Space station stabilization and control study Final engineering report

Simulation of stabilization and control for spinning, manned space station to provide artificial gravity station environmen

Oblique ion collection in the drift-approximation: how magnetized Mach-probes really work

The anisotropic fluid equations governing a frictionless obliquely-flowing plasma around an essentially arbitrarily shaped three-dimensional ion-absorbing object in a strong magnetic field are solved analytically in the quasi-neutral drift-approximation, neglecting parallel temperature gradients. The effects of transverse displacements traversing the magnetic presheath are also quantified. It is shown that the parallel collection flux density dependence upon external Mach-number is $n_\infty c_s \exp[-1 -(M_{\parallel\infty}- M_\perp\cot\theta)]$ where $\theta$ is the angle (in the plane of field and drift velocity) of the object-surface to the magnetic-field and $M_{\parallel\infty}$ is the external parallel flow. The perpendicular drift, \M_\perp, appearing here consists of the external \E\wedge\B drift plus a weighted sum of the ion and electron electron diamagnetic drifts that depends upon the total angle of the surface to the magnetic field. It is that somewhat counter-intuitive combination that an oblique (transverse) Mach probe experiment measures.Comment: Revised version following refereeing for Physics of Plasma

Stillbirth and intrauterine fetal death:role of routine histopathological placental findings to determine cause of death

OBJECTIVES: Placental abnormalities are a common cause of death in stillbirth, ranking second only to unexplained deaths, though there is wide variation in the proportion attributed to placental disease. In clinical practice, interpretation of the significance of placental findings is difficult, since many placental features in stillbirths overlap with those in live births. Our aim was to examine objectively classified placental findings from a series of > 1000 autopsies following intrauterine death in order to evaluate the role of placental histological examination in determining the cause of death. METHODS: As part of a larger study evaluating several aspects of autopsy findings in intrauterine death, a dedicated database was used to collate antenatal and postmortem examination details for all cases examined between 2005 and 2013 at two tertiary specialist centers in London, UK. Histological findings for placentas were evaluated in relation to the final cause of death. RESULTS: Among 1064 intrauterine deaths, 946 (89%) cases had the placenta submitted for examination as part of the autopsy. Of these, 307 (32%) cases had the cause of death assigned to abnormalities of the placenta, cord or membranes. Around one third of stillbirths (≥ 24 weeks) had some isolated placental histological abnormality identified, many of uncertain significance, a significantly greater proportion than in cases of second-trimester intrauterine fetal demise (P < 0.0001). The cause of death was ascending infection in 176/946 (19%) cases, peaking at 22 weeks' gestation, with significantly more black mothers having ascending infection compared with other ethnicities (P < 0.0001). Maternal vascular malperfusion was the largest category of placental abnormalities in stillbirth, with peak prevalence in the early third trimester. There were 18 (2%) cases with specific histological abnormalities, including chronic histiocytic intervillositis and massive perivillous fibrin deposition. CONCLUSIONS: Placental pathologies represent the largest category of cause of intrauterine death. Placental histological examination is the single most useful component of the autopsy process in this clinical setting. A minority of cases are associated with specific placental pathologies, often with high recurrence rates, that can be diagnosed only on microscopic examination of the placenta. Many deaths remain unexplained, although placental histological lesions may be present which are of uncertain significance. A rigorous, systematic approach to placental pathology research and classification may yield better understanding of the significance of placental findings and reduce the rate of unexplained intrauterine deaths

Adverse Outcome Pathways can drive non-animal approaches for safety assessment

Adverse Outcome Pathways (AOPs) provide an opportunity to develop new and more accurate safety assessment processes for drugs and other chemicals, and may ultimately play an important role in regulatory decision making. Not only can the development and application of AOPs pave the way for the development of improved evidence-based approaches for hazard and risk assessment, there is also the promise of a significant impact on animal welfare, with a reduced reliance on animal-based methods. The establishment of a useable and coherent knowledge framework under which AOPs will be developed and applied has been a first critical step towards realizing this opportunity. This article explores how the development of AOPs under this framework, and their application in practice, could benefit the science and practice of safety assessment, while in parallel stimulating a move away from traditional methods towards an increased acceptance of non-animal approaches. We discuss here the key areas where current, and future initiatives should be focused to enable the translation of AOPs into routine chemical safety assessment, and lasting 3Rs benefits

Electronic temperatures, densities and plasma X-ray emission of a 14.5 GHz Electron-Cyclotron Resonance Ion Source

We have performed a systematic study of the Bremsstrahlung emission from the electrons in the plasma of a commercial 14.5 GHz Electron-Cyclotron Resonance Ion Source. The electronic spectral temperature and the product of ionic and electronic densities of the plasma are measured by analyzing the Bremsstrahlung spectra recorded for several rare gases (Ar, Kr, Xe) as a function of the injected power. Within our uncertainty, we find an average temperature of ? 48 keV above 100W, with a weak dependency on the injected power and gas composition. Charge state distributions of extracted ion beams have been determined as well, providing a way to disentangle the ionic density from the electronic density. Moreover X-ray emission from highly charged argon ions in the plasma has been observed with a high-resolution mosaic crystal spectrometer, demonstrating the feasibility for high-precision measurements of transition energies of highly charged ions, in particular of the magnetic dipole (M1) transition of He-like of argon ions

Quantum phase retrieval of a Rydberg wave packet using a half-cycle pulse

A terahertz half-cycle pulse was used to retrieve information stored as quantum phase in an $N$-state Rydberg atom data register. The register was prepared as a wave packet with one state phase-reversed from the others (the "marked bit"). A half-cycle pulse then drove a significant portion of the electron probability into the flipped state via multimode interference.Comment: accepted by PR

Collisionless dynamics of dilute Bose gases: Role of quantum and thermal fluctuations

We study the low-energy collective oscillations of a dilute Bose gas at finite temperature in the collisionless regime. By using a time-dependent mean-field scheme we derive for the dynamics of the condensate and noncondensate components a set of coupled equations, which we solve perturbatively to second order in the interaction coupling constant. This approach is equivalent to the finite-temperature extension of the Beliaev approximation and includes corrections to the Gross-Pitaevskii theory due both to quantum and thermal fluctuations. For a homogeneous system we explicitly calculate the temperature dependence of the velocity of propagation and damping rate of zero sound. In the case of harmonically trapped systems in the thermodynamic limit, we calculate, as a function of temperature, the frequency shift of the low-energy compressional and surface modes.Comment: 26 pages, RevTex, 8 ps figure

Performance of Monolayer Graphene Nanomechanical Resonators with Electrical Readout

The enormous stiffness and low density of graphene make it an ideal material for nanoelectromechanical (NEMS) applications. We demonstrate fabrication and electrical readout of monolayer graphene resonators, and test their response to changes in mass and temperature. The devices show resonances in the MHz range. The strong dependence of the resonant frequency on applied gate voltage can be fit to a membrane model, which yields the mass density and built-in strain. Upon removal and addition of mass, we observe changes in both the density and the strain, indicating that adsorbates impart tension to the graphene. Upon cooling, the frequency increases; the shift rate can be used to measure the unusual negative thermal expansion coefficient of graphene. The quality factor increases with decreasing temperature, reaching ~10,000 at 5 K. By establishing many of the basic attributes of monolayer graphene resonators, these studies lay the groundwork for applications, including high-sensitivity mass detectors