1,566 research outputs found
Strong Pionic Decays From a Spectroscopic Quark Model
From a refined non-relativistic quark model that fits the baryonic low-energy
spectrum the study of strong pion decay processes within an elementary emission
model scheme points out the need of incorporating size-contributing components
into the baryon wave functions. In particular the effect of a (qqq qantiq)
component is investigated in the framework of a quark pair creation model.Comment: 26 pages, 9 figures (1 postscript file), LaTe
Model analysis of the world data on the pion transition form factor
We discuss the impact of recent Belle data on our description of the pion
transition form factor based on the assumption that a perturbative formalism
and a nonperturbative one can be matched in a physically acceptable manner at a
certain hadronic scale . We discuss the implications of the different
parameters of the model in comparing with world data and conclude that within
experimental errors our description remains valid. Thus we can assert that the
low nonperturbative description together with an additional term
at the matching scale have a strong influence on the behavior up to very
high values of .Comment: 6 pages and 3 figures. Contains a comparison with other models and
additional reference
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Register analysis and ESP pedagogy: Noun-phrase modification in a corpus of English for military navy submariners
© 2018 Elsevier Ltd Research in Maritime English (ME) has paid no attention to the range of texts and language to which Navy submariners are exposed during their training and professional careers. This research looked at Noun Phrase (NP)modification patterns in a longitudinal corpus of Submarine English (SE) professional texts in the Cartagena Military Submarine Corpus (CMSC). Using a combination of quantitative and qualitative analyses, we found that SE is characterised by heavy nominal premodification, low adjective premodification, low prepositional phrase postmodification and by the predominant use of appositive nouns in postmodifying slots. These distinctive features of SE call for a register-sensitive pedagogy that unpack these characteristics and present them in context. We argue that the contribution of corpus linguistics is essential to explore registers which, for different reasons, have not been addressed or described linguistically in the past. Similarly, we maintain that the examination and teaching of NPs is essential to understand current trends in professional writing and communication
The topology of vitronectin: A complementary feature for neuroblastoma risk classification based on computer‐aided detection
Tumors are complex networks of constantly interacting elements: tumor cells, stromal cells, immune and stem cells, blood/lympathic vessels, nerve fibers and extracellular matrix components. These elements can influence their microenvironment through mechanical and physical signals to promote tumor cell growth. To get a better understanding of tumor biology, cooperation between multidisciplinary fields is needed. Diverse mathematic computations and algorithms have been designed to find prognostic targets and enhance diagnostic assessment. In this work, we use computational digital tools to study the topology of vitronectin, a glycoprotein of the extracellular matrix. Vitronectin is linked to angiogenesis and migration, two processes closely related to tumor cell spread. Here, we investigate whether the distribution of this molecule in the tumor stroma may confer mechanical properties affecting neuroblastoma aggressiveness. Combining image analysis and graph theory, we analyze different topological features that capture the organizational cues of vitronectin in histopathological images taken from human samples. We find that the Euler number and the branching of territorial vitronectin, two topological features, could allow for a more precise pretreatment risk stratification to guide treatment strategies in neuroblastoma patients. A large amount of recently synthesized VN would create migration tracks, pinpointed by both topological features, for malignant neuroblasts, so that dramatic change in the extracellular matrix would increase tumor aggressiveness and worsen patient outcomes
Nucleon Electromagnetic Form Factors in a Relativistic Quark Pair Creation Model
We study the effects of the | qqq q\bar{q} > component of the hadronic wave function on the description of the electromagnetic structure of the nucleon. Starting with a qqq baryonic wave function which describes the baryonic and mesonic low energy spectrum, the extra q\bar{q} pair is generated through a relativistic version of the 3P_0 model. It is shown that this model leads to a renormalization of the quark mass that allows one to construct a conserved electromagnetic current. We conclude that these dynamical relativistic corrections play an important role in reproducing the Q2 dependence of the electromagnetic form factors at low Q^2
Magnetism and half-metallicity at the O surfaces of ceramic oxides
The occurence of spin-polarization at ZrO, AlO and MgO
surfaces is proved by means of \textit{ab-initio} calculations within the
density functional theory. Large spin moments, as high as 1.56 , develop
at O-ended polar terminations, transforming the non-magnetic insulator into a
half-metal. The magnetic moments mainly reside in the surface oxygen atoms and
their origin is related to the existence of holes of well-defined spin
polarization at the valence band of the ionic oxide. The direct relation
between magnetization and local loss of donor charge makes possible to extend
the magnetization mechanism beyond surface properties
No-core shell model for 48-Ca, 48-Sc and 48-Ti
We report the first no-core shell model results for , and
with derived and modified two-body Hamiltonians. We use an oscillator
basis with a limited range around and a limited model space up to . No single-particle
energies are used. We find that the charge dependence of the bulk binding
energy of eight A=48 nuclei is reasonably described with an effective
Hamiltonian derived from the CD-Bonn interaction while there is an overall
underbinding by about 0.4 MeV/nucleon. However, the resulting spectra exhibit
deficiencies that are anticipated due to: (1) basis space limitations and/or
the absence of effective many-body interactions; and, (2) the absence of
genuine three-nucleon interactions. We then introduce additive
isospin-dependent central terms plus a tensor force to our Hamiltonian and
achieve accurate binding energies and reasonable spectra for all three nuclei.
The resulting no-core shell model opens a path for applications to the
double-beta () decay process.Comment: Revised content and added reference
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