4,954 research outputs found
On the effective action of the vacuum photon splitting in Lorentz-violating QED
We consider one-loop radiative corrections from Lorentz- and CPT- violating
extended QED to address the specific problem of finding explicitly an effective
action describing amplitude of photon triple splitting. We show that it is not
possible to find a nonzero photon triple splitting effective action, at least
by using the derivative expansion method (at zero external momenta), up to
leading order in the Lorentz- and CPT- violating parameter.Comment: 4 pages, version to appear in EP
Two novel evolutionary formulations of the graph coloring problem
We introduce two novel evolutionary formulations of the problem of coloring
the nodes of a graph. The first formulation is based on the relationship that
exists between a graph's chromatic number and its acyclic orientations. It
views such orientations as individuals and evolves them with the aid of
evolutionary operators that are very heavily based on the structure of the
graph and its acyclic orientations. The second formulation, unlike the first
one, does not tackle one graph at a time, but rather aims at evolving a
`program' to color all graphs belonging to a class whose members all have the
same number of nodes and other common attributes. The heuristics that result
from these formulations have been tested on some of the Second DIMACS
Implementation Challenge benchmark graphs, and have been found to be
competitive when compared to the several other heuristics that have also been
tested on those graphs.Comment: To appear in Journal of Combinatorial Optimizatio
Back and forth between social and technical: A collective experience in the transdisciplinary making of sustainable artifacts
From Fablabs to Hackerspaces we now see the emergence of promising venues following open
and collaborative frameworks mixing multiple types of knowledge and skills. They are supported
by an accessibility of additive and subtractive fabrication machines, open source software and
hardware, and many other personal manufacturing tools ushering in low-cost and DiY trends, to
create anything from micro controllers and apps, to wearables and tangible devices in the hype of
highly anticipated Internets of Everything. And, from academia, business or industry, to lay
individuals or pro-amateurs, all are expected to benefit from these spaces and their material and
conceptual platforms, as everyone here is ultimately encouraged to learn how to produce, use,
share, copy and improve assorted objects or systems. This presentation will focus on a collective
experience of learning and making in one of these spaces, by addressing both the final outputs,
and the processes that led to, and occurred during STTF2013 Summer School “Sustainable
Technologies and Transdisciplinary Futures: From Collaborative Design to Digital Fabrication”
(http://sttf2013.iscte-iul.pt/), jointly organized by VitruviusFabLab-IUL (Digital Fabrication
Laboratory) and CIES-IUL (Centre for Research and Studies in Sociology) of ISCTE-IUL
(University Institute of Lisbon), with partners as the JRC-EC, and altLab - Lisbon’s hackerspace.
Gathering graduate students, researchers, and professionals from STS, Design, Social Sciences,
Humanities, Architecture, Computer Science, Communication and Management, the challenge
was to engage all participants within a transdisciplinary collaboration model based on working
groups, while generating sociotechnical debates and tangible outputs that could meet concrete
social needs. From generative design, qualitative social data analysis, or ethical debates, to
digital fabrication, physical computing, or open production exercises, STTF2013 participants
worked in sociotechnical processes of discussion, design, and fabrication of environmentally,
economically, socially and culturally sustainable prototypes for distinct social groups that pass
by, use, or live near two Lisbon's waterfront territories, Cais do Sodré and Cacilhas, considering
issues as cradle to cradle cycles, conviviality, empowerment, modularity, transparency, etc.
Devising these prototypes through such processes allowed for each development stage to be
reflected upon, worked, decided and envisioned through a broad spectrum of disciplinary views.
And its particular mix of social and technical backgrounds and skills, with citizen needs and
local knowledge, resulted in several routes for designing, producing, distributing, and using more
appropriate artifacts. But adding issues or people often apart does not only allow methodological
sharing or collective work, as it also requires careful attention to divergent goals and
backgrounds, dissimilar learning needs, conflicting notions of cooperation, or disparate abilities
to use available technical or social tools. The same logic that enables a transdisciplinary creation
of artifacts from start to end, also provides insights on the most challenging aspects of mingling
conceptual and material processes from social and technical fields in these emerging spaces. An
experience such as STTF2013 present us the opportunity to rethink both the embedding of social
questions and their connected stakeholders within technological outputs, and the paths that
should precede some of the novel heuristic and fabrication frameworks of our nearest futures.info:eu-repo/semantics/acceptedVersio
UM OLHAR SOBRE O ESTADO DE COISAS INCONSTITUCIONAL RECONHECIDO PELO SUPREMO TRIBUNAL FEDERAL DO BRASIL
