1,139 research outputs found
On The General Applicability of Instruction-Set Randomization
We describe Instruction-Set Randomization (ISR), a general approach for safeguarding systems against any type of code-injection attack. We apply Kerckhoffs' principle to create OS process-specific randomized instruction sets (e.g., machine instructions) of the system executing potentially vulnerable software. An attacker who does not know the key to the randomization algorithm will inject code that is invalid for that (randomized) environment, causing a runtime exception. Our approach is applicable to machine-language programs and scripting and interpreted languages. We discuss three approaches (protection for Intel x86 executables, Perl scripts, and SQL queries), one from each of the above categories. Our goal is to demonstrate the generality and applicability of ISR as a protection mechanism. Our emulator-based prototype demonstrates the feasibility ISR for x86 executables and should be directly usable on a suitably modified processor. We demonstrate how to mitigate the significant performance impact of emulation-based ISR by using several heuristics to limit the scope of randomized (and interpreted) execution to sections of code that may be more susceptible to exploitation. The SQL prototype consists of an SQL query-randomizing proxy that protects against SQL injection attacks with no changes to database servers, minor changes to CGI scripts, and with negligible performance overhead. Similarly, the performance penalty of a randomized Perl interpreter is minimal. Where the performance impact of our proposed approach is acceptable (i.e., in an already-emulated environment, in the presence of programmable or specialized hardware, or in interpreted languages), it can serve as a broad protection mechanism and complement other security mechanisms
Timed Implementation Relations for the Distributed Test Architecture
In order to test systems that have physically distributed interfaces, called ports, we might use a distributed approach in which there is a separate tester at each port. If the testers do not synchronise during testing then we cannot always determine the relative order of events observed at different ports and this leads to new notions of correctness that have been described using corresponding implementation relations. We study the situation in which each tester has a local clock and timestamps its observations. If we know nothing about how the local clocks relate then this does not affect the implementation relation while if the local clocks agree exactly then we can reconstruct the sequence of observations made. In practice, however, we are likely to be between these extremes: the local clocks will not agree exactly but we have some information regarding how they can differ. We start by assuming that a local tester interacts synchronously with the corresponding port of the system under test and then extend this to the case where communications can be asynchronous, considering both the first-in-first-out (FIFO) case and the non-FIFO case. The new implementation relations are stronger than implementation relations for distributed testing that do not use timestamps but still reflect the distributed nature of observations. This paper explores these alternatives and derives corresponding implementation relations
Theoretical and Phenomenological Constraints on Form Factors for Radiative and Semi-Leptonic B-Meson Decays
We study transition form factors for radiative and rare semi-leptonic B-meson
decays into light pseudoscalar or vector mesons, combining theoretical
constraints and phenomenological information from Lattice QCD, light-cone sum
rules, and dispersive bounds. We pay particular attention to form factor
parameterisations which are based on the so-called series expansion, and study
the related systematic uncertainties on a quantitative level. In this context,
we also provide the NLO corrections to the correlation function between two
flavour-changing tensor currents, which enters the unitarity constraints for
the coefficients in the series expansion.Comment: 52 pages; v2: normalization error in (29ff.) corrected, conclusion
about relevance of unitarity bounds modified; form factor fits unaffected;
references added; v3: discussion on truncation of series expansion added,
matches version to be published in JHEP; v4: corrected typos in Tables 5 and
Clinical course, costs and predictive factors for response to treatment in carpal tunnel syndrome: The PALMS study protocol
Background Carpal tunnel syndrome (CTS) is the most common neuropathy of the upper limb and a significant contributor to hand functional impairment and disability. Effective treatment options include conservative and surgical interventions, however it is not possible at present to predict the outcome of treatment. The primary aim of this study is to identify which baseline clinical factors predict a good outcome from conservative treatment (by injection) or surgery in patients diagnosed with carpal tunnel syndrome. Secondary aims are to describe the clinical course and progression of CTS, and to describe and predict the UK cost of CTS to the individual, National Health Service (NHS) and society over a two year period. Methods/Design In this prospective observational cohort study patients presenting with clinical signs and symptoms typical of CTS and in whom the diagnosis is confirmed by nerve conduction studies are invited to participate. Data on putative predictive factors are collected at baseline and follow-up through patient questionnaires and include standardised measures of symptom severity, hand function, psychological and physical health, comorbidity and quality of life. Resource use and cost over the 2 year period such as prescribed medications, NHS and private healthcare contacts are also collected through patient self-report at 6, 12, 18 and 24 months. The primary outcome used to classify treatment success or failures will be a 5-point global assessment of change. Secondary outcomes include changes in clinical symptoms, functioning, psychological health, quality of life and resource use. A multivariable model of factors which predict outcome and cost will be developed. Discussion This prospective cohort study will provide important data on the clinical course and UK costs of CTS over a two-year period and begin to identify predictive factors for treatment success from conservative and surgical interventions
Law, justice and the role of courts in changing the social superstructure narrative in climate litigation
The teaching of recent and violent conflicts as challenges for history education
This paper has been written with the support of Projects EDU2015-65088P from the DGICYT (Ministry of Education, Spain) and also the Project PICT2012-1594 from the ANPCYT (Argentina) coordinated by the autho
Active, but not passive cigarette smoking was inversely associated with mammographic density
The opposing carcinogenic and antiestrogenic properties of tobacco smoke may explain why epidemiologic studies have not consistently reported positive associations for active smoking and breast cancer risk. A negative relation between mammographic density, a strong breast cancer risk factor, and active smoking would lend support for an antiestrogenic mechanism.
We used multivariable linear regression to assess the associations of active smoking and secondhand smoke (SHS) exposure with mammographic density in 799 pre- and early perimenopausal women in the Study of Women’s Health Across the Nation (SWAN).
We observed that current active smoking was associated with 7.2% lower mammographic density, compared to never active smoking and no SHS exposure (p = 0.02). Starting to smoke before 18 years of age and having smoked ≥20 cigarettes/day were also associated with statistically significantly lower percent densities. Among nulliparous women having smoked ≥20 cigarettes/day was associated with 23.8% lower density, compared to having smoked ≤9 cigarettes/day (p < 0.001).
Our findings support the hypothesis that tobacco smoke exerts an antiestrogenic effect on breast tissue, but counters the known increased risk of breast cancer with smoking prior to first full-term birth. Thus, our data suggest that the antiestrogenic but not the carcinogenic effects of smoking may be reflected by breast density
The impact of cycle proficiency training on cycle-related behaviours and accidents in adolescence: findings from ALSPAC, a UK longitudinal cohort
Different measures of smoking exposure and mammographic density in postmenopausal Norwegian women: a cross-sectional study
Background: Recent cohort studies have suggested an
increased risk of breast cancer with long duration of smoking,
and with smoking initiation before first birth. Cigarette smoking
may have both carcinogenic effects and antiestrogenic effects
on the breast tissue. We decided to examine the relationship
between different measures of smoking exposure and
mammographic density.
Methods: Lifetime smoking history was collected through
interview and questionnaires among 907 postmenopausal
participants in the Tromsø Mammography and Breast Cancer
study. The mammograms were obtained from the governmental
Norwegian Breast Cancer Screening Program. Mammograms
were classified according to the percentage and absolute
mammographic densities using a previously validated computerassisted
method.
Results:Sixty-five percent of the women reported having ever
smoked cigarettes, while 34% were current smokers. After
adjustment for age, age at first birth, parity, age at menopause,
postmenopausal hormone therapy use, and body mass index,
smoking was inversely associated with both measures of
mammographic density (both trends P < 0.01). Both current
smokers and former smokers had significantly lower adjusted
mean percentage mammographic density compared with never
smokers (P = 0.003 and P = 0.006, respectively). An inverse
dose–response relationship with mammographic density was
found between both the number of cigarettes and the number of
pack-years smoked among current smokers. Current smokers
who smoked 11 cigarettes or more daily had a 3.7% absolute
(36% relative difference) lower percentage mammographic
density compared with current smokers who smoked seven
cigarettes or less daily (P = 0.008). When former smokers were
stratified according to time since smoking cessation, we found
that women who had stopped smoking less than 24 years ago
had a significantly lower mean percentage mammographic
density compared with never smokers (P < 0.001).
Conclusion: We found modest inverse dose–response
associations between numbers of cigarettes and of pack-years
smoked and both measures of mammographic density among
current smokers. Former smokers who had stopped smoking
less than 24 years ago also had a statistically significantly lower
mean percentage mammographic density when compared with
never smokers. These findings are consistent with an
antiestrogenic effect of cigarette smoking on the breast tissue
Adults with autism spectrum disorders exhibit decreased sensitivity to reward parameters when making effort-based decisions
- …