531 research outputs found
Modelling single nucleotide effects in phosphoglucose isomerase on dispersal in the Glanville fritillary butterfly: coupling of ecological and evolutionary dynamics
Dispersal comprises a complex life-history syndrome that influences the demographic dynamics of especially those species that live in fragmented landscapes, the structure of which may in turn be expected to impose selection on dispersal. We have constructed an individual-based evolutionary sexual model of dispersal for species occurring as metapopulations in habitat patch networks. The model assumes correlated random walk dispersal with edge-mediated behaviour (habitat selection) and spatially correlated stochastic local dynamics. The model is parametrized with extensive data for the Glanville fritillary butterfly. Based on empirical results for a single nucleotide polymorphism (SNP) in the phosphoglucose isomerase (Pgi) gene, we assume that dispersal rate in the landscape matrix, fecundity and survival are affected by a locus with two alleles, A and C, individuals with the C allele being more mobile. The model was successfully tested with two independent empirical datasets on spatial variation in Pgi allele frequency. First, at the level of local populations, the frequency of the C allele is the highest in newly established isolated populations and the lowest in old isolated populations. Second, at the level of sub-networks with dissimilar numbers and connectivities of patches, the frequency of C increases with decreasing network size and hence with decreasing average metapopulation size. The frequency of C is the highest in landscapes where local extinction risk is high and where there are abundant opportunities to establish new populations. Our results indicate that the strength of the coupling of the ecological and evolutionary dynamics depends on the spatial scale and is asymmetric, demographic dynamics having a greater immediate impact on genetic dynamics than vice versa
Purely-long-range bound states of HeHe
We predict the presence and positions of purely-long-range bound states of
HeHe near the atomic
limits. The results of the full multichannel and approximate models are
compared, and we assess the sensitivity of the bound states to atomic
parameters characterizing the potentials. Photoassociation to these
purely-long-range molecular bound states may improve the knowledge of the
scattering length associated with the collisions of two ultracold
spin-polarized He atoms, which is important for studies of
Bose-Einstein condensates.Comment: 16 pages, 5 figure
Supersymmetric economical 3-3-1 model
The supersymmetric extension of the economical 3-3-1 model is presented. The
constraint equations and the gauge boson identification establish a relation
between the vacuum expectation values (VEVs) at the top and bottom elements of
the Higgs triplet and its supersymmetric counterpart .
Because of this relation, the exact diagonalization of neutral gauge boson
sector has been performed. The gauge bosons and their associated Goldstone ones
mix in the same way as in non-supersymmetric version. This is also correct in
the case of gauginos. The eigenvalues and eigenstates in the Higgs sector are
derived. The model contains a heavy neutral Higgs boson with mass equal to
those of the neutral non-Hermitian gauge boson and a charged scalar with
mass equal to those of the boson in the standard model, i. e. . This result is in good agreement with the present
estimation: GeV, CL= 95 %. We also show that the boson
sector and the fermion sector gain masses in the same way as in the
non-supersymmetric case.Comment: 33 page
Cluster Spin Glass Distribution Functions in LaSrCuO
Signatures of the cluster spin glass have been found in a variety of
experiments, with an effective onset temperature that is frequency
dependent. We reanalyze the experimental results and find that they are
characterized by a distribution of activation energies, with a nonzero glass
transition temperature . While the distribution of activation
energies is the same, the distribution of weights depends on the process.
