7,830 research outputs found
Probability tilting of compensated fragmentations
Fragmentation processes are part of a broad class of models describing the
evolution of a system of particles which split apart at random. These models
are widely used in biology, materials science and nuclear physics, and their
asymptotic behaviour at large times is interesting both mathematically and
practically. The spine decomposition is a key tool in its study. In this work,
we consider the class of compensated fragmentations, or homogeneous
growth-fragmentations, recently defined by Bertoin. We give a complete spine
decomposition of these processes in terms of a L\'evy process with immigration,
and apply our result to study the asymptotic properties of the derivative
martingale.Comment: 41 pages, 1 figure. This revised version improves the conditions in
Theorem 6.
Coexistence of strong nematic and superconducting correlations in a two-dimensional Hubbard model
Using a dynamic cluster quantum Monte Carlo approximation, we study a
two-dimensional Hubbard model with a small orthorhombic distortion in the
nearest neighbor hopping integrals. We find a large nematic response in the
low-frequency single-particle scattering rate which develops with decreasing
temperature and doping as the pseudogap region is entered. At the same time,
the d-wave superconducting gap function develops an s-wave component and its
amplitude becomes anisotropic. The strength of the pairing correlations,
however, is found to be unaffected by the strong anisotropy, indicating that
d-wave superconductivity can coexist with strong nematicity in the system.Comment: 4 pages, 4 figures, published as PRB 84, 220506(R) (2011
Complex quantum network model of energy transfer in photosynthetic complexes
The quantum network model with real variables is usually used to describe the
excitation energy transfer (EET) in the Fenna-Matthews-Olson(FMO) complexes. In
this paper we add the quantum phase factors to the hopping terms and find that
the quantum phase factors play an important role in the EET. The quantum phase
factors allow us to consider the space structure of the pigments. It is found
that phase coherence within the complexes would allow quantum interference to
affect the dynamics of the EET. There exist some optimal phase regions where
the transfer efficiency takes its maxima, which indicates that when the
pigments are optimally spaced, the exciton can pass through the FMO with
perfect efficiency. Moreover, the optimal phase regions almost do not change
with the environments. In addition, we find that the phase factors are useful
in the EET just in the case of multiple-pathway. Therefore, we demonstrate
that, the quantum phases may bring the other two factors, the optimal space of
the pigments and multiple-pathway, together to contribute the EET in
photosynthetic complexes with perfect efficiency.Comment: 8 pages, 9 figure
Permeability and injectivity improvement in CO2 enhanced coalbed methane recovery : thermal stimulation of the near wellbore region
Non peer reviewedPublisher PD
Monotonicity Results for Arithmetic Means of Concave and Convex Functions
By majorization approaches, some known results on monotonicity
of the arithmetic means of convex and concave functions are proved and
generalized once again
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CROWDSOURCING BASED MICRO NAVIGATION SYSTEM FOR VISUALLY IMPAIRED
Mobility and safety are primary concerns for blind and visually impaired (BVI) users when navigating in unfamiliar environments. Typically, a sighted person can locate a place of interest if they are provided guidance while approaching within a few meters of the location. However, this resolution of guidance is often insufficient for blind travelers. In this thesis, we propose a crowdsourcing based micro navigation system for BVI users in both indoor and outdoor environments. To achieve this goal, our system includes three parts: crowdsourcing reports generated by volunteers using the volunteer application, landmarks validation performed by the system administrator using the admin application, and the BVI user navigation obtained through the BVI user application. In addition, we provide accessible audio navigation for indoor and outdoor environments required to deliver real time step by step landmark information to BVI users.
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