore this issue in great detail
Graphene oxide electrodeposited electrode enhances start-up and selective enrichment of exoelectrogens in bioelectrochemical systems
15 p.This study seeks to assess the impact that the anodic electrodeposition of graphene oxide (GO) has
on the start-up process and on the development of microbial communities on the anode of BESs.
The GO electrodeposited electrodes were characterised in abiotic conditions to verify the extent of
the modifcation and were then transferred to a bioelectrochemical reactor. Results showed that
the modifed electrode allowed for a reduced start-up time compared to the control electrode. After
three months, high throughput sequencing was performed, revealing that electrochemically reduced
graphene oxide acts as a selective agent toward exoelectrogenic bacteria as Geobacter. Overall, this
study shows that GO modifed electrodes enhance bioflm build up in BES. This research was possible thanks to the financial support of the ‘Ministerio de EconomÃa y Competitividad’ project ref: CTQ2015-68925-R, cofinanced by FEDER funds. Ana Sotres thanks the regional ‘Junta de Castilla y León’ for the postdoctoral contract associated with project ref: LE060U16, cofinanced by FEDER fundsS
A First Assessment of the Corrections for the Consistency of the IAU2000 and IAU2006 Precession-Nutation Models
The Earth precession-nutation model endorsed by resolutions of each the International Astronomical Union and the International Union of Geodesy and Geophysics is composed of two theories developed independently, namely IAU2006 precession and IAU2000A nutation. The IAU2006 precession was adopted to supersede the precession part of the IAU 2000A precession-nutation model and tried to get the new precession theory dynamically consistent with the IAU2000A nutation. However, full consistency was not reached, and slight adjustments of the IAU2000A nutation amplitudes at the micro arcsecond level were required to ensure consistency. The first set of formulae for these corrections derived by Capitaine et al. (Astrophys 432(1):355–367, 2005), which was not included in IAU2006 but provided in some standards and software for computing nutations. Later, Escapa et al. showed that a few additional terms of the same order of magnitude have to be added to the 2005 expressions to get complete dynamical consistency between the official precession and nutation models. In 2018 Escapa and Capitaine made a joint review of the problem and proposed three alternative ways of nutation model and its parameters to achieve consistency to certain different extents, although no estimation of their respective effects could be worked out to illustrate the proposals. Here we present some preliminary results on the assessment of the effects of each of the three sets of corrections suggested by Escapa and Capitaine (Proceedings of the Journées, des Systémes de Référence et de la Rotation Terrestre: Furthering our Knowledge of Earth Rotation, Alicante, 2018) by testing them in conjunction with the conventional celestial pole offsets given in the IERS EOP14C04 time series.The four first authors were partially supported by Spanish Project AYA2016-79775-P (AEI/FEDER, UE)
Integrative paleobotany: Affirming the role of fossils in modern plant biology - Introduction and dedication
If you are interested in plant evolution, try this quick exercise: take a phylogenetic tree of the plant kingdom, close your eyes, and point your finger randomly to a node of the phylogeny. Irrespective of the clade to which you are pointing, there is one thing you should know about it: the living representatives of that clade have evolved as a result of a long process in which failed attempts are the rule, and as a result, the diversity of extinct forms accumulated in the fossil record far exceeds that recorded in the extant flora. From this simple concept, Gar W. Rothwell made his career. Because of that, here is a second thing you should know about the plant clade to which you pointed at random: Gar has, more likely than not, contributed information about evolution in that clade at some point in his career. Gar was one of the principal contributors to the revival of paleobotany from a largely descriptive discipline to a vibrant field of investigation at the forefront of modern evolutionary sciences that contributes crucial insights into plant evolution, equal in importance to those provided by genetics and molecular biology. Because of this, the impact of Gar’s scientific contributions reaches far beyond the field of paleobotany, with important implications for wide areas of plant biology, including anatomy and morphology, development, systematics, phylogeny, and evolution. Gar earned a master’s degree in the laboratory of Thomas N. Taylor (University of Illinois at Chicago, 1966) studying Paleozoic seeds in the genus Conostoma (Rothwell and Eggert 1970; Rothwell 1971a). He subsequently earned his PhD degree in the laboratory of Wilson N. Stewart (University of Alberta, 1973), where he reconstructed the plants in the seed fern genus Callistophyton (Rothwell 1972b, 1975, 1980, 1981). His work was instrumental in ushering in studies of fossil plants as whole living organisms, looking at both structure and development. These early experiences launched Gar on a career in plant evolutionary biology that stretched over a half century, during which he occupied positions at the University of Alberta, University of London–Chelsea College, Ohio University, and Oregon State University. Throughout his career, Gar’s scholarly work and contributions have been recognized by numerous awards and honors: the Isabel Cookson Award, the Edgar T. Wherry Award, the Michael A. Cichan Award, the Merit Award of the Botanical Society of America, and honorary membership in the International Organization of Palaeobotany, where he served for 12 years as secretary-treasurer and president.Fil: Escapa, Ignacio Hernán. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Tomescu, Alexandru M. F.. Humboldt State University. Department of Biological Sciences; Estados UnidosFil: Dunn, Michael T.. Cameron University. Department of Agriculture, Biology and Health Science; Estados UnidosFil: Stockey, Ruth A.. State University of Oregon; Estados Unido
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