8,034 research outputs found
The scalar glueball spectrum
We discuss scenarios for scalar glueballs using arguments based on sum rules,
spectral decomposition, the approximation, the scales of the
strong interaction and the topology of the flux tubes. We analyze the
phenomenological support of those scenarios and their observational
implications. Our investigations hint a rich low lying glueball spectrum.Comment: 11 pages: New title, figure, table and a more detailed comparison
with experiment
Production of embryos from microspore cultures of Portuguese tronchuda cabbage landraces
Twelve accessions of tronchuda cabbage landraces were tested for their ability to produce embryos through microspore culture in NLN-13 medium. A sample from all the isolations was stained with DAPI for determination of microspore developmental stage. The relationship between the microspore developmental stage and the production of microspore-derived embryos was evaluated.
Embryos were obtained from all the accessions. Considerable variation was observed between isolations with different developmental stage of microspores, accessions and plants within the same accession. The best embryogenic responses occurred in microspore populations with approximately 10 to 89% of binucleate pollen. The highest embryo yield was obtained with one of the ‘Couve de Valhascos’ accessions (0.41 embryos / 1 000 microspores) and the lowest yields with the accessions of ‘Couve Portuguesa’ (less than 0.07 embryos / 1 000 microspores)
Classical Tensors and Quantum Entanglement II: Mixed States
Invariant operator-valued tensor fields on Lie groups are considered. These
define classical tensor fields on Lie groups by evaluating them on a quantum
state. This particular construction, applied on the local unitary group
U(n)xU(n), may establish a method for the identification of entanglement
monotone candidates by deriving invariant functions from tensors being by
construction invariant under local unitary transformations. In particular, for
n=2, we recover the purity and a concurrence related function (Wootters 1998)
as a sum of inner products of symmetric and anti-symmetric parts of the
considered tensor fields. Moreover, we identify a distinguished entanglement
monotone candidate by using a non-linear realization of the Lie algebra of
SU(2)xSU(2). The functional dependence between the latter quantity and the
concurrence is illustrated for a subclass of mixed states parametrized by two
variables.Comment: 23 pages, 4 figure
Insights on KP4 Killer Toxin-like Proteins of Fusarium Species in Interspecific Interactions
KP4 killer toxins are secreted proteins that inhibit cell growth and induce cell death in target organisms. In Fusarium graminearum, KP4-like (KP4L) proteins contribute to fungal virulence in wheat seedling rot and are expressed during Fusarium head blight development. However, fungal KP4L proteins are also hypothesized to support fungal antagonism by permeabilizing cell walls of competing fungi to enable penetration of toxic compounds. Here, we report the differential expression patterns of F. graminearum KP4L genes (Fgkp4l-1, -2, -3 and -4) in a competitive interaction, using Trichoderma gamsii as the antagonist. The results from dual cultures indicate that Fgkp4l-3 and Fgkp4l-4 could participate in the recognition at the distance of the antagonist, while all Fgkp4l genes were highly activated in the pathogen during the physical interaction of both fungi. Only Fgkp4l-4 was up-regulated during the interaction with T. gamsii in wheat spikes. This suggests the KP4L proteins could participate in supporting F. graminearum interspecific interactions, even in living plant tissues. The distribution of KP4L orthologous within the genus Fusarium revealed they are more represented in species with broad host-plant range than in host-specific species. Phylogeny inferred provides evidence that KP4L genes evolved through gene duplications, gene loss and sequence diversification in the genus Fusarium
A participatory public art process in Almada: Agents and values
The impact of public art on the territory has an undeniable cultural dimension since it creates new sensorial and visual agents, with potential social interactivity. In this paper we present and discuss a Portuguese case-study of participated public art, developed for the Caparica Civic Centre (Almada, Portugal) by a team that includes artists (sculptors), anthropologists, local associations and inhabitants. The territory and the community were the main pillars for the conception of a three piece monument, built in a multicultural neighborhood, through a progressive and interactive working methodology, between 2011 and 2013.info:eu-repo/semantics/submittedVersio
Class of dilute granular Couette flows with uniform heat flux
In a recent paper [F. Vega Reyes et al., Phys. Rev. Lett. 104, 028001 (2010)]
we presented a preliminary description of a special class of steady Couette
flows in dilute granular gases. In all flows of this class the viscous heating
is exactly balanced by inelastic cooling. This yields a uniform heat flux and a
linear relationship between the local temperature and flow velocity. The class
(referred to as the LTu class) includes the Fourier flow of ordinary gases and
the simple shear flow of granular gases as special cases. In the present paper
we provide further support for this class of Couette flows by following four
different routes, two of them being theoretical (Grad's moment method of the
Boltzmann equation and exact solution of a kinetic model) and the other two
being computational (molecular dynamics and Monte Carlo simulations of the
Boltzmann equation). Comparison between theory and simulations shows a very
good agreement for the non-Newtonian rheological properties, even for quite
strong inelasticity, and a good agreement for the heat flux coefficients in the
case of Grad's method, the agreement being only qualitative in the case of the
kinetic model.Comment: 15 pages, 10 figures; v2: change of title plus some other minor
change
Dynamically Generated Resonances in the Chiral Unitary Approach to Meson Baryon Interaction
In this talk we report on the use of a chiral unitary approach for the
interaction of the octets of meson and baryon and the octet of mesons with the
decuplet of baryons. Two octets of baryon states and a singlet
are generated dynamically in the first case, resulting in the case of
strangeness in two poles of the scattering matrix close to the nominal
resonance. In the second case many resonances are also
generated, among them an exotic baryon with S=1 corresponding to a
resonance. We make suggestions of experiments which could show evidence for the
existence of these states.Comment: Talk at the MENU04 Symposium, Beijing, September 200
Segregation of an intruder in a heated granular dense gas
A recent segregation criterion [V. Garz\'o, Phys. Rev. E \textbf{78},
020301(R) (2008)] based on the thermal diffusion factor of an
intruder in a heated granular gas described by the inelastic Enskog equation is
revisited. The sign of provides a criterion for the transition
between the Brazil-nut effect (BNE) and the reverse Brazil-nut effect (RBNE).
The present theory incorporates two extra ingredients not accounted for by the
previous theoretical attempt. First, the theory is based upon the second Sonine
approximation to the transport coefficients of the mass flux of intruder.
Second, the dependence of the temperature ratio (intruder temperature over that
of the host granular gas) on the solid volume fraction is taken into account in
the first and second Sonine approximations. In order to check the accuracy of
the Sonine approximation considered, the Enskog equation is also numerically
solved by means of the direct simulation Monte Carlo (DSMC) method to get the
kinetic diffusion coefficient . The comparison between theory and
simulation shows that the second Sonine approximation to yields an
improvement over the first Sonine approximation when the intruder is lighter
than the gas particles in the range of large inelasticity. With respect to the
form of the phase diagrams for the BNE/RBNE transition, the kinetic theory
results for the factor indicate that while the form of these diagrams
depends sensitively on the order of the Sonine approximation considered when
gravity is absent, no significant differences between both Sonine solutions
appear in the opposite limit (gravity dominates the thermal gradient). In the
former case (no gravity), the first Sonine approximation overestimates both the
RBNE region and the influence of dissipation on thermal diffusion segregation.Comment: 9 figures; to be published in Phys. Rev.
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