Decidable model-checking for a resource logic with production of resources

Several logics for expressing coalitional ability under resource bounds have been proposed and studied in the literature. Previous work has shown that if only consumption of resources is considered or the total amount of resources produced or consumed on any path in the system is bounded, then the model-checking problem for several standard logics, such as Resource-Bounded Coalition Logic (RB-CL) and Resource-Bounded Alternating-Time Temporal Logic (RB-ATL) is decidable. However, for coalition logics with unbounded resource production and consumption, only some undecidability results are known. In this paper, we show that the model-checking problem for RB-ATL with unbounded production and consumption of resources is decidable

Symbolic model checking for one-resource RB±ATL

RB±ATL is an extension of ATL where it is possible to model consumption and production of several resources by a set of agents. The model-checking problem for RB±ATL is known to be decidable. However the only available model-checking algorithm for RB±ATL uses a forward search of the state space, and hence does not have an efficient symbolic implementation. In this paper, we consider a fragment of RB±ATL, 1RB±ATL, that allows only one resource type. We give a symbolic model-checking algorithm for this fragment of RB±ATL, and evaluate the performance of an MCMAS-based implementation of the algorithm on an example problem that can be scaled to large state spaces

Neurospora teaching experiments.

Neurospora teaching experiments

New results for a photon-photon collider

We present new results from studies in progress on physics at a two-photon collider. We report on the sensitivity to top squark parameters of MSSM Higgs boson production in two-photon collisions; Higgs boson decay to two photons; radion production in models of warped extra dimensions; chargino pair production; sensitivity to the trilinear Higgs boson coupling; charged Higgs boson pair production; and we discuss the backgrounds produced by resolved photon-photon interactions.Comment: 17 pages, 15 figure

Conformation of the anterior segment in human myopia.

PURPOSE: Topography of the in vivo anterior segment is of relevance in understanding its role in myopia and in the development of ocular surgical procedures. Using 3D magnetic resonance (MR) images of the human eye, regional variations in surface area (SA) and bulbosity of four anterior segment regions were investigated in association with refractive status (Rx), axial length (AL) and total ocular volume (OV). METHODS: T2-weighted ocular MR images from 43 adults aged 18-40 years (mean ± SD; 28.65 ± 6.20) comprising 20 non-myopes (≥-0.50) 0.57 ± 1.38 and 23 myopes (<-0.50) -6.37 ± 4.23 MSE (D) were collected. 2D representations of each quadrant (superior-temporal [ST], superior-nasal [SN], inferior-temporal [IT] and inferior-nasal [IN]) of the anterior section (3.5-9 mm) were fitted with second-order polynomials. Polynomials were integrated and rotated about the x-axis to generate SA; dividing the SA by 4 provided relative quadrantial SA. The x2 coefficient provides indices of bulbosity. OV was derived from the 3D MRI scans. Rx and AL were measured using cycloplegic autorefraction and the Zeiss IOLMaster, respectively. One- and two-way repeated-measures ANCOVAs tested differences in SA and bulbosity for Rx, gender, ethnicity and age. Pearson's correlation coefficient tested the relationship between MRI-derived metrics and biometry. RESULTS: Significant differences in SA were observed between quadrants (p < 0.001) with differences between ST versus IN, IN versus IT and SN versus IT. An interaction effect (p = 0.01) for Rx suggested smaller temporal (ST and IT) and larger nasal (SN and IN) SA in myopes. AL and myopic Rx were negative correlated (p < 0.05) with SA at IN, SN and IT. OV was significantly associated with SA at ST. Bulbosity showed no regional differences nor an effect of AL or Rx. CONCLUSION: Significant regional variation in SA exists across the anterior segment that is modulated by Rx and AL. It is unclear whether these structural characteristics are a precursor or consequence of myopia and may warrant investigation when developing biomechanical interventions

Field-dependent dynamics of the Anderson impurity model

Single-particle dynamics of the Anderson impurity model in the presence of a magnetic field $H$ are considered, using a recently developed local moment approach that encompasses all energy scales, field and interaction strengths. For strong coupling in particular, the Kondo scaling regime is recovered. Here the frequency ($\omega/\omega_{\rm K}$) and field ($H/\omega_{\rm K}$) dependence of the resultant universal scaling spectrum is obtained in large part analytically, and the field-induced destruction of the Kondo resonance investigated. The scaling spectrum is found to exhibit the slow logarithmic tails recently shown to dominate the zero-field scaling spectrum. At the opposite extreme of the Fermi level, it gives asymptotically exact agreement with results for statics known from the Bethe ansatz. Good agreement is also found with the frequency and field-dependence of recent numerical renormalization group calculations. Differential conductance experiments on quantum dots in the presence of a magnetic field are likewise considered; and appear to be well accounted for by the theory. Some new exact results for the problem are also established

Local quantum phase transition in the pseudogap Anderson model: scales, scaling and quantum critical dynamics

The pseudogap Anderson impurity model provides a paradigm for understanding local quantum phase transitions, in this case between generalised fermi liquid and degenerate local moment phases. Here we develop a non-perturbative local moment approach to the generic asymmetric model, encompassing all energy scales and interaction strengths and leading thereby to a rich description of the problem. We investigate in particular underlying phase boundaries, the critical behaviour of relevant low-energy scales, and single-particle dynamics embodied in the local spectrum. Particular attention is given to the resultant universal scaling behaviour of dynamics close to the transition in both the GFL and LM phases, the scale-free physics characteristic of the quantum critical point itself, and the relation between the two.Comment: 39