Remarkably, the weights are essentially doping independent.Comment: 5 pages, 5 ps figure
Banking union in historical perspective: the initiative of the European Commission in the 1960s-1970s
This article shows that planning for the organization of EU banking regulation and supervision did not just appear on the agenda in recent years with discussions over the creation of the eurozone banking union. It unveils a hitherto neglected initiative of the European Commission in the 1960s and early 1970s. Drawing on extensive archival work, this article explains that this initiative, however, rested on a number of different assumptions, and emerged in a much different context. It first explains that the Commission's initial project was not crisis-driven; that it articulated the link between monetary integration and banking regulation; and finally that it did not set out to move the supervisory framework to the supranational level, unlike present-day developments
Knowledge politics and new converging technologies: a social epistemological perspective
The “new converging technologies” refers to the prospect of advancing the human condition by the integrated study and application of nanotechnology, biotechnology, information technology and the cognitive sciences - or “NBIC”. In recent years, it has loomed large, albeit with somewhat different emphases, in national science policy agendas throughout the world. This article considers the political and intellectual sources - both historical and contemporary - of the converging technologies agenda. Underlying it is a fluid conception of humanity that is captured by the ethically challenging notion of “enhancing evolution”
Diversity of Agaricales (Basidiomycota) in the Reserva Biológica Walter Egler, Amazonas, Brazil
A study of the order Agaricales Clements (Hymenomycetes, Basidiomycotina), occurring in the Reserva Biológica Walter Egler was carried out from December 2000 to June 2001. The area of study is situated at Road AM-010, Manaus-Itacoatiara, km 64, Latitude 02° 43' S and Longitude 59° 47' W, Rio Preto da Eva, in the State of Amazonas, with a total area of 709 ha of terra firme rain forest. The fungi collected were identified based on traditional methodology for identification of Agaricales. A total of 39 species were studied, distributed in 13 genera and six families: Polyporaceae: Pleurotus sp.; Hygrophoraceae: Hygrocybe cf. megistospora, Hygrocybe aff. miniceps, Hygrocybe occidentalis var. scarletina and eight indeterminate species of Hygrocybe; Tricholomataceae: Clitocybe sp., Hydropus sp.1 and Hydropus sp.2, Macrocystidia sp., Marasmiellus sp., Marasmius bellus, Marasmius haedinus var. haedinus, Marasmius cf. leoninus, Marasmius cf. mazatecus, Marasmius cf. ruber, Marasmius cf. setulosifolius, Marasmius tageticolor, Marasmius cf. variabiliceps var. variabiliceps, Marasmius sp.1, Marasmius sp.2, Marasmius sp.3 and Marasmius sp.4, Tricholoma sp.; Agaricaceae: Agaricus sp.1 and Agaricus sp.2, Lepiota sp., Cystoderma sp.; Entolomataceae: Entoloma cf. azureoviride, Entoloma cf. cystidiophorum, Entoloma strigosissima, Entoloma sp.; Russulaceae: Lactarius panuoides. Entoloma azureoviride, Hygrocybe miniceps, Lactarius panuoides, Marasmius cf. mazatecus, Marasmius cf. setulosifolius and Marasmius variabiliceps var. variabiliceps, apparently are here cited for the first time from Brazil. With exception of Marasmius tageticolor, all species are cited here for the first time as occurring in Egler Forest. The tables with the species occurrence, in accordance with the topographical gradient (sand bank, incline, plateau) and its respective habitat, are supplied.", 'enFoi realizado um estudo dos representantes da Ordem Agaricales Clements (Hymenomycetes, Basidiomycotina), ocorrentes na Reserva Biológica Walter Egler, situada na Estrada AM-010, Manaus-Itacoatiara, Km 64, Latitude 02° 43' S e Longitude 59° 47' W, Rio Preto da Eva, Amazonas. A área abrange 709 ha de floresta de terra firme primária. As coletas foram realizadas no período de dezembro de 2000 a junho de 2001 e seguiu-se a metodologia usual para identificação de Agaricales. Foram estudadas um total de 39 espécies, distribuídas em 13 gêneros e seis famíliasPolyporaceaePleurotus sp.; HygrophoraceaeHygrocybe cf. megistospora, Hygrocybe aff. miniceps, Hygrocybe occidentalis var. scarletina, e mais oito espécies de Hygrocybe indeterminadas; TricholomataceaeClitocybe sp., Hydropus sp.1 e Hydropus sp.2, Macrocystidia sp., Marasmiellus sp., Marasmius bellus, Marasmius haedinus var. haedinus,Marasmius cf. leoninus, Marasmius cf. mazatecus, Marasmius cf. ruber,Marasmius cf. setulosifolius, Marasmius tageticolor, Marasmius cf. variabiliceps