12 research outputs found
Gamow Shell Model Description of Weakly Bound Nuclei and Unbound Nuclear States
We present the study of weakly bound, neutron-rich nuclei using the nuclear
shell model employing the complex Berggren ensemble representing the bound
single-particle states, unbound Gamow states, and the non-resonant continuum.
In the proposed Gamow Shell Model, the Hamiltonian consists of a one-body
finite depth (Woods-Saxon) potential and a residual two-body interaction. We
discuss the basic ingredients of the Gamow Shell Model. The formalism is
illustrated by calculations involving {\it several} valence neutrons outside
the double-magic core: He and O.Comment: 19 pages, 20 encapsulated PostScript figure
Probabilistic Interpretation of Resonant States
We provide probabilistic interpretation of resonant states. This we do by
showing that the integral of the modulus square of resonance wave functions
(i.e., the conventional norm) over a properly expanding spatial domain is
independent of time, and therefore leads to probability conservation. This is
in contrast with the conventional employment of a bi-orthogonal basis that
precludes probabilistic interpretation, since wave functions of resonant states
diverge exponentially in space. On the other hand, resonant states decay
exponentially in time, because momentum leaks out of the central scattering
area. This momentum leakage is also the reason for the spatial exponential
divergence of resonant state. It is by combining the opposite temporal and
spatial behaviors of resonant states that we arrive at our probabilistic
interpretation of these states. The physical need to normalize resonant wave
functions over an expanding spatial domain arises because particles leak out of
the region which contains the potential range and escape to infinity, and one
has to include them in the total count of particle number.Comment: 11 pages, 5 figures, to appear in Pramana Journal of Physics as an
article in the proceedings of Homi Bhabha Centenary Conference on
Non-Hermitian Hamiltonians in Quantum Physics PHHQP VIII; this version are
with added references as well as some rewording after reviewer's suggestion
Genome Sequence and Analysis of a Propionibacterium acnes Bacteriophage▿ †
Cutaneous propionibacteria are important commensals of human skin and are implicated in a wide range of opportunistic infections. Propionibacterium acnes is also associated with inflammatory acne vulgaris. Bacteriophage PA6 is the first phage of P. acnes to be sequenced and demonstrates a high degree of similarity to many mycobacteriophages both morphologically and genetically. PA6 possesses an icosahedreal head and long noncontractile tail characteristic of the Siphoviridae. The overall genome organization of PA6 resembled that of the temperate mycobacteriophages, although the genome was much smaller, 29,739 bp (48 predicted genes), compared to, for example, 50,550 bp (86 predicted genes) for the Bxb1 genome. PA6 infected only P. acnes and produced clear plaques with turbid centers, but it lacked any obvious genes for lysogeny. The host range of PA6 was restricted to P. acnes, but the phage was able to infect and lyse all P. acnes isolates tested. Sequencing of the PA6 genome makes an important contribution to the study of phage evolution and propionibacterial genetics