208 research outputs found
Lexical Portrait of an Oral Story: a Corpus Study of Speech of Two Generations of Native Speakers of Russian
The article is devoted to the quantitative and statistical analysis of the vocabulary of the oral stories corpus based on pictures. The subjects were 42 people, monolingual native speakers of the Russian (representatives of 15 families). The purpose of the study is to identify and describe the lexical parameters that distinguish the oral stories of representatives of different generations. An attempt is made to consider the connection of these parameters with the formation of native speakers’ ideas about the lexical structure of the narrative. The following results are obtained. The nature of the stimulus material ensured an approximately equal degree of complexity in the texts of both groups, although the volume of the parents’ active vocabulary significantly exceeded the volume of the children’s vocabulary. At the level of individual texts, both groups use equally diverse vocabulary per unit of text volume. In the children’s stories, the main “plot” vocabulary is quite heterogeneous, while the parents tend to lexical unification of the narrative. In the texts of both groups, local reference and direction of movement are expressed in the same way, which indicates their “basic” narrative function, which does not depend on the age of the subjects. The stories of the parents are also unified in terms of vocabulary, showing the logical structure of the narrative and different types of semantic relations in the text
Controlling Purity, Indistinguishability and Quantum Yield of Incoherently Pumped Two-Level System by Spectral Filters
Dephasing processes significantly impact the performance of deterministic
single-photon sources. Dephasing broadens the spectral line and suppresses the
indistinguishability of the emitted photons, which is undesirable for many
applications, primarily for quantum computing. We consider a light emitted by a
two-level system with a pulsed incoherent pump in the presence of the spectral
filter. The spectral filter allows control of the second-order autocorrelation
function, indistinguishability, and quantum yield. We show that narrow spectral
filters can increase the indistinguishability of the emitted light while
undermining the quantum yield. The influence of the spectral filter on the
second-order correlation function depends on the duration of the pump. When the
pumping pulse is long compared to the lifetime of the two-level system, the
narrow spectral filters lead to a rapid increase in the second-order
autocorrelation function. In this limit, the statistics of the light from the
two-level system inherit the statistics of the incoherent pump. In the case of
the short duration of the pump pulse, it is possible to preserve single-photon
properties to some degree for the sub-lifetime width of the spectral filter.
Moreover, when the light emitted by the single-photon source is used to control
a quantum system, e.g., cavity, the single-photon properties of the light
manifest themselves differently, depending on the response time of the quantum
system. In particular, in the case of long response time, the spectral filter
with sub-lifetime width can provide the near-zero second-order autocorrelation
function
Synthesis and Characterization of Organic Impurities in Bortezomib Anhydride Produced by a Convergent Technology
A profile of impurities in bortezomib anhydride, produced by a recently developed convergent technology, has been characterized. HPLC-MS analysis of the drug essence revealed three impurities: an epimer of bortezomib, resulting from partial racemization of l-phenylalanine’s stereogenic center during the chemical synthesis, and two epimeric products of oxidative degradation of bortezomib, in which boron is replaced by the OH group. The impurities were obtained by chemical synthesis and characterized by physical methods
Collapses and revivals of polarization and radiation intensity induced by strong exciton-vibron coupling
Recently, systems with strong coupling between electronic and vibrational
degrees of freedom attract a great attention. In this work, we consider the
transient dynamics of the system consisting of strongly coupled vibron and
exciton driven by external monochromatic field. We show that under coherent
pumping, polarization of exciton exhibits complex quantum dynamics which can be
divided into three stages. At the first stage, exciton oscillations at its
eigenfrequency relax due to the transition to set of shifted Fock states of
vibrons. We demonstrate that these shifted Fock states play the role of an
effective reservoir for the excited exciton state. The time of relaxation to
this reservoir depends on exciton-vibron coupling. At the second stage,
excitation, transferred to the reservoir of the vibronic shifted states at the
first stage, returns into electronic degrees of freedom and revival of
oscillations at exciton eigenfrequency appears. Thus, the dynamics of molecular
polarization exhibit collapses and revivals. At the final stage, these
collapses and revivals dissipate and polarization exhibits Rayleigh response at
the frequency of the external field. Discovered collapses and revivals manifest
in radiation spectrum as multiple splitting of the spectral line near the
exciton transition frequency
Effect of Complexes of Cobalt With Aminoacids on the Replication of Herpes Simplex Virus Type 1 (HSV-1)
Cobalt, being essential metal, influences different physiological and enzymatic functions. As cobalt
does not accumulate in the body, Co-compounds have relatively low toxicity. The aim of the present
study is the effect of complexes of Co(II) with aminoacids - lysine, arginine, histidine and serine on
HSV-1 replication. No effect of [O2Co(his)4].nH2O and [O2Co(arg)2].nH2O on HSV-1 infection in vitro
was found. Both, [O2Co(lys)2].nH2O and [O2Co(ser)2].nH2O suppress the attachement of HSV-1
particles onto target cells and the viral replication as well. Moreover, the properties of the particular
Co-complex (charge, stability, structure) are manifestated by their virucidal effect. Thus,
[O2Co(ser)2].nH2O irreversibly inhibits the infectious activity of free HSV-1 virions, while virucidal
effect of [O2Co(lys)2].nH2O is completely reversible after the 2h of contact
Adjoint master equation for multi-time correlators
The quantum regression theorem is a powerful tool for calculating the
muli-time correlators of operators of open quantum systems which dynamics can
be described in Markovian approximation. It enables to obtain the closed system
of equation for the multi-time correlators. However, the scope of the quantum
regression theorem is limited by a particular time order of the operators in
multi-time correlators and does not include out-of-time-ordered correlators. In
this work, we obtain an adjoint master equation for multi-time correlators that
is applicable to out-of-time-ordered correlators. We show that this equation
can be derived for various approaches to description of the dynamics of open
quantum systems, such as the global or local approach. We show that the adjoint
master equation for multi-time correlators is self-consistent. Namely, the
final equation does not depend on how the operators are grouped inside the
correlator, and it coincides with the quantum regression theorem for the
particular time ordering of the operators.Comment: 11 page
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