var. variabiliceps, Marasmius sp.1, Marasmius sp.2, Marasmius sp.3 e Marasmius sp.4, Tricholoma sp.; AgaricaceaeAgaricus sp.1 e Agaricus sp.2, Lepiota sp., Cystoderma sp.; EntolomataceaeEntoloma cf. azureoviride, Entoloma cf. cystidiophorum, Entoloma strigosissima, Entoloma sp.; RussulaceaeLactarius panuoides. Destas, Entoloma azureoviride, Hygrocybe miniceps, Lactarius panuoides, Marasmius cf. mazatecus, Marasmius cf. setulosifolius e Marasmius variabiliceps var. variabiliceps, provavelmente, estão sendo aqui citadas pela primeira vez, para o Brasil. Com exceção de Marasmius tageticolor, as demais espécies são citadas pela primeira vez, para a Reserva Egler. São fornecidas tabelas com a ocorrência das espécies de acordo com o gradiente topográfico (baixio, vertente, platô) e seus respectivos habitats
Олесь Бабій - співець слави січових стрільців
The Salamanca Formation of the San Jorge Basin (Patagonia, Argentina) preserves critical records of Southern Hemisphere Paleocene biotas, but its age remains poorly resolved, with estimates ranging from Late Cretaceous to middle Paleocene. We report a multi-disciplinary geochronologic study of the Salamanca Formation and overlying Río Chico Group in the western part of the basin. New constraints include (1) an 40Ar/39Ar age determination of 67.31 ± 0.55 Ma from a basalt flow underlying the Salamanca Formation, (2) micropaleontological results indicating an early Danian age for the base of the Salamanca Formation, (3) laser ablation HR-MC-ICP-MS (high resolution-multi collector-inductively coupled plasma-mass spectrometry) U-Pb ages and a high-resolution TIMS (thermal ionization mass spectrometry) age of 61.984 ± 0.041(0.074)[0.100] Ma for zircons from volcanic ash beds in the Peñas Coloradas Formation (Río Chico Group), and (4) paleomagnetic results indicating that the Salamanca Formation in this area is entirely of normal polarity, with reversals occurring in the Río Chico Group. Placing these new age constraints in the context of a sequence stratigraphic model for the basin, we correlate the Salamanca Formation in the study area to Chrons C29n and C28n, with the Banco Negro Inferior (BNI), a mature widespread fossiliferous paleosol unit at the top of the Salamanca Formation, corresponding to the top of Chron C28n. The diverse paleobotanical assemblages from this area are here assigned to C28n (64.67–63.49 Ma), ∼2–3 million years older than previously thought, adding to growing evidence for rapid Southern Hemisphere floral recovery after the Cretaceous-Paleogene extinction. Important Peligran and “Carodnia” zone vertebrate fossil assemblages from coastal BNI and Peñas Coloradas exposures are likely older than previously thought and correlate to the early Torrejonian and early Tiffanian North American Land Mammal Ages, respectively
The 3-3-1 model with S_4 flavor symmetry
We construct a 3-3-1 model based on family symmetry S_4 responsible for the
neutrino and quark masses. The tribimaximal neutrino mixing and the diagonal
quark mixing have been obtained. The new lepton charge \mathcal{L} related to
the ordinary lepton charge L and a SU(3) charge by L=2/\sqrt{3} T_8+\mathcal{L}
and the lepton parity P_l=(-)^L known as a residual symmetry of L have been
introduced which provide insights in this kind of model. The expected vacuum
alignments resulting in potential minimization can origin from appropriate
violation terms of S_4 and \mathcal{L}. The smallness of seesaw contributions
can be explained from the existence of such terms too. If P_l is not broken by
the vacuum values of the scalar fields, there is no mixing between the exotic
and the ordinary quarks at the tree level.Comment: 20 pages, revised versio
Stability of metallic stripes in the extended one-band Hubbard model
Based on an unrestricted Gutzwiller approximation (GA) we investigate the
stripe orientation and periodicity in an extended one-band Hubbard model. A
negative ratio between next-nearest and nearest neighbor hopping t'/t, as
appropriate for cuprates, favors partially filled (metallic) stripes for both
vertical and diagonal configurations. At around optimal doping diagonal
stripes, site centered (SC) and bond centered (BC) vertical stripes become
degenerate suggesting strong lateral and orientational fluctuations. We find
that within the GA the resulting phase diagram is in agreement with experiment
whereas it is not in the Hartree-Fock approximation due to a strong
overestimation of the stripe filling. Results are in agreement with previous
calculations within the three-band Hubbard model but with the role of SC and BC
stripes interchanged.Comment: 10 pages, 8 figure
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