33 research outputs found
Dynamics of entropy and nonclassical properties of the state of a -type three-level atom interacting with a single-mode cavity field with intensity-dependent coupling in a Kerr medium
In this paper, we study the interaction between a three-level atom and a
quantized single-mode field with intensity-dependent coupling in a Kerr medium.
The three-level atom is considered to be in a -type configuration.
Under particular initial conditions, which may be prepared for the atom and
the field, the dynamical state vector of the entire system will be explicitly
obtained, for arbitrary nonlinearity function associated to any physical
system.
Then, after evaluating the variation of the field entropy against time, we
will investigate the quantum statistics as well as some of the nonclassical
properties of the introduced state. During our calculations we investigate the
effects of intensity-dependent coupling, Kerr medium and detuning parameters on
the depth and domain of the nonclassicality features of the atom-field state
vector. Finally, we compare our obtained results with those of -type
three-level atoms.Comment: 18 pages, 7 Figure
Superpositions of the dual family of nonlinear coherent states and their non-classical properties
Nonlinear coherent states (CSs) and their {\it dual families} were introduced
recently. In this paper we want to obtain their superposition and investigate
their non-classical properties such as antibunching effect, quadrature
squeezing and amplitude squared squeezing. For this purpose two types of
superposition are considered. In the first type we neglect the normalization
factors of the two components of the dual pair, superpose them and then we
normalize the obtained states, while in the second type we superpose the two
normalized components and then again normalize the resultant states. As a
physical realization, the formalism will then be applied to a special physical
system with known nonlinearity function, i.e., Hydrogen-like spectrum. We
continue with the (first type of) superposition of the dual pair of
Gazeau-Klauder coherent states (GKCSs) as temporally stable CSs. An application
of the proposal will be given by employing the P\"oschl-Teller potential
system. The numerical results are presented and discussed in detail, showing
the effects of this special quantum interference.Comment: 19 pages, 18 figures, Accpeted for Publication in Optics
Communications, 201
The Construction of Some Important Classes of Generalized Coherent states: The Nonlinear Coherent States Method
Considering some important classes of generalized coherent states known in
literature, we demonstrated that all of them can be created via conventional
fashion, i.e. the "lowering operator eigen-state" and the "displacement
operator" techniques using the {\it "nonlinear coherent states"} approach. As a
result we obtained a {\it "unified method"} to construct a large class of
coherent states which already have been introduced by different prescriptions.Comment: 17pages, The section 7 in last version is revised, Some references
are adde
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field