Abordar fatores de múltiplas ordens e tocar o Sistema Penitenciário e Carcerário nacional é buscar compreender as raízes e constrangimentos da estrutura formal e legal assumida por estabelecimentos penais que, hoje, são reconhecidos como “Estado de Coisas Inconstitucional” por decisão, em 2020, na Arguição de Descumprimento de Preceito Fundamental n. 347 do Excelentíssimo Tribunal de Justiça da República Federativa do Brasil. Em primeiro lugar, aqui temos pesquisa bibliográfica (apoiada na literatura de clássicos políticos e jurídicos, por exemplo, Immanuel Kant, Norberto Bobbio), documental ( vg Constituições de 1824 e 1988, angular e fundamentada) e jurisprudencial (Arguição de Descumprimento de Direitos Fundamentais Preceito - ADPF n. 347 sustentado em construto jusfilosófico), com enfoque qualitativo e interdisciplinar, sobre o reconhecimento do "Estado de Coisas Inconstitucional" a recair sobre o Sistema Prisional no Brasil com vistas à compreensão crítica e reflexiva do ambiente prisional e os vetores que afirmam o “estado de coisas”.Abordar factores de múltiples órdenes y tocar el Sistema Penitenciario y Carcelario nacional es buscar comprender las raíces y condicionantes de la estructura formal y jurídica asumida por los establecimientos penitenciarios que, hoy, se reconocen como un “Estado de Cosas Inconstitucional” por decisión, en 2020, en el Alegato de Incumplimiento del Precepto Fundamental n. 347 de la Honorable Corte de la República Federativa de Brasil. En primer lugar, aquí tenemos investigaciones bibliográficas (apoyadas en la literatura de los clásicos políticos y jurídicos, por ejemplo, Immanuel Kant, Norberto Bobbio), documentales ( vg Constituciones de 1824 y 1988, angulares y sustentadas subyacentemente) y jurisprudenciales (Arguição de Descumprimento of Fundamental Precepto - ADPF n.347 sustentado en un constructo jusfilosófico), con enfoque cualitativo e interdisciplinario, sobre el reconocimiento del "Estado de Cosas Inconstitucional" que recaerá sobre el Sistema Penitenciario en Brasil con vistas a la comprensión crítica y reflexiva del ambiente carcelario y los vectores que afirman el “estado de cosas”.Approaching factors of multiple orders and touching the national Penitentiary and Prison System is to seek to understand the roots and constraints of the formal and legal structure assumed by penal establishments that, today, are recognized as an “Unconstitutional State of Things” due to decision, in 2020, in the Argument of Non-compliance with Fundamental Precept n. 347 at the Honorable Court of the Federative Republic of Brazil. First of all, here we have bibliographical research (supported by literature of political and legal classics, eg, Immanuel Kant, Norberto Bobbio), documental ( vg Constitutions of 1824 and 1988, angular and underlyingly supported) and jurisprudential (Arguição de Descumprimento of Fundamental Precept - ADPF n. 347 sustained in a jusphilosophical construct), with a qualitative and interdisciplinary focus, on the recognition of the "Unconstitutional State of Things" to fall on the Prison System in Brazil with a view to critically and reflexively understanding the prison environment and the vectors that affirm the “state of affairs”.Abordar fatores de múltiplas ordens e tocar o Sistema Penitenciário e Carcerário nacional é buscar compreender as raízes e constrangimentos da estrutura formal e legal assumida por estabelecimentos penais que, hoje, são reconhecidos como “Estado de Coisas Inconstitucional” por decisão, em 2020, na Arguição de Descumprimento de Preceito Fundamental n. 347 do Excelentíssimo Tribunal de Justiça da República Federativa do Brasil. Em primeiro lugar, aqui temos pesquisa bibliográfica (apoiada na literatura de clássicos políticos e jurídicos, por exemplo, Immanuel Kant, Norberto Bobbio), documental ( vg Constituições de 1824 e 1988, angular e fundamentada) e jurisprudencial (Arguição de Descumprimento de Direitos Fundamentais Preceito - ADPF n. 347 sustentado em construto jusfilosófico), com enfoque qualitativo e interdisciplinar, sobre o reconhecimento do "Estado de Coisas Inconstitucional" a recair sobre o Sistema Prisional no Brasil com vistas à compreensão crítica e reflexiva do ambiente prisional e os vetores que afirmam o “estado de coisas”
Concentrations and Isotope Ratios of Dissolved Inorganic Carbon in Denitrifying Environments
We measured the concentration and isotope ratio of dissolved inorganic carbon (DIC) in groundwater associated with denitrification (Corg + NO3- = CO2 + N2) in an agriculturally impacted site in southwestern Michigan. Samples with the lowest nitrate levels also had low dissolved oxygen content and were more depleted in δ13C than background groundwater. All the samples had DIC concentrations in excess of titratable alkalinity. The magnitude of this DIC in excess of alkalinity correlated with a decreasing δ13C attesting to the presence of CO2 derived from organic carbon. Carbon dioxide is one of the by-products of denitrification. Since the carbon isotope ratio of carbon dioxide produced during denitrification can be expected to be similar to that of the substrate consumed in the process, this can serve as a useful tool in monitoring denitrification. The estimated carbon isotope ratio of source carbon added to the DIC pool via denitrification was close to the value obtained for the organic carbon in the aquifer solids, suggesting that the carbon substrate used in denitrification came from soil organic matter. The results provide support for the hypothesis that the concentration and carbon isotope ratios (δ13C) of dissolved inorganic carbon (DIC) in groundwater might be useful to monitor denitrification
Some applications of excited-state-excited-state transition densities
We derive an approximation for transition moments between excited states consistent with the approximations and assumptions normally used to obtain transition moments betwen the ground and excited states in the random-phase approximation and its higher-order approximations. We apply the result to the calculation of the photoionization cross sections of the 23S and 21S metastable states of helium by a numerical analytical continuation of the frequency-dependent polarizability. The procedure completely avoids the need for continuum basis functions. The cross sections agree well with the results of other calculations. We also predict an accurate two-photon decay rate for the 21S metastable state of helium. The entire procedure is immediately applicable to several problems involving photoionization of metastable states of molecules
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