986 research outputs found
Photon-energy dissipation caused by an external electric circuit in "virtual" photo-excitation processes
We consider generation of an electrical pulse by an optical pulse in the
``virtual excitation'' regime. The electronic system, which is any
electro-optic material including a quantum well structure biased by a dc
electric field, is assumed to be coupled to an external circuit. It is found
that the photon frequency is subject to an extra red shift in addition to the
usual self-phase modulation, whereas the photon number is conserved. The Joule
energy consumed in the external circuit is supplied only from the extra red
shift.Comment: 4 pages, 1 fugur
F and D Values with Explicit Flavor Symmetry Breaking and \Delta s Contents of Nucleons
We propose a new model for describing baryon semi-leptonic decays for
estimating and values with explicit breaking effects of both SU(3) and
SU(2) flavor symmetry, where all possible SU(3) and SU(2) breaking effects are
induced from an effective interaction. An overall fit including the weak
magnetism form factor yields and with
d.o.f. with and . The spin content of strange quarks is estimated from the
obtained values and , and the nucleon spin problem is re-examined.
Furthermore, the unmeasured values of and for other hyperon
semi-leptonic decays are predicted from this new formula.Comment: 15 pages, 1 figure, final version to appear in PR
Upstream activation element of the PH03 gene encoding for thiamine-repressible acid phosphatase in Saccharomyces cerevisiae
AbstractThe PH03 gene of Saccharomyces cerevisiae encodes thiamine-repressible acid phosphatase and requires the positively acting regulatory protein TH12 for its expression. Deletion analysis of the 5′-flanking region of PH03 gene revealed that an activating region located at nucleotide position −234 to −215 relative to the translation initiation codon is required for the expression and sensitivity to thiamine. A chemically synthesized DNA fragment covering −234 to −215 showed a significant level of expression when inserted in front of the PH03 promoter lacking the activating region. Electrophoretic mobility shift assay demonstrated the presence of proteins that bound to the above DNA fragment in the nuclear extract from cells grown in thiamine-free medium. These findings suggested that this region between −234 and −215 acts as an upstream activation element of the PH03 gene that can interact with regulatory proteins
Generalised Decision Level Ensemble Method for Classifying Multi-media Data
In recent decades, multimedia data have been commonly generated and used in various domains, such as in healthcare and social media due to their ability of capturing rich information. But as they are unstructured and separated, how to fuse and integrate multimedia datasets and then learn from them eectively have been a main challenge to machine learning. We present a novel generalised decision level ensemble method (GDLEM) that combines the multimedia datasets at decision level. After extracting features from each of multimedia datasets separately, the method trains models independently on each media dataset and then employs a generalised selection function to choose the appropriate models to construct a heterogeneous ensemble. The selection function is dened as a weighted combination of two criteria: the accuracy of individual models and the diversity among the models. The framework is tested on multimedia data and compared with other heterogeneous ensembles. The results show that the GDLEM is more exible and eective
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Hyperbolic Ordinal Embedding
Given ordinal relations such as the object i is more similar to j than k is to l, ordinal embedding is to embed these objects into a low-dimensional space with all ordinal constraints
preserved. Although existing approaches have preserved ordinal relations in Euclidean
space, whether Euclidean space is compatible with true data structure is largely ignored,
although it is essential to effective embedding. Since real data often exhibit hierarchical
structure, it is hard for Euclidean space approaches to achieve effective embeddings in low
dimensionality, which incurs high computational complexity or overfitting. In this paper we
propose a novel hyperbolic ordinal embedding (HOE) method to embed objects in hyperbolic space. Due to the hierarchy-friendly property of hyperbolic space, HOE can effectively
capture the hierarchy to achieve embeddings in an extremely low-dimensional space. We
have not only theoretically proved the superiority of hyperbolic space and the limitations
of Euclidean space for embedding hierarchical data, but also experimentally demonstrated
that HOE significantly outperforms Euclidean-based methods
Quantum Langevin equations for semiconductor light-emitting devices and the photon statistics at a low-injection level
From the microscopic quantum Langevin equations (QLEs) we derive the
effective semiconductor QLEs and the associated noise correlations which are
valid at a low-injection level and in real devices. Applying the semiconductor
QLEs to semiconductor light-emitting devices (LEDs), we obtain a new formula
for the Fano factor of photons which gives the photon-number statistics as a
function of the pump statistics and several parameters of LEDs. Key ingredients
are non-radiative processes, carrier-number dependence of the radiative and
non-radiative lifetimes, and multimodeness of LEDs. The formula is applicable
to the actual cases where the quantum efficiency differs from the
differential quantum efficiency , whereas previous theories
implicitly assumed . It is also applicable to the cases when
photons in each mode of the cavity are emitted and/or detected inhomogeneously.
When at a running point, in particular, our formula predicts
that even a Poissonian pump can produce sub-Poissonian light. This mechanism
for generation of sub-Poissonian light is completely different from those of
previous theories, which assumed sub-Poissonian statistics for the current
injected into the active layers of LEDs. Our results agree with recent
experiments. We also discuss frequency dependence of the photon statistics.Comment: 10 pages, 8 figure
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