623 research outputs found
Correlations in hot and dense quark matter
We present a relativistic three-body equation to investigate three-quark
clusters in hot and dense quark matter. To derive such an equation we use the
Dyson equation approach. The equation systematically includes the Pauli
blocking factors as well as the self energy corrections of quarks. Special
relativity is realized through the light front form. Presently we use a
zero-range force and investigate the Mott transition.Comment: 6 pages, 4 figure, Few-Body Systems style file
Dynamics of few-body states in a medium
Strongly interacting matter such as nuclear or quark matter leads to few-body
bound states and correlations of the constituents. As a consequence quantum
chromodynamics has a rich phase structure with spontaneous symmetry breaking,
superconductivity, condensates of different kinds. All this appears in many
astrophysical scenarios. Among them is the formation of hadrns during the early
stage of the Universe, the structure of a neutron star, the formation of nuclei
during a supernova explosion. Some of these extreme conditions can be simulated
in heavy ion colliders. To treat such a hot and dense system we use the Green
function formalism of many-body theory. It turns out that a systematic Dyson
expansion of the Green functions leads to modified few-body equations that are
capable to describe phase transitions, condensates, cluster formation and more.
These equations include self energy corrections and Pauli blocking. We apply
this method to nonrelativistic and relativistic matter. The latter one is
treated on the light front. Because of the medium and the inevitable truncation
of space, the few-body dynamics and states depend on the thermodynamic
parameters of the medium.Comment: 3 pages, 2 figures, talk presented at the 19th European Conference on
Few-Body System
A stopped Delta-Matter Source in Heavy Ion Collisions at 10 GeV/n
We predict the formation of highly dense baryon-rich resonance matter in
Au+Au collisions at AGS energies. The final pion yields show observable signs
for resonance matter. The Delta(1232) resonance is predicted to be the dominant
source for pions of small transverse momenta. Rescattering effects --
consecutive excitation and deexcitation of Deltas -- lead to a long apparent
lifetime (> 10 fm/c) and rather large volumina (several 100 fm^3) of the
Delta-matter state. Heavier baryon resonances prove to be crucial for reaction
dynamics and particle production at AGS.Comment: 17 pages, 5 postscript figures, uses psfig.sty and revtex.st
Sheep predation : characteristics and risk factors
Predation has always been an important problem in extensive sheep farms, causing serious economic losses to the farmers. Official predation reports have recently been decreasing in the District of Pisa, in spite of the presence of two wolf packs in the area. The aim of the present research was to obtain reliable information on the characteristics of predation and to estimate the effectiveness of existing prevention methods in sheep farms of the southern District of Pisa, in order to set up predictive models for an improved and more focused prevention plan and support interventions by public authorities. On-farm surveys were carried out in 73 semi-extensive sheep farms. Predation events were reported by 75.3% of the farmers. Wolves seemed to be responsible for most of those events, although their actual role could be confirmed only in 34% of cases. Most of the events occurred in spring and 85.1% of them were concentrated during night time. The average number of sheep killed during each attack was 7.05. In 22.3% of cases, the number of sheep killed was 65 10. Proximity to protected areas and the presence of thick vegetation cover significantly affected the probability of a farm being subjected to chronic predation. Farm size was significantly higher in those cases. No clear indication about the effectiveness of prevention methods could be obtained from our survey. The results of this investigation highlighted the impact of predation in the Southern District of Pisa and emphasized the need for finding technical and political solutions to this problem. Attention should be focused on large farms, with thick vegetation cover and located close to protected areas. Further investigations should be carried out in order to test the effectiveness of suitable prevention methods in these farms
A series of new conjugated oligothiophenes for organic electronics
Thiophene oligomers and polymers can be found in a huge number of materials with applications in the field of Organic Electronics. Chemical and electrochemical syntheses along with electrochemical studies and complete characterization of a series of new conjugated oligothiophene derivatives are reported. Two different molecular architectures, D-A (donor-acceptor) and A-D-A (acceptor-donor-acceptor), were taken into account. The results from voltammetric experiments and optical studies confirm the close relationship between the structure of these compounds and their electrochemical behaviour. This series of oligothiophenes shows low bandgaps, a mandatory requirement for their use in Organic Electronics, and, clearly, they are promising candidates for future synthetic studies in order to modify their optical and electrochemical properties to achieve better performances as organic semiconductors
Dibaryons with Strangeness: their Weak Nonleptonic Decay using SU(3) Symmetry and how to find them in Relativistic Heavy-Ion Collisions
Weak SU(3) symmetry is successfully applied to the weak hadronic decay
amplitudes of octet hyperons. Weak nonmesonic and mesonic decays of various
dibaryons with strangeness, their dominant decay modes, and lifetimes are
calculated. Production estimates for BNL's Relativistic Heavy-Ion Collider are
presented employing wave function coalescence. Signals for detecting strange
dibaryon states in heavy-ion collisions and revealing information about the
unknown hyperon-hyperon interactions are outlined.Comment: 4 pages, 2 figures, uses RevTeX, discussion about the model of the
weak decay and experimental signals extended, references update
Physiological And Transcriptional Analyses Of Developmental Stages Along Sugarcane Leaf
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Background: Sugarcane is one of the major crops worldwide. It is cultivated in over 100 countries on 22 million ha. The complex genetic architecture and the lack of a complete genomic sequence in sugarcane hamper the adoption of molecular approaches to study its physiology and to develop new varieties. Investments on the development of new sugarcane varieties have been made to maximize sucrose yield, a trait dependent on photosynthetic capacity. However, detailed studies on sugarcane leaves are scarce. In this work, we report the first molecular and physiological characterization of events taking place along a leaf developmental gradient in sugarcane. Results: Photosynthetic response to CO2 indicated divergence in photosynthetic capacity based on PEPcase activity, corroborated by activity quantification (both in vivo and in vitro) and distinct levels of carbon discrimination on different segments along leaf length. Additionally, leaf segments had contrasting amount of chlorophyll, nitrogen and sugars. RNA-Seq data indicated a plethora of biochemical pathways differentially expressed along the leaf. Some transcription factors families were enriched on each segment and their putative functions corroborate with the distinct developmental stages. Several genes with higher expression in the middle segment, the one with the highest photosynthetic rates, were identified and their role in sugarcane productivity is discussed. Interestingly, sugarcane leaf segments had a different transcriptional behavior compared to previously published data from maize. Conclusion: This is the first report of leaf developmental analysis in sugarcane. Our data on sugarcane is another source of information for further studies aiming to understand and/or improve C-4 photosynthesis. The segments used in this work were distinct in their physiological status allowing deeper molecular analysis. Although limited in some aspects, the comparison to maize indicates that all data acquired on one C-4 species cannot always be easily extrapolated to other species. However, our data indicates that some transcriptional factors were segment-specific and the sugarcane leaf undergoes through the process of suberizarion, photosynthesis establishment and senescence.15Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2012/23345-0
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