A mini challenge: build a verifiable filesystem

We propose tackling a “mini challenge” problem: a nontrivial verification effort that can be completed in 2–3 years, and will help establish notational standards, common formats, and libraries of benchmarks that will be essential in order for the verification community to collaborate on meeting Hoare’s 15-year verification grand challenge. We believe that a suitable candidate for such a mini challenge is the development of a filesystem that is verifiably reliable and secure. The paper argues why we believe a filesystem is the right candidate for a mini challenge and describes a project in which we are building a small embedded filesystem for use with flash memory. The work described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.     

Identification of the thermal phases in firing of kaolinite to mullite by using micro-Raman spectroscopy and curve-fitting

Firing of kaolinite to mullite is an important process in ceramic industry. In the present study, Raman spectroscopy and curve-fitting are utilized for identification of the thermal phases in progressive firing of kaolinite to mullite up to 1300 °C. The results are compared to that observed by XRD. Many natural kaolinites consist of accessory anatase, and this mineral has strong Raman bands. Therefore, the spectra of anatase-free and anatase-containing kaolinites were analyzed. The Raman response is sensitive to the degree of the structural order of the thermal phases. Dehydroxylated kaolinite is detected at 500 °C by the disappearance of the Raman bands of the kaolinite. The metakaolinite at 700 °C and the spinel-type phase at 1000 °C have broad and weak Raman bands due to their short-range and poorly-order structure, respectively. Amorphous silica is observed at 1000 °C by the development of diagnostic broad and weak Raman bands. Mullite and cristobalite are detected at 1300 °C by the appearance of characteristic Raman bands. In firing of anatase-containing kaolinite, progressive thermal transform from anatase to rutile is observed at 1100–1300 °C by the appearance of Raman bands of rutile and by the decreasing of the anatase bands. The results can be applied in using micro-Raman spectroscopy as a non-destructive method for identification of thermal phases in the composition of modern and ancient ceramic.     

Contingency management and levodopa-carbidopa for cocaine treatment: A comparison of three behavioral targets.

New data support use of levodopa pharmacotherapy with behavioral contingency management (CM) as one efficacious combination in cocaine dependence disorder treatment. A potential mechanism of the combined treatment effects may be related to dopamine-induced enhancement of the saliency of contingently delivered reinforcers. Evidence to support this mechanism was sought by evaluating levodopa-enhancing effects across distinct CM conditions that varied in behavioral targets. A total of 136 treatment-seeking, cocaine dependent subjects participated in this 12-week, randomized, placebo-controlled trial of levodopa (vs. placebo) administered in combination with one of three behavioral CM conditions. In the CM-URINE condition, subjects received cash-valued vouchers contingent on cocaine-negative urine toxicology results. In the CM-ATTEND condition, the same voucher schedule was contingent on attending thrice weekly clinic visits. In the CM-MEDICATION condition, the same voucher schedule was contingent on Medication Event Monitoring Systems- and riboflavin-based evidence of pill-taking behavior. Primary outcomes associated with each CM target behavior were analyzed using generalized linear mixed models for repeated outcomes. CM responding in the CM-ATTEND and CM-MEDICATION conditions showed orderly effects, with each condition producing corresponding changes in targeted behaviors, regardless of medication condition. In contrast, CM responding in the CM-URINE condition was moderated by medication, with levodopa-treated subjects more likely to submit cocaine-negative urines. These findings specify the optimal target behavior for CM when used in combination with levodopa pharmacotherapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strong Purcell effect for InAs quantum boxes in three-dimensionalsolid-state microcavities

A strong enhancement of the spontaneous emission rate (Purcell effect) has been observed for self-assembled InAs/GaAs quantum boxes inserted in GaAs-based pillar microcavities (×5) and microdisks (×15) using time-resolved as well as c.w. photoluminescence experiments. We show that the magnitude of the Purcell effect can be quantitatively understood by considering both the Purcell figure of merit F_p of such cavities (F_p≫1) and the spatial/spectral distribution of the inhomogeneous collection of atom-like emitters. These results open the way to the development of single-photon devices such as photon-guns or photon-turnstiles, able to emit photons one-by-one in a deterministic way     

Thomas C. O’Connor (1931–2012)

Copyright 2013 American Association for Aerosol Research     

A mathematical model,implementation and study of a swarm system

The work reported in this paper is motivated towards the development of a mathematical model for swarm systems based on macroscopic primitives. A pattern formation and transformation model is proposed. The pattern transformation model comprises two general methods for pattern transformation, namely a macroscopic transformation method and a mathematical transformation method. The problem of transformation is formally expressed and four special cases of transformation are considered. Simulations to confirm the feasibility of the proposed models and transformation methods are presented. Comparison between the two transformation methods is also reported.     

A two-platform task reveals a deficit in the ability of rats to return to the start location in the water maze.

The ability of rats to return to the start location was examined with a 4-arm radial water maze. The task required rats to find 2 hidden platforms in sequence. Rats were released from 1 of 3 arms and there was a platform located in the fourth arm. Once a rat found this platform, a 2nd platform was raised in another location, which was either the start location, for 1 group, or another fixed location, for a control group. Across 3 experiments, all rats learned the location of the 1st fixed platform in 80 to 120 trials. However, rats had difficulty finding a 2nd platform if it was at the start location. Control groups revealed that rats could learn 2 platform locations and that the difficulty in learning to return to the start location did not seem to be attributable to its aversive nature. In separate groups, exposure to the start location was increased by starting the rats from an initially stable platform. Rats still did not readily learn to return to the start location. The authors suggest that start location, when varied, cannot readily be used to define the location of a hidden platform. (PsycINFO Database Record (c) 2010 APA, all rights reserved)