Usefulness of multifrequency MST radar measurements, part 2.6B

Scattering of radio waves from atmospheric refractive-index irregularities induced by turbulence was invoked almost four decades ago to explain the characteristics of signals received on VHF/UHF ionospheric and tropospheric forward-scatter links. Due to the bistatic geometry of these links a slender, horizontally extended, common volume or cell is formed in space. The principal contribution to scattering arises from refractive-index fluctuations in this volume at the Bragg wave number K approx. sub B = K approx. sub i -k approx. sub s vectors. It has been surmised that the use of more than one frequency in probing the middle-atmosphere regions should help resolve several issues pertaining to the scattering mechanism. These issues are briefly re-examined in this note. The implications of the radar equation are discussed. The problems arising due to layered structure of turbulence and the choice of frequencies most suitable for multifrequency measurements are considered

Simultaneous VHF and UHF radar observation of the mesosphere at Arecibo during a solar flare: A check on the gradient-mixing hypothesis

The results of a two wavelength (VHF and UHF) mesosphere experiment performed at the Arecibo Observatory on January 5, 1981 are discussed. The 46.8-MHz VHF radar (3.21 m Bragg scale) was operated to provide spectral measurements of signals scattered from refractivity fluctuations due to turbulence. Other physical parameters such as radial velocities, scattered signal power, and Doppler spread due to turbulence can be derived from signal spectra. The 430-MHz UHF radar (0.36 m Bragg scale) was used for D-region electron-density measurements using the incoherent scatter technique with a comparable height resolution. The radars were pointed symmetrically about the vertical with a beam spacing of 5.5 degree in the meridional plane. Occurrence of a type 4 solar flare during the experiment produced enhanced D-region electron-density gradients. This was a unique circumstance that provided the possibility of testing the basic premises of the turbulent gradient-mixing hypothesis

Interference detection and correction applied to incoherent-scatter radar power spectrum measurement

A median filter based interference detection and correction technique is evaluated and the method applied to the Arecibo incoherent scatter radar D-region ionospheric power spectrum is discussed. The method can be extended to other kinds of data when the statistics involved in the process are still valid

Belousov-Zhabotinskii Reaction with Acetone- Tartaric Acid & Acetone-Mandelic Acid as Organic Substrates

338-33

CONFLLVM: A Compiler for Enforcing Data Confidentiality in Low-Level Code

We present an instrumenting compiler for enforcing data confidentiality in low-level applications (e.g. those written in C) in the presence of an active adversary. In our approach, the programmer marks secret data by writing lightweight annotations on top-level definitions in the source code. The compiler then uses a static flow analysis coupled with efficient runtime instrumentation, a custom memory layout, and custom control-flow integrity checks to prevent data leaks even in the presence of low-level attacks. We have implemented our scheme as part of the LLVM compiler. We evaluate it on the SPEC micro-benchmarks for performance, and on larger, real-world applications (including OpenLDAP, which is around 300KLoC) for programmer overhead required to restructure the application when protecting the sensitive data such as passwords. We find that performance overheads introduced by our instrumentation are moderate (average 12% on SPEC), and the programmer effort to port OpenLDAP is only about 160 LoC.Comment: Technical report for CONFLLVM: A Compiler for Enforcing Data Confidentiality in Low-Level Code, appearing at EuroSys 201

Complexes of Cu(II), Pd(II) & Pt(II) with Schiff Bases Derived from 2-(2'-Aminoethyl)pyridine

47-4

Correlation of IR Data with the Stability of Pt(IV), Ir(III), Rh(III), Ru(III), Co(III), Cr(III), Ni(II), Pt(IV), Pd(II) & Cu(II) Complexes of 3.3'-Diamino-4,4'-dihydroxydiphenyl Sulphone

813-81

Terdentate Ligands: Part II - Octahedral Ni(II), Co(II) & Cr(III) Complexes of Schiff Bases Derived from 2-(2'-Amino-ethyl)pyridine

748-75