41,780 research outputs found

    Machine Assisted Proof of ARMv7 Instruction Level Isolation Properties

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    In this paper, we formally verify security properties of the ARMv7 Instruction Set Architecture (ISA) for user mode executions. To obtain guarantees that arbitrary (and unknown) user processes are able to run isolated from privileged software and other user processes, instruction level noninterference and integrity properties are provided, along with proofs that transitions to privileged modes can only occur in a controlled manner. This work establishes a main requirement for operating system and hypervisor verification, as demonstrated for the PROSPER separation kernel. The proof is performed in the HOL4 theorem prover, taking the Cambridge model of ARM as basis. To this end, a proof tool has been developed, which assists the verification of relational state predicates semi-automatically

    Evolution in the split-peak structure across the Peak Effect region in single crystals of 2H2H-NbSe2_2

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    We have explored the presence of a two-peak feature spanning the peak effect (PE) region in the ac susceptibility data and the magnetization hysteresis measurements over a wide field-temperature regime in few weakly pinned single crystals of 2H2H-NbSe2_2, which display reentrant characteristic in the PE curve near TcT_c(0). We believe that the two-peak feature evolves into distinct second magnetization peak anomaly well separated from the PE with gradual enhancement in the quenched random pinning.Comment: 9 figure

    Indonesia against the trend? Ageing and inter-generational wealth flows in two Indonesian communities

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    Indonesian family systems do not conform to the prevailing image of Asian families, the predominant arrangements being nuclear and bilateral, with an important matrilineal minority. This paper considers the strength of family ties in two communities, focussing particularly on inter-generational flows of support to and from older members. Data are drawn from a longitudinal anthropological demography that combines ethnographic and panel survey methods. Several sources of variation in family ties are detailed, particularly the heterogeneity of support flows - balanced, upward, and downward - that co-exist in both communities. Different norms in each locale give sharply contrasting valuations of these flows. The ability of families to observe norms is influenced by the effectiveness of networks and by socio-economic status

    PICES Press, Vol. 16, No. 2, July 2008

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    The 2008 Inter-Sessional Science Board Meeting (pp.1-2, pdf, 0.1 Mb) FUTURE – From Science Plan to Implementation Plan (pp. 3-4, pdf, 0.1 Mb) CFAME Task Team Workshop – Linking and Visualising (p. 5, pdf, 0.1 Mb) PICES WG 21 Meets in Busan, Korea: The Database Meeting (pp. 6-7, pdf, 0.1 Mb) ICES-PICES-IOC Symposium on Climate Change (pp. 8-12, pdf, 1.2 Mb) Zooplankton and Climate: Response Modes and Linkages (pp. 13-15, pdf, 0.2 Mb) PICES Fishery Science Committee Workshop in Gijón (pp. 16-18, pdf, 0.1 Mb) The North Pacific Continuous Plankton Recorder Survey (pp. 19-21, pdf, 0.4 Mb) PICES Ecosystem Status Report Wins Design Award (p. 21, pdf, 0.4 Mb) Canada’s Three Oceans (C3O): A Canadian Contribution to the International Polar Year (pp. 22-25, pdf, 0.8 Mb) New Surface Mooring at Station Papa Monitors Climate (pp. 26-27, pdf, 0.2 Mb) The State of the Western North Pacific in the Second Half of 2007 (pp. 28-29, pdf, 0.4 Mb) The Bering Sea: Current Status and Recent Events (pp. 30-31, pdf, 0.4 Mb) Recent Trends in Waters of the Subarctic NE Pacific (pp.32-33, pdf, 0.3 Mb) 2009 Vintage of Fraser River Sockeye Salmon: A Complex Full Bodied Redd with Mysterious Bouquet (p. 34, pdf, 0.1 Mb) Pacific Biological Station Celebrates Centennial Anniversary, 1908–2008 (p. 35, pdf, 0.3 Mb) Marine and Coastal Fisheries: American Fisheries Society Open Access E-journal (p. 36, pdf, 0.1 Mb) Latest and Upcoming PICES Publications (p. 36, pdf, 0.1 Mb

    The roles of inter- and intra-sexual selection in behavioral isolation between native and invasive pupfishes

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    Male-male competition and female mate choice may both play important roles in driving and maintaining reproductive isolation between species. When previously allopatric species come into secondary contact with each other due to introductions, they provide an opportunity to evaluate the identity and strength of reproductive isolating mechanisms. If reproductive isolation is not maintained, hybridization may occur. We examined how reproductive isolating mechanisms mediate hybridization between endemic populations of the Red River pupfish Cyprinodon rubrofluviatilis and the recently introduced sheepshead minnow C. variegatus. In lab-based dominance trials, males of both species won the same number of competitions. However, male C. rubrofluviatilis that won competitions were more aggressive than C. variegatus winners, and more aggression was needed to win against competitor C. variagatus than allopatric C. rubrofluviatilis. Duration of fights also differed based on the relatedness of the competitor. In dichotomous mate choice trials, there were no conspecific or heterospecific preferences expressed by females of either species. Our findings that male-male aggression differs between closely and distantly related groups, but female choice does not suggest that male-male competition may be the more likely mechanism to impede gene flow in this system

    Hypervisor Integrity Measurement Assistant

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    An attacker who has gained access to a computer may want to upload or modify configuration files, etc., and run arbitrary programs of his choice. We can severely restrict the power of the attacker by having a white-list of approved file checksums and preventing the kernel from loading loading any file with a bad checksum. The check may be placed in the kernel, but that requires a kernel that is prepared for it. The check may also be placed in a hypervisor which intercepts and prevents the kernel from loading a bad file. We describe the implementation of and give performance results for two systems. In one the checksumming, or integrity measurement, and decision is performed by the hypervisor instead of the OS. In the other only the final integrity decision is done in the hypervisor. By moving the integrity check out from the VM kernel it becomes harder for the intruder to bypass the check. We conclude that it is technically possible to put file integrity control into the hypervisor, both for kernels without and with pre-compiled support for integrity measurement
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