Automated Verification of Specifications with Typestates and Access Permissions

We propose an approach to formally verify Plural specifications based on access permissions and typestates, by model-checking automatically generated abstract state-machines. Our exhaustive approach captures all the possible behaviors of abstract concurrent programs implementing the specification. We describe the formal methodology employed by our technique and provide an example as proof of concept for the state-machine construction rules. The implementation of a fully automated algorithm to generate and verify models, currently underway, provides model checking support for the Plural tool, which currently supports only program verification via data flow analysis (DFA)

A Machine-Checked Proof of A State-Space Construction Algorithm

This paper presents the correctness proof of Saturation, an algorithm for generating state spaces of concurrent systems, implemented in the SMART tool. Unlike the Breadth First Search exploration algorithm, which is easy to understand and formalise, Saturation is a complex algorithm, employing a mutually-recursive pair of procedures that compute a series of non-trivial, nested local fixed points, corresponding to a chaotic fixed point strategy. A pencil-and-paper proof of Saturation exists, but a machine checked proof had never been attempted. The key element of the proof is the characterisation theorem of saturated nodes in decision diagrams, stating that a saturated node represents a set of states encoding a local fixed-point with respect to firing all events affecting only the node s level and levels below. For our purpose, we have employed the Prototype Verification System (PVS) for formalising the Saturation algorithm, its data structures, and for conducting the proofs

Automated Verification of Specifications with Typestates and Access Permissions

We propose an approach to formally verify Plural specifications  of concurrent programs based on access permissions and  typestates, by model-checking automatically generated abstract  state-machines. Our approach captures all possible relevant  behaviors of abstract concurrent programs implementing the  specification. We describe the formal methodology employed in  our technique and provide an example as proof of concept for the  state-machine construction rules.  We implemented the fully automated algorithm to generate and  verify models as a freely available plug-in of the Plural tool,  called Pulse.  We tested Pulse on the full specification of a  Multi Threaded Task Server commercial application and showed  that this approach scales well and is efficient in finding  errors in specifications that could not be previously detected  with the Data Flow Analysis (DFA) capabilities of Plural

The 4-H Club Meeting: An Essential Youth Development Strategy

The club meeting has served as a key delivery method for 4-H programming across the United States throughout its history. A survey of WV 4-H community club members reinforces the body of evidence that the 4-H club meeting is an effective vehicle for delivering positive youth learning opportunities within the umbrella of the Essential Elements of 4-H youth development programming. This article discusses the findings of the West Virginia study and addresses the delivery of effective 4-H club programming that incorporates the Essential Elements

Variation of the ultraviolet extinction law across the Taurus-Auriga star forming complex. A GALEX based study

The Taurus-Auriga molecular complex (TMC) is the main laboratory for the study of low mass star formation. The density and properties of interstellar dust are expected to vary across the TMC. These variations trace important processes such as dust nucleation or the magnetic field coupling with the cloud. In this article, we show how the combination of near ultraviolet (NUV) and infrared (IR) photometry can be used to derive the strength of the 2175 \AA\ bump and thus any enhancement in the abundance of small dust grains and PAHs in the dust grains size distribution. This technique is applied to the envelope of the TMC, mapped by the GALEX All Sky Survey (AIS). UV and IR photometric data have been retrieved from the GALEX-AIS and the 2MASS catalogues. NUV and K-band star counts have been used to identify the areas in the cloud envelope where the 2175 \AA\ bump is weaker than in the diffuse ISM namely, the low column density extensions of L1495, L1498 and L1524 in Taurus, L1545, L1548, L1519, L1513 in Auriga and L1482-83 in the California region. This finding agrees with previous results on dust evolution derived from Spitzer data and suggests that dust grains begin to decouple from the environmental galactic magnetic field already in the envelope.Comment: Accepted in Monthly Notices of the Royal Astronomical Societ

Energy Production, Decontamination, and Hydrogenation Reactions over Perovskite-Type Oxide Catalyst

Heterogeneous catalysis is an important tool in industrial processes because of the recoverability of the catalysts. Transition metal perovskites-type oxides, with the general formula ABO3, offer attractive alternative to noble metal catalysts due to their high activity, high thermal stability, and low cost. Moreover, their physicochemical properties can be tailored to create a family of catalysts by varying the compositions of A and B. Indeed, the partial substitution at the A- and/or B-site with another metal cation stabilizes unusual oxidation states of the B cation with the simultaneous formation of structural defects. In particular, lanthanum-based perovskites have been used extensively and can be grouped into: (i) perovskites with oxygen vacancies as catalysts for oxidation reactions and (ii) perovskites as precursors to prepare nanosized catalysts for hydrogenation reactions. This chapter focuses on the use of pure and doped lanthanum perovskites as active and selective heterogeneous catalysts for catalytic energy production reaction (DME combustion), decontamination reactions (methane, acetyl acetate, toluene, n-hexane, and soot combustion), and hydrogenation reactions (guaiacol, glycerol, and xylose hydrogenation)

Instrumental methods for neutron spectroscopy in the MIT blanket test facility

"May, 1972."Also issued as an Sc. D. thesis by the first author and supervised by the third and fourth author, MIT Dept. of Nuclear Engineering, 1972Includes bibliographical references (pages 223-225)U.S. Atomic Energy Commission contractThe energy spectrum of the neutron flux in a realistic mockup of the blanket region of a large liquid-metal-cooled fast breeder reactor was measured using three different spectrometers: He-3 and Li-6 semiconductor detectors and a Proton-Recoil proportional counter. The He-3 detector was operated in the sum and difference modes, and the Li-6 detector in the sum, difference and triton modes. The experimental data was unfolded using direct, integral and derivative techniques. Methods were developed or perfected to enable use of the He-3 detector over the neutron energy range from 10 keV to 1.3 MeV and the Li-6 detector from 10 keV to 3.1 MeV; the Proton-Recoil detector was operated in the region from 2 keV to 1.5 MeV. In general, good agreement was found between the experimental measurements for all detector types, modes of operation and methods of unfolding, except for the low-energy He-3 data. The present experimental results and previously reported data obtained using a method based on gamma line broadening are in relatively good agreement in the high energy region above 0.8 MeV. The measured neutron spectrum is also similar in shape to neutron spectra measured at ANL in critical assembly mockups of large LMFBR cores, but systematically softer, as expected.. However, there is a large discrepancy in the energy region from 10 keV to 50 keV between the present results and either spectra unfolded from foil data or those numerically calculated using the 1-D ANISN code in the S8 option with 26 energy groups

The whole-brain pattern of magnetic susceptibility perturbations in Parkinson's disease

Although iron-mediated oxidative stress has been proposed as a potential pathomechanism in Parkinson's disease, the global distribution of iron accumulation in Parkinson's disease has not yet been elucidated. This study used a new magnetic resonance imaging contrast, quantitative susceptibility mapping, and state-of-the-art methods to map for the first time the whole-brain landscape of magnetostatic alterations as a surrogate for iron level changes in n = 25 patients with idiopathic Parkinson's disease versus n = 50 matched controls. In addition to whole-brain analysis, a regional study including sub-segmentation of the substantia nigra into dorsal and ventral regions and qualitative assessment of susceptibility maps in single subjects were also performed. The most remarkable basal ganglia effect was an apparent magnetic susceptibility increase-consistent with iron deposition-in the dorsal substantia nigra, though an effect was also observed in ventral regions. Increased bulk susceptibility, additionally, was detected in rostral pontine areas and in a cortical pattern tightly concordant with known Parkinson's disease distributions of α-synuclein pathology. In contrast, the normally iron-rich cerebellar dentate nucleus returned a susceptibility reduction suggesting decreased iron content. These results are in agreement with previous post-mortem studies in which iron content was evaluated in specific regions of interest; however, extensive neocortical and cerebellar changes constitute a far more complex pattern of iron dysregulation than was anticipated. Such findings also stand in stark contrast to the lack of statistically significant group change using conventional magnetic resonance imaging methods namely voxel-based morphometry, cortical thickness analysis, subcortical volumetry and tract-based diffusion tensor analysis; confirming the potential of whole-brain quantitative susceptibility mapping as an in vivo biomarker in Parkinson's disease

Mixed RF-VLC Relaying Systems for Interference-Sensitive Mobile Applications

Due to their Radio-Frequency (RF) immunity, Visible Light Communications (VLC) pose as a promising technology for interference sensitive applications such as medical data networks. In this paper, we investigate mixed RF-VLC relaying systems especially suited for this type of applications that support mobility. In this system setup, the end-user, who is assumed to be on a vehicle that is in dynamic movement, is served by an indoor VLC system, while the outdoor data traffic is conveyed through multiple backhaul RF links. Furthermore, it is assumed that a single backhaul RF link is activated by the mobile relay and due to feedback delay, the RF link activation is based on outdated channel state information (CSI). The performance of this system is analyzed in terms of outage probability and bit error rate (BER), and novel closed form analytical expressions are provided. Furthermore, the analysis is extended for the case where the average SNR over the RF links and/or LED optical power is high, and approximate analytical expressions are derived which determine performance floors. Numerical results are provided which demonstrate that the utilization of multiple RF backhaul links can significantly improve overall RF-VLC system performance when outage/BER floors are avoided. This calls upon joint design of both subsystems. Additionally, the outdated CSI exploited for active RF selection can significantly degrade the quality of system performance.Comment: Published in IEEE Transactions on Vehicular Technolog