1,933 research outputs found
Aharonov-Anandan phase in Lipkin-Meskov-Glick model
In the system of several interacting spins, geometric phases have been
researched intensively.However, the studies are mainly focused on the adiabatic
case (Berry phase), so it is necessary for us to study the non-adiabatic
counterpart (Aharonov and Anandan phase). In this paper, we analyze both the
non-degenerate and degenerate geometric phase of Lipkin-Meskov-Glick type
model, which has many application in Bose-Einstein condensates and entanglement
theory. Furthermore, in order to calculate degenerate geometric phases, the
Floquet theorem and decomposition of operator are generalized. And the general
formula is achieved
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Understanding Sources of Defects in Polyimide Films Using Aerosol Based Printing
A study of the sources of defects in films of commercially available polyamic acid
fabricated using aerosol based printing was carried out. Printing was conducted using a Sono-Tek spray nozzle on multi-modular Direct Write Additive Manufacturing System. The driving
force behind this work stemmed from the need to form smooth, defect free films to be used in
electronic components. While numerous process conditions give rise to defects such as the
obvious substrate cleanliness, efforts here focused on the more subtle conditions such as
deposition temperature, deposition speed, nozzle height from the substrate and cure temperature.
The results of this study led to the identification of the most critical source of defects and to a set
of optimal process conditions in the printing of polyimide films using aerosol based printing.Mechanical Engineerin
Hybridization in bottlenose dolphins—A case study of Tursiops aduncus × T. truncatus hybrids and successful backcross hybridization events
The bottlenose dolphin, genus Tursiops is one of the best studied of all the Cetacea with a minimum of two species widely recognised. Common bottlenose dolphins (T. truncatus), are the cetacean species most frequently held in captivity and are known to hybridize with species from at least 6 different genera. In this study, we document several intra-generic hybridization events between T. truncatus and T. aduncus held in captivity. We demonstrate that the F1 hybrids are fertile and can backcross producing apparently healthy offspring, thereby showing introgressive inter-specific hybridization within the genus. We document that female F1 hybrids can reach sexual maturity at 4 yr and 3 mo of age, and can become pregnant and give birth before being fully weaned. The information presented has implications for understanding hybrid reticulation among cetacean species and practical implications for captive facilities housing either Tursiops species or hybrids thereof
Geometric Aspects of D-branes and T-duality
We explore the differential geometry of T-duality and D-branes. Because
D-branes and RR-fields are properly described via K-theory, we discuss the
(differential) K-theoretic generalization of T-duality and its application to
the coupling of D-branes to RR-fields. This leads to a puzzle involving the
transformation of the A-roof genera in the coupling.Comment: 26 pages, JHEP format, uses dcpic.sty; v2: references added, v3:
minor change
Recoil-Induced-Resonances in Nonlinear, Ground-State, Pump-Probe Spectroscopy
A theory of pump-probe spectroscopy is developed in which optical fields
drive two-photon Raman transitions between ground states of an ensemble of
three-level atoms. Effects related to the recoil the atoms undergo
as a result of their interactions with the fields are fully accounted for in
this theory. The linear absorption coefficient of a weak probe field in the
presence of two pump fields of arbitrary strength is calculated. For subrecoil
cooled atoms, the spectrum consists of eight absorption lines and eight
emission lines. In the limit that , where and
are the Rabi frequencies of the two pump fields, one recovers the
absorption spectrum for a probe field interacting with an effective two-level
atom in the presence of a single pump field. However when , new interference effects arise that allow one to selectively turn on
and off some of these recoil induced resonances.Comment: 30 pages, 8 figures. RevTex. Submitted to Phys. Rev. A, Revised
versio
String Field Theory Projectors for Fermions of Integral Weight
The interaction vertex for a fermionic first order system of weights (1,0)
such as the twisted bc-system, the fermionic part of N=2 string field theory
and the auxiliary \eta\xi system of N=1 strings is formulated in the Moyal
basis. In this basis, the Neumann matrices are diagonal; as usual, the
eigenvectors are labeled by \kappa\in\R. Oscillators constructed from these
eigenvectors make up two Clifford algebras for each nonzero value of \kappa.
Using a generalization of the Moyal-Weyl map to the fermionic case, we classify
all projectors of the star-algebra which factorize into projectors for each
\kappa-subspace. At least for the case of squeezed states we recover the full
set of bosonic projectors with this property. Among the subclass of ghost
number-homogeneous squeezed state projectors, we find a single class of
BPZ-real states parametrized by one (nearly) arbitrary function of \kappa. This
class is shown to contain the generalized butterfly states. Furthermore, we
elaborate on sufficient and necessary conditions which have to be fulfilled by
our projectors in order to constitute surface states. As a byproduct we find
that the full star product of N=2 string field theory translates into a
canonically normalized continuous tensor product of Moyal-Weyl products up to
an overall normalization. The divergent factors arising from the translation to
the continuous basis cancel between bosons and fermions in any even dimension.Comment: LaTeX, 1+23 pages, minor improvements, references adde
NONDESTRUCTIVE EXAMINATION OF FUEL PLATES FOR THE RERTR FUEL DEVELOPMENT EXPERIMENTS
Nuclear fuel is the core component of reactors that is used to produce the neutron flux required for irradiation research purposes as well as commercial power generation. The development of nuclear fuels with low enrichments of uranium is a major endeavor of the RERTR program. In the development of these fuels, the RERTR program uses nondestructive examination (NDE) techniques for the purpose of determining the properties of nuclear fuel plate experiments without imparting damage or altering the fuel specimens before they are irradiated in a reactor. The vast range of properties and information about the fuel plates that can be characterized using NDE makes them highly useful for quality assurance and for analyses used in modeling the behavior of the fuel while undergoing irradiation. NDE is also particularly useful for creating a control group for post-irradiation examination comparison. The two major categories of NDE discussed in this paper are X-ray radiography and ultrasonic testing (UT) inspection/evaluation. The radiographic scans are used for the characterization of fuel meat density and homogeneity as well as the determination of fuel location within the cladding. The UT scans are able to characterize indications such as voids, delaminations, inclusions, and other abnormalities in the fuel plates which are generally referred to as debonds as well as to determine the thickness of the cladding using ultrasonic acoustic microscopy methods. Additionally, the UT techniques are now also being applied to in-canal interim examination of fuel experiments undergoing irradiation and the mapping of the fuel plate surface profile to determine fuel swelling. The methods used to carry out these NDE techniques, as well as how they operate and function, are described along with a description of which properties are characterized
Normalization anomalies in level truncation calculations
We test oscillator level truncation regularization in string field theory by
calculating descent relations among vertices, or equivalently, the overlap of
wedge states. We repeat the calculation using bosonic, as well as fermionic
ghosts, where in the bosonic case we do the calculation both in the discrete
and in the continuous basis. We also calculate analogous expressions in field
level truncation. Each calculation gives a different result. We point out to
the source of these differences and in the bosonic ghost case we pinpoint the
origin of the difference between the discrete and continuous basis
calculations. The conclusion is that level truncation regularization cannot be
trusted in calculations involving normalization of singular states, such as
wedge states, rank-one squeezed state projectors and string vertices.Comment: 1+20 pages, 6 figures. v2: Ref. added, typos correcte
Multidimensional continued fractions, dynamical renormalization and KAM theory
The disadvantage of `traditional' multidimensional continued fraction
algorithms is that it is not known whether they provide simultaneous rational
approximations for generic vectors. Following ideas of Dani, Lagarias and
Kleinbock-Margulis we describe a simple algorithm based on the dynamics of
flows on the homogeneous space SL(2,Z)\SL(2,R) (the space of lattices of
covolume one) that indeed yields best possible approximations to any irrational
vector. The algorithm is ideally suited for a number of dynamical applications
that involve small divisor problems. We explicitely construct renormalization
schemes for (a) the linearization of vector fields on tori of arbitrary
dimension and (b) the construction of invariant tori for Hamiltonian systems.Comment: 51 page
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