637 research outputs found
Generating Property-Directed Potential Invariants By Backward Analysis
This paper addresses the issue of lemma generation in a k-induction-based
formal analysis of transition systems, in the linear real/integer arithmetic
fragment. A backward analysis, powered by quantifier elimination, is used to
output preimages of the negation of the proof objective, viewed as unauthorized
states, or gray states. Two heuristics are proposed to take advantage of this
source of information. First, a thorough exploration of the possible
partitionings of the gray state space discovers new relations between state
variables, representing potential invariants. Second, an inexact exploration
regroups and over-approximates disjoint areas of the gray state space, also to
discover new relations between state variables. k-induction is used to isolate
the invariants and check if they strengthen the proof objective. These
heuristics can be used on the first preimage of the backward exploration, and
each time a new one is output, refining the information on the gray states. In
our context of critical avionics embedded systems, we show that our approach is
able to outperform other academic or commercial tools on examples of interest
in our application field. The method is introduced and motivated through two
main examples, one of which was provided by Rockwell Collins, in a
collaborative formal verification framework.Comment: In Proceedings FTSCS 2012, arXiv:1212.657
Aeneas of Gaza on the Soul
Aeneas of Gaza’s late fifth-century dialogue the Theophrastus investigates philosophical theories about the pre-existence and immortality of the soul in the course of making a Christian case against the Neoplatonic doctrine of the eternity of the world. I explore Aeneas’ knowledge of theories about the soul in the Greek philosophical tradition and his rebuttals of them. Aeneas’ arguments are indebted to earlier philosophers and touch on Origenist ideas most likely arising in local monasteries. His arguments about the pre-existence of the soul thus illumine creative interactions between Christians and philosophers, monks and school-men in late antique Gaza
Genetic algorithm and tabu search approaches to quantization for DCT-based image compression
Today there are several formal and experimental methods for image compression, some of which have grown to be incorporated into the Joint Photographers Experts Group (JPEG) standard. Of course, many compression algorithms are still used only for experimentation mainly due to various performance issues. Lack of speed while compressing or expanding an image, poor compression rate, and poor image quality after expansion are a few of the most popular reasons for skepticism about a particular compression algorithm. This paper discusses current methods used for image compression. It also gives a detailed explanation of the discrete cosine transform (DCT), used by JPEG, and the efforts that have recently been made to optimize related algorithms. Some interesting articles regarding possible compression enhancements will be noted, and in association with these methods a new implementation of a JPEG-like image coding algorithm will be outlined. This new technique involves adapting between one and sixteen quantization tables for a specific image using either a genetic algorithm (GA) or tabu search (TS) approach. First, a few schemes including pixel neighborhood and Kohonen self-organizing map (SOM) algorithms will be examined to find their effectiveness at classifying blocks of edge-detected image data. Next, the GA and TS algorithms will be tested to determine their effectiveness at finding the optimum quantization table(s) for a whole image. A comparison of the techniques utilized will be thoroughly explored
Relationship Between Oral Health and Clinical Osteoporosis Among Hospitalized Patients with and Without Diabetes
Objective: Diabetes mellitus (DM) is associated with poor oral health and osteoporosis (OP). The aim of this study was to assess the relationship between OP, periodontal disease (PD), and other dental and health outcomes in a cohort of hospitalized patients with and without DM. Method: Using a cross-sectional study design, we enrolled consecutive hospitalized patients. We administered a questionnaire to gather demographic information, oral health history, smoking history, and history of OP. We inspected their dentition and reviewed their charts. Data were analyzed using t-tests, chi-square tests, and logistic regression models. Result: Out of 301 patients enrolled, 275 had PD, 102 had DM, and 30 had OP. In univariate analyses, factors associated with OP included older age... (See full abstract in article)
But were they talking about emotions? Affectus, affectio, and the history of emotions
This study investigates how Latinate writers from the classical world to the early modern might have referenced the concept of 'emotion'. It focuses on the polyvalent terms 'affectus' and 'affectio', as these not only appear to have been heavily implicated in premodern discourses about emotional states and dispositions, but are also the cognates of modern terms, such as 'affect' and 'affection', that are undeniably emotions-centred. The study provides a preliminary survey of what the terms 'affectus' and 'affectio' could denote in terms of emotions, considers whether they were synonyms or signified discretely, and explores the expansion of their meaning when used in compounds with terms denoting the mind or body. It uncovers no teleology, but rather the likelihood that usage was modulated according to genre and authority. In conclusion it suggests points of departure for further research that will be able to nuance and complicate this important word history
Beyond the bottom line:redefining the value of design in SME formation
For SMEs to operate in the complex and globalised economic landscape of today engaging with innovation can sustain competitive advantage. Within Design Management, design is being increasingly posited as a strategic resource to facilitate the absorption of new design resources and leverage design knowledge in ways that support SMEs through such economic pressures. Evidencing the relationship between design and economic performance is complex, leading to extensive current research and industry efforts to show how design adds economic value. Despite the value of such efforts, it is important to recognise that innovation means different things to different organizations, especially for start-ups and SMEs. Within the rising tide of design-led innovation, there is a gap being explored in how design can effectively capture and evaluate its contribution within the complex and diverse situations of business development it engages. In seeking to address this gap, this paper presents findings from research undertaken within Design in Action (DiA), an AHRC-funded knowledge exchange hub. Presenting DiA as a single case study, the paper offers methodical reflection on five case example start-up businesses funded by DiA in order to explore the value that design-led innovation approaches offered in their formation
Constraining the dense matter equation-of-state with radio pulsars
Radio pulsars provide some of the most important constraints for our
understanding of matter at supranuclear densities. So far, these constraints
are mostly given by precision mass measurements of neutron stars (NS). By
combining single measurements of the two most massive pulsars, J03480432 and
J07406620, the resulting lower limit of 1.98 (99% confidence) of
the maximum NS mass, excludes a large number of equations of state (EOSs).
Further EOS constraints, complementary to other methods, are likely to come
from the measurement of the moment of inertia (MOI) of binary pulsars in
relativistic orbits. The Double Pulsar, PSR J07373039A/B, is the most
promising system for the first measurement of the MOI via pulsar timing.
Reviewing this method, based in particular on the first MeerKAT observations of
the Double Pulsar, we provide well-founded projections into the future by
simulating timing observations with MeerKAT and the SKA. For the first time, we
account for the spin-down mass loss in the analysis. Our results suggest that
an MOI measurement with 11% accuracy (68% confidence) is possible by 2030. If
by 2030 the EOS is sufficiently well known, however, we find that the Double
Pulsar will allow for a 7% test of Lense-Thirring precession, or alternatively
provide a -measurement of the next-to-leading order gravitational
wave damping in GR. Finally, we demonstrate that potential new discoveries of
double NS systems with orbital periods shorter than that of the Double Pulsar
promise significant improvements in these measurements and the constraints on
NS matter.Comment: 13 pages, 8 figures. Accepted by MNRA
Identification of subgroups with differential treatment effects for longitudinal and multiresponse variables
We describe and evaluate a regression tree algorithm for finding subgroups with differential treatments effects in randomized trials with multivariate outcomes. The data may contain missing values in the outcomes and covariates, and the treatment variable is not limited to two levels. Simulation results show that the regression tree models have unbiased variable selection and the estimates of subgroup treatment effects are approximately unbiased. A bootstrap calibration technique is proposed for constructing confidence intervals for the treatment effects. The method is illustrated with data from a longitudinal study comparing two diabetes drugs and a mammography screening trial comparing two treatments and a control
Some dilemmas for an account of neural representation: A reply to Poldrack
“The physics of representation” (Poldrack 2020) aims to (1) define the word “representation” as used in the neurosciences, (2) argue that such representations as described in neuroscience are related to and usefully illuminated by the representations generated by modern neural networks, and (3) establish that these entities are “representations in good standing”. We suggest that Poldrack succeeds in (1), exposes some tensions between the broad use of the term in neuroscience and the narrower class of entities that he identifies in the end, and between the meaning of “representation” in neuroscience and in psychology in (2), and fails in (3). This results in some hard choices: give up on the broad scope of the term in neuroscience (and thereby potentially opening a gap between psychology and neuroscience) or continue to embrace the broad, psychologically inflected sense of the term, and deny the entities generated by neural nets (and the brain) are representations in the relevant sense
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