True airspeed measured by airborne laser Doppler velocimeter

Velocimeter utilizing carbon dioxide laser measures true airspeed of aircraft. Results of flight tests indicate that clear-weather airspeeds can be measured with accuracy better than 0.1% at altitudes up to 3000 meters; measurements can be made at much greater altitudes in cloudy or turbid air

Investigation of the chemical kinetics of an advanced high energy propellant system Quarterly progress report, 1 Jun. - 1 Sep. 1968

Reaction kinetics of high energy oxygen difluoride diborane propellant syste

Mantle formation, coagulation and the origin of cloud/core-shine: II. Comparison with observations

Many dense interstellar clouds are observable in emission in the near-IR, commonly referred to as "Cloudshine", and in the mid-IR, the so-called "Coreshine". These C-shine observations have usually been explained with grain growth but no model has yet been able to self-consistently explain the dust spectral energy distribution from the near-IR to the submm. We want to demonstrate the ability of our new core/mantle evolutionary dust model THEMIS (The Heterogeneous dust Evolution Model at the IaS), which has been shown to be valid in the far-IR and submm, to reproduce the C-shine observations. Our starting point is a physically motivated core/mantle dust model. It consists of 3 dust populations: small aromatic-rich carbon grains; bigger core/mantle grains with mantles of aromatic-rich carbon and cores either made of amorphous aliphatic-rich carbon or amorphous silicate. We assume an evolutionary path where these grains, when entering denser regions, may first form a second aliphatic-rich carbon mantle (coagulation of small grains, accretion of carbon from the gas phase), second coagulate together to form large aggregates, and third accrete gas phase molecules coating them with an ice mantle. To compute the corresponding dust emission and scattering, we use a 3D Monte-Carlo radiative transfer code. We show that our global evolutionary dust modelling approach THEMIS allows us to reproduce C-shine observations towards dense starless clouds. Dust scattering and emission is most sensitive to the cloud central density and to the steepness of the cloud density profile. Varying these two parameters leads to changes, which are stronger in the near-IR, in both the C-shine intensity and profile. With a combination of aliphatic-rich mantle formation and low-level coagulation into aggregates, we can self-consistently explain the observed C-shine and far-IR/submm emission towards dense starless clouds.Comment: Paper accepted for publication in A&A with companion paper "Mantle formation, coagulation and the origin of cloud/core-shine: I. Dust scattering and absorption in the IR", A.P Jones, M. Koehler, N. Ysard, E. Dartois, M. Godard, L. Gavila

Infections Associated with Bartonella Species in Persons Infected with Human Immunodeficiency Virus

Two members of the genus Bartonella, Bartonella quintana (formerly Rochalimaea quintana) and Bartonella henselae (formerly Rochalimaea henselae), have recently been recognized as agents of severe or fatal disease in patients infected with human immunodeficiencyv irus (HIV). The development of infection with B. henselae in HIV-infected individuals has been associated with traumatic contact with cats (scratches or bites), and domestic cats have been identified as a major reservoir for this organism. Specific information regarding the transmission of B. henselae to humans is not yet available, but common-sense precautions that minimize exposure to cat-associated organisms are appropriate. Preliminary accounts suggest that B. quintana infections are more common than B. henselae infections among HIV-infected individuals in San Francisco. The source of infection with B. quintana and the mechanism of its transmission remain unknown

Magnetic behavior of EuCu2As2: Delicate balance between antiferromagnetic and ferromagnetic order

The Eu-based compound, EuCu2As2, crystallizing in the ThCr2Si2-type tetragonal structure, has been synthesized and its magnetic behavior has been investigated by magnetization (M), heat-capacity (C) and electrical resistivity (rho) measurements as a function of temperature (T) and magnetic field (H) as well as by 151Eu Moessbauer measurements. The results reveal that Eu is divalent ordering antiferromagnetically below 15 K in the absence of magnetic field, apparently with the formation of magnetic Brillouin-zone boundary gaps. A fascinating observation is made in a narrow temperature range before antiferromagnetism sets in: That is, there is a remarkable upturn just below 20 K in the plot of magnetic susceptibility versus T even at low fields, as though the compound actually tends to order ferromagnetically. There are corresponding anomalies in the magnetocaloric effect data as well. In addition, a small application of magnetic field (around 1 kOe at 1.8 K) in the antiferromagnetic state causes spin-reorientation effect. These results suggest that there is a close balance between antiferromagnetism and ferromagnetism in this compoundComment: Phys. Rev. B, in pres

Testing T Invariance in the Interaction of Slow Neutrons with Aligned Nuclei

The study of five-fold (P even, T odd) correlation in the interaction of slow polarized neutrons with aligned nuclei is a possible way of testing the time reversal invariance due to the expected enhancement of T violating effects in compound resonances. Possible nuclear targets are discussed which can be aligned both dynamically as well as by the "brute force" method at low temperature. A statistical estimation is performed of the five-fold correlation for low lying p wave compound resonances of the $^{121}$Sb, $^{123}$Sb and $^{127}$I nuclei. It is shown that a significant improvement can be achieved for the bound on the intensity of the fundamental parity conserving time violating (PCTV) interaction.Comment: 22 pages, 5 figures, published versio

The role of body rotation in bacterial flagellar bundling

In bacterial chemotaxis, E. coli cells drift up chemical gradients by a series of runs and tumbles. Runs are periods of directed swimming, and tumbles are abrupt changes in swimming direction. Near the beginning of each run, the rotating helical flagellar filaments which propel the cell form a bundle. Using resistive-force theory, we show that the counter-rotation of the cell body necessary for torque balance is sufficient to wrap the filaments into a bundle, even in the absence of the swirling flows produced by each individual filament

Mantle formation, coagulation and the origin of cloud/core shine: I. Modelling dust scattering and absorption in the infra-red

Context. The observed cloudshine and coreshine (C-shine) have been explained in terms of grain growth leading to enhanced scatter- ing from clouds in the J, H and K photometric bands and the Spitzer IRAC 3.6 and 4.5 {\mu}m bands. Aims. Using our global dust modelling approach THEMIS (The Heterogeneous dust Evolution Model at the IaS) we explore the effects of dust evolution in dense clouds, through aliphatic-rich carbonaceous mantle formation and grain-grain coagulation. Methods. We model the effects of wide band gap a-C:H mantle formation and the low-level aggregation of diffuse interstellar medium dust in the moderately-extinguished outer regions of molecular clouds. Results. The formation of wide band gap a-C:H mantles on amorphous silicate and amorphous carbon (a-C) grains leads to a decrease in their absorption cross-sections but no change in their scattering cross-sections at near-IR wavelengths, resulting in higher albedos. Conclusions. The evolution of dust, with increasing density and extinction in the diffuse to dense molecular cloud transition, through mantle formation and grain aggregation, appears to be a likely explanation for the observed C-shine.Comment: 12 pages, 15 figures, accepted for publication in A&A along with the companion paper entitled, Mantle formation, coagulation and the origin of cloud/core shine: II Comparison with observations, by Ysard et al. (also accepted for publication in A&A