Electron Microscope Studies of Heteroduplex DNA from a Deletion Mutant of Bacteriophage phi X-174

A population of double-stranded replicative form of DNA molecules from bacteriophage phi X-174 carrying a deletion of about 9% of the wild-type DNA has been discovered in a sample cultivated under conditions where the phage lysozyme gene is nonessential. The structures of deleted monomers, dimers, and trimers were studied by the electron microscope heteroduplex method. The dimers and trimers are head-to-tail repeats of the deleted monomers. Some interesting examples of the dynamical phenomenon of branch migration in vitro have been observed in heteroduplexes of deleted dimer and trimer strands with undeleted monomer viral strands from the wild-type phage

A quasi-time-dependent radiative transfer model of OH104.9+2.4

We investigate the pulsation-phase dependent properties of the circumstellar dust shell (CDS) of the OH/IR star OH104.9+2.4 based on radiative transfer modeling (RTM) using the code DUSTY. Our previous study concerning simultaneous modeling of the spectral energy distribution (SED) and near-infrared (NIR) visibilities (Riechers et al. 2004) has now been extended by means of a more detailed analysis of the pulsation-phase dependence of the model parameters of OH104.9+2.4. In order to investigate the temporal variation in the spatial structure of the CDS, additional NIR speckle interferometric observations in the K' band were carried out with the 6 m telescope of the Special Astrophysical Observatory (SAO). At a wavelength of 2.12 micron the diffraction-limited resolution of 74 mas was attained. Several key parameters of our previous best-fitting model had to be adjusted in order to be consistent with the newly extended amount of observational data. It was found that a simple rescaling of the bolometric flux F_bol is not sufficient to take the variability of the source into account, as the change in optical depth over a full pulsation cycle is rather high. On the other hand, the impact of a change in effective temperature T_eff on SED and visibility is rather small. However, observations, as well as models for other AGB stars, show the necessity of including a variation of T_eff with pulsation phase in the radiative transfer models. Therefore, our new best-fitting model accounts for these changes.Comment: 7 pages, including 5 postscript figures and 3 tables. Published in Astronomy and Astrophysics. (v1: accepted version; v2: published version, minor grammatical changes

Observation and interpretation of motional sideband asymmetry in a quantum electro-mechanical device

Quantum electro-mechanical systems offer a unique opportunity to probe quantum noise properties in macroscopic devices, properties which ultimately stem from the Heisenberg Uncertainty Principle. A simple example of this is expected to occur in a microwave parametric transducer, where mechanical motion generates motional sidebands corresponding to the up and down frequency-conversion of microwave photons. Due to quantum vacuum noise, the rates of these processes are expected to be unequal. We measure this fundamental imbalance in a microwave transducer coupled to a radio-frequency mechanical mode, cooled near the ground state of motion. We also discuss the subtle origin of this imbalance: depending on the measurement scheme, the imbalance is most naturally attributed to the quantum fluctuations of either the mechanical mode or of the electromagnetic field

Exploring the Oxygen Order in Hg-1223 and Hg-1201 by 199Hg MAS NMR

We demonstrate the use of a high-resolution solid-state fast (45 kHz) magic angle spinning (MAS) NMR for mapping the oxygen distribution in Hg-based cuprate superconductors. We identify observed three peaks in 199Hg spectrum as belonging to the different chemical environments in the HgO? layer with no oxygen neighbors, single oxygen neighbor, and two oxygen neighbors. We discuss observed differences between Hg-1201 and Hg-1223 materials.Comment: 4 pages, 2 figures included. Submitted to NATO Advanced Research Workshop Proceedings (Miami January 2004

Quantum squeezing of motion in a mechanical resonator

As a result of the quantum, wave-like nature of the physical world, a harmonic oscillator can never be completely at rest. Even in the quantum ground state, its position will always have fluctuations, called the zero-point motion. Although the zero-point fluctuations are unavoidable, they can be manipulated. In this work, using microwave frequency radiation pressure, we both prepare a micron-scale mechanical system in a state near the quantum ground state and then manipulate its thermal fluctuations to produce a stationary, quadrature-squeezed state. We deduce that the variance of one motional quadrature is 0.80 times the zero-point level, or 1 dB of sub-zero-point squeezing. This work is relevant to the quantum engineering of states of matter at large length scales, the study of decoherence of large quantum systems, and for the realization of ultra-sensitive sensing of force and motion

Incidental finding of lymphoma after septoplasty.

IntroductionSeptoplasty, or surgical correction of the deviated septum, is an elective, routinely performed rhinologic procedure to address nasal airway obstruction. In many cases, resected septal cartilage and bone fragments are sent for pathologic review, although there is no consensus on this practice. We reported two cases of incidentally diagnosed lymphoma after elective septoplasty and discussed clinical presentation, diagnosis, and management.MethodsRetrospective chart review of two patients who underwent septoplasty at a tertiary academic medical center and found to have incidental lymphoma based on histopathology.ResultsTwo patients who underwent septoplasty had an incidental diagnosis of lymphoma on pathologic analysis. One patient was noted to have an S-shaped septal deviation that produced bilateral nasal obstruction. She underwent a difficult septoplasty, in which the mucoperichondrial flap was firmly adherent to the underlying septum and bone. Final pathology demonstrated diffuse large B-cell lymphoma. She was treated with chemoradiation and remained free of disease at 59 months. The other patient had a history of nasal trauma, which produced left septal deviation. He underwent an uncomplicated septoplasty, with pathology that demonstrated low-grade B-cell lymphoma. Because there was no evidence of active disease, the decision was made to not treat and to observe the patient clinically.ConclusionsThis is the first reported series of septal lymphoma incidentally diagnosed on routine septoplasty. Although histopathologic review of specimens from routine nasal and sinus surgery is not routinely performed, this report highlighted the importance of this process, on a case-by-case basis, in detecting unexpected malignancies that otherwise were clinically silent

Mechanically Detecting and Avoiding the Quantum Fluctuations of a Microwave Field

During the theoretical investigation of the ultimate sensitivity of gravitational wave detectors through the 1970's and '80's, it was debated whether quantum fluctuations of the light field used for detection, also known as photon shot noise, would ultimately produce a force noise which would disturb the detector and limit the sensitivity. Carlton Caves famously answered this question with "They do." With this understanding came ideas how to avoid this limitation by giving up complete knowledge of the detector's motion. In these back-action evading (BAE) or quantum non-demolition (QND) schemes, one manipulates the required quantum measurement back-action by placing it into a component of the motion which is unobserved and dynamically isolated. Using a superconducting, electro-mechanical device, we realize a sensitive measurement of a single motional quadrature with imprecision below the zero-point fluctuations of motion, detect both the classical and quantum measurement back-action, and demonstrate BAE avoiding the quantum back-action from the microwave photons by 9 dB. Further improvements of these techniques are expected to provide a practical route to manipulate and prepare a squeezed state of motion with mechanical fluctuations below the quantum zero-point level, which is of interest both fundamentally and for the detection of very weak forces