Effect of dissipative forces on the theory of a single-atom microlaser

We describe a one-atom microlaser involving Poissonian input of atoms with a fixed flight time through an optical resonator. The influence of the cavity reservoir during the interactions of successive individual atoms with the cavity field is included in the analysis. The atomic decay is also considered as it is nonnegligible in the optical regime. During the random intervals of absence of any atom in the cavity, the field evolves under its own dynamics. We discuss the steady-state characteristics of the cavity field. Away from laser threshold, the field can be nonclassical in nature.Comment: 9 pages in LaTex; 3 PS figure

HuR protein attenuates miRNA-mediated repression by promoting miRISC dissociation from the target RNA

The microRNA (miRNA)-mediated repression of protein synthesis in mammalian cells is a reversible process. Target mRNAs with regulatory AU-rich elements (AREs) in their 3′-untranslated regions (3′-UTR) can be relieved of miRNA repression under cellular stress in a process involving the embryonic lethal and altered vision family ARE-binding protein HuR. The HuR-mediated derepression occurred even when AREs were positioned at a considerable distance from the miRNA sites raising questions about the mechanism of HuR action. Here, we show that the relief of miRNA-mediated repression involving HuR can be recapitulated in different in vitro systems in the absence of stress, indicating that HuR alone is sufficient to relieve the miRNA repression upon binding to RNA ARE. Using in vitro assays with purified miRISC and recombinant HuR and its mutants, we show that HuR, likely by its property to oligomerize along RNA, leads to the dissociation of miRISC from target RNA even when miRISC and HuR binding sites are positioned at a distance. Further, we demonstrate that HuR association with AREs can also inhibit miRNA-mediated deadenylation of mRNA in the Krebs-2 ascites extract, in a manner likewise depending on the potential of HuR to oligomeriz

Synthesis and Properties of High Tilted Antiferroelectric Esters with Partially Fluorinated Alkoxyalkoxy Terminal Chains

Novel chiral esters with partially fluorinated alkoxyalkoxy terminal chains are described. Their phase transition temperatures, enthalpies, and electrooptical properties are reported. A helical pitch in pure compounds and their mixtures based on selective reflection of light is also characterized

Photon trains and lasing : The periodically pumped quantum dot

We propose to pump semiconductor quantum dots with surface acoustic waves which deliver an alternating periodic sequence of electrons and holes. In combination with a good optical cavity such regular pumping could entail anti-bunching and sub-Poissonian photon statistics. In the bad-cavity limit a train of equally spaced photons would arise.Comment: RevTex, 5 pages, 1 figur

Dynamics, correlations and phases of the micromaser

The micromaser possesses a variety of dynamical phase transitions parametrized by the flux of atoms and the time-of-flight of the atom within the cavity. We discuss how these phases may be revealed to an observer outside the cavity using the long-time correlation length in the atomic beam. Some of the phase transitions are not reflected in the average excitation level of the outgoing atom, which is the commonly used observable. The correlation length is directly related to the leading eigenvalue of the time evolution operator, which we study in order to elucidate the phase structure. We find that as a function of the time-of-flight the transition from the thermal to the maser phase is characterized by a sharp peak in the correlation length. For longer times-of-flight there is a transition to a phase where the correlation length grows exponentially with the flux. We present a detailed numerical and analytical treatment of the different phases and discuss the physics behind them.Comment: 60 pages, 18 figure files, Latex + \special{} for the figures, (some redundant figures are eliminated and others are changed

Squeezing generation and revivals in a cavity-ion system in contact with a reservoir

We consider a system consisting of a single two-level ion in a harmonic trap, which is localized inside a non-ideal optical cavity at zero temperature and subjected to the action of two external lasers. We are able to obtain an analytical solution for the total density operator of the system and show that squeezing in the motion of the ion and in the cavity field is generated. We also show that complete revivals of the states of the motion of the ion and of the cavity field occur periodically.Comment: 9 pages, 3 figure

Enhancing Acceleration Radiation from Ground-State Atoms via Cavity Quantum Electrodynamics

When ground state atoms are accelerated through a high Q microwave cavity, radiation is produced with an intensity which can exceed the intensity of Unruh acceleration radiation in free space by many orders of magnitude. The cavity field at steady state is described by a thermal density matrix under most conditions. However, under some conditions gain is possible, and when the atoms are injected in a regular fashion, the radiation can be produced in a squeezed state

Pre-exposure Prophylaxis Implementation in Family Planning Services Across the Southern United States: Findings from a Survey Among Staff, Providers and Administrators Working in Title X-Funded Clinics

To improve women's access to pre-exposure prophylaxis (PrEP) in family planning (FP) clinics, we examined readiness to provide PrEP, and barriers and facilitators at the clinic level to integrate PrEP services into Title X-funded FP clinics across the Southern US. Title X-funded FP clinics across DHHS regions III (Mid-Atlantic), IV (Southeast), and VI (Southwest), comprising the Southern US. From February to June, 2018, we conducted a web-based, geographically targeted survey of medical staff, providers and administrators of Title X-funded FP clinics in DHHS regions III (Mid-Atlantic), IV (Southeast), and VI (Southwest). Survey items were developed using the Consolidated Framework for Implementation Research to assess constructs relevant to PrEP implementation. One-fifth of 283 unique Title X clinics across the South provided PrEP. Readiness for PrEP implementation was positively associated with a climate supportive of HIV prevention, leadership engagement, and availability of resources, and negatively associated with providers holding negative attitudes about PrEP's suitability for FP. The Title X FP network is a vital source of sexual health care for millions of individuals across the US. Clinic-level barriers to providing PrEP must be addressed to expand onsite PrEP delivery in Title X FP clinics in the Southern US