2,638 research outputs found
Regularization, Renormalization and Range: The Nucleon-Nucleon Interaction from Effective Field Theory
Regularization and renormalization is discussed in the context of low-energy
effective field theory treatments of two or more heavy particles (such as
nucleons). It is desirable to regulate the contact interactions from the outset
by treating them as having a finite range. The low energy physical observables
should be insensitive to this range provided that the range is of a similar or
greater scale than that of the interaction. Alternative schemes, such as
dimensional regularization, lead to paradoxical conclusions such as the
impossibility of repulsive interactions for truly low energy effective theories
where all of the exchange particles are integrated out. This difficulty arises
because a nonrelativistic field theory with repulsive contact interactions is
trivial in the sense that the matrix is unity and the renormalized coupling
constant zero. Possible consequences of low energy attraction are also
discussed. It is argued that in the case of large or small scattering lengths,
the region of validity of effective field theory expansion is much larger if
the contact interactions are given a finite range from the beginning.Comment: 7 page
Complex collective states in a one-dimensional two-atom system
We consider a pair of identical two-level atoms interacting with a scalar
field in one dimension, separated by a distance . We restrict our
attention to states where one atom is excited and the other is in the ground
state, in symmetric or anti-symmetric combinations. We obtain exact collective
decaying states, belonging to a complex spectral representation of the
Hamiltonian. The imaginary parts of the eigenvalues give the decay rates, and
the real parts give the average energy of the collective states. In one
dimension there is strong interference between the fields emitted by the atoms,
leading to long-range cooperative effects. The decay rates and the energy
oscillate with the distance . Depending on , the decay rates
will either decrease, vanish or increase as compared with the one-atom decay
rate. We have sub- and super-radiance at periodic intervals. Our model may be
used to study two-cavity electron wave-guides. The vanishing of the collective
decay rates then suggests the possibility of obtaining stable configurations,
where an electron is trapped inside the two cavities.Comment: 14 pages, 14 figures, submitted to Phys. Rev.
KARYOMORPHOLOGY OF THE PHILIPPINE ROCK GOBY, Glossogobius giuris (GOBIIDAE) FROM LAKE TAAL AND SOME RIVERS OF CAVITE, LUZON ISLAND
The karyomorphology of Glossogobius giuris (Gobiidae) obtained from Lake Taal and some rivers of Cavite in Luzon Island, Philippines was described. Metaphase chromosome analysis (colchicine-sodium citrate-Carnoy's fixation-Giemsa staining procedures) of the hematopoitetic cells in the anterior kidneys revealed that the diploid chromosome number was 2n=46 (46A). Fundamental Number (FN) is also 46, since all chromosomal morphology were acrocentrics without any distinguishable heteromorphic pair of chromosomes in the metaphase spreads from both dry and wet preparations. This study confirms previous reports on the chromosomal sets of G. giuris from India. Keywords : Philippines / Lake Taal / Genetics / Karyomorphology / Glossogobius giuri
Karyomorphology of the Philippine Rock Goby, Glossogobius Giuris (Gobiidae) From Lake Taal and Some Rivers of Cavite, Luzon Island
The karyomorphology of Glossogobius giuris (Gobiidae) obtained from Lake Taal and some rivers of Cavite in Luzon Island, Philippines was described. Metaphase chromosome analysis (colchicine-sodium citrate-Carnoy's fixation-Giemsa staining procedures) of the hematopoitetic cells in the anterior kidneys revealed that the diploid chromosome number was 2n=46 (46A). Fundamental Number (FN) is also 46, since all chromosomal morphology were acrocentrics without any distinguishable heteromorphic pair of chromosomes in the metaphase spreads from both dry and wet preparations. This study confirms previous reports on the chromosomal sets of G. giuris from India
Analysis of Solar Passive Techniques and Natural Ventilation Concepts in a Residential Building Including CFD Simulation
The European residential building sector accounts for over 40% of final energy consumption in the European Union member states. Therefore, an improvement of buildings energy efficiency represents a great instrument to reduce CO2 emissions. The first step to increase energy performance in buildings is to use passive strategies, such as orientation, natural ventilation or envelope optimisation. This paper presents an analysis of solar passive techniques and natural ventilation concepts in a case study: La Clota residential building, located near Barcelona (Spain). It has been carried out a comparative analysis of La Clota building in order to evaluate its energy and environmental performance with respect to a conventional building and also with respect to another hypothetic building with improved performance with respect to La Clota. Main tools used are energy dynamic simulation and, when necessary, CFD analysis in order to go into the effect of specific measures in depth. Accordingly, conclusions about the most effective energy measures are drawn, not only for this particular building, but also for other Mediterranean climate locations
Automated context aware composition of Advanced Telecom Services for environmental early warnings
This paper presents one of the main components of a framework for automated composition of Advanced Telecom Services for environmental early Warnings. The framework, called AUTO, is composed by three main modules: a request processing module that transforms natural language and context information into a planning instance; the automated planning module, based on PELEA, an architecture for planning and execution; and the Service Execution Environment Advance Telecom Services. This paper focuses on the description of the translation of the user request in natural language and his context into planning instances. These planning instances represent service composition tasks based on Automated Planning. The advantages of this approach, like the automatic inclusion of context and user preferences in the composition of services, will be presented. Also, the current implementation will be described and some experimentation will prove the viability of AUTO
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