1,373 research outputs found
Toarcian GSSP candidate: the Peniche section at Ponta do TrovĂŁo
The Peniche section (Ponta do TrovĂŁo) in Portugal is presented as potential stratotype (GSSP) for the Pliensbachian/Toarcian boundary. The lithostratigraphic succession is described and the chronostratigraphy, based on ammonite assemblages, is presented; the change in foraminifera assemblages occurs later, only at the base of beds 16 (base of Semicelatum Subzone, Crosbeyi ? Horizon).
An extensive bibliographical list of all scientific articles containing specific reference to this stratigraphic boundary, whether from the Lusitanian or Algarve basins, is also presented
Immigration Enforcement and Fairness to Would-Be Immigrants
This chapter argues that governments have a duty to take reasonably effective and humane steps to minimize the occurrence of unauthorized migration and stay. While the effects of unauthorized migration on a countryâs citizens and institutions have been vigorously debated, the literature has largely ignored duties of fairness to would-be immigrants. It is argued here that failing to take reasonable steps to prevent unauthorized migration and stay is deeply unfair to would-be immigrants who are not in a position to bypass visa regulations. Importantly, the argument here is orthogonal to the debate as to how much and what kinds of immigration ought to be allowed
FaciÚs, biostratigraphie et paléogéographie du Jurassique portugais
The facies distribution along the Jurassic stages in an already well established stratigraphic frame is defined for the three portuguese basins: North of Tagus, Santiago de Cacém and Algarve.
The deposits are organized in two sedimentary cycles. The first one from the Liassic to Calovian shows, in the Tagus Basin, a transgression from NW which did not surpass the Meseta present limits. The iniatilly brackish deposits only changed to marine by the end of Lotharingian.
The sedimentation, mainly marly during the Liassic became more calcareous since the Aalenian. During the Dogger the basin differentiated into platform deposits towards East and South and open sea zone towards West. This zone underwent a progressive reduction and, during the Callovian, two small basins were individualized: Cabo Mondego basin in the North and Serra de El-Rei-Montejunto in the South. It is from the latter that the second sedimentary cycle (Middle Oxfordian-Portlandian) developed with open sea deposits along the SintraâTorres Vedras axis surrounded by platform and litoral brackish formations.
During the first sedimentary cycle only litoral platform deposits are known in Santiago de Cacém and Algarve basins. During the second sedimentary cycle temporary sea open deposits are known in Santiago de Cacém and Central Algarve
Development of a framework for metabolic pathway analysis-driven strain optimization methods
Genome-scale metabolic models (GSMMs) have become important assets for rational design of compound overproduction using microbial cell factories. Most computational strain optimization methods (CSOM) using GSMMs, while useful in metabolic engineering, rely on the definition of questionable cell objectives, leading to some bias. Metabolic pathway analysis approaches do not require an objective function. Though their use brings immediate advantages, it has mostly been restricted to small scale models due to computational demands. Additionally, their complex parameterization and lack of intuitive tools pose an important challenge towards making these widely available to the community. Recently, MCSEnumerator has extended the scale of these methods, namely regarding enumeration of minimal cut sets, now able to handle GSMMs. This work proposes a tool implementing this method as a Java library and a plugin within the OptFlux metabolic engineering platform providing a friendly user interface. A standard enumeration problem and pipeline applicable to GSMMs is proposed, making use by the community simpler. To highlight the potential of these approaches, we devised a case study for overproduction of succinate, providing a phenotype analysis of a selected strategy and comparing robustness with a selected solution from a bi-level CSOM.The authors thank the project âDeYeastLibraryâDesigner yeast strain library optimized for metabolic engineering applicationsâ, Ref. ERA-IB-2/0003/2013, funded by national funds through âFundação para a CiĂȘncia e Tecnologia / MinistĂ©rio da CiĂȘncia, Tecnologia e Ensino Superiorâ.info:eu-repo/semantics/publishedVersio
Relativistic effects and quasipotential equations
We compare the scattering amplitude resulting from the several quasipotential
equations for scalar particles. We consider the Blankenbecler-Sugar, Spectator,
Thompson, Erkelenz-Holinde and Equal-Time equations, which were solved
numerically without decomposition into partial waves. We analyze both
negative-energy state components of the propagators and retardation effects. We
found that the scattering solutions of the Spectator and the Equal-Time
equations are very close to the nonrelativistic solution even at high energies.
The overall relativistic effect increases with the energy. The width of the
band for the relative uncertainty in the real part of the scattering
matrix, due to different dynamical equations, is largest for
backward-scattering angles where it can be as large as 40%.Comment: Accepted for publication in Phys. Rev.
Astrobiological Complexity with Probabilistic Cellular Automata
Search for extraterrestrial life and intelligence constitutes one of the
major endeavors in science, but has yet been quantitatively modeled only rarely
and in a cursory and superficial fashion. We argue that probabilistic cellular
automata (PCA) represent the best quantitative framework for modeling
astrobiological history of the Milky Way and its Galactic Habitable Zone. The
relevant astrobiological parameters are to be modeled as the elements of the
input probability matrix for the PCA kernel. With the underlying simplicity of
the cellular automata constructs, this approach enables a quick analysis of
large and ambiguous input parameters' space. We perform a simple clustering
analysis of typical astrobiological histories and discuss the relevant boundary
conditions of practical importance for planning and guiding actual empirical
astrobiological and SETI projects. In addition to showing how the present
framework is adaptable to more complex situations and updated observational
databases from current and near-future space missions, we demonstrate how
numerical results could offer a cautious rationale for continuation of
practical SETI searches.Comment: 37 pages, 11 figures, 2 tables; added journal reference belo
Collision, explosion and collapse of homoclinic classes
Homoclinic classes of generic -diffeomorphisms are maximal transitive
sets and pairwise disjoint. We here present a model explaining how two
different homoclinic classes may intersect, failing to be disjoint. For that we
construct a one-parameter family of diffeomorphisms with
hyperbolic points and having nontrivial homoclinic classes, such that,
for , the classes of and are disjoint, for , they are equal,
and, for , their intersection is a saddle-node.Comment: This is the final version, accepted in 200
Stratigraphie du Dogger et crise lusitanienne dans la Serra de Candeeiros
New elements about the stratigraphy of the Serra de Candeeiros Dogger and Lower «Lusitanian» are presented.
The Lower Aalenian was recognized for the first time. Bathonian (more than 50 metres thick) is dated on brachiopods and foraminifera. It corresponds to a series of massive micritic, biodetritical, coral-reef, chaetetid, bryozoa and oolitic-limestones. Callovian (120 m) begins by whitish or yellowish limestones with ammonites and brachiopods of the Gracilis zone. It is followed by regressive limestone sequences ending with thick oncolitic layers. The «Lusitanian» base is formed by greyish lagoon brackish limestones; it lies unconformably on the Dogger, with or without angular and/or cartographic unconformity.
This radical facies change is related to tectonic deformation of several blocks between the Nazaré and Tagus faults during Oxfordian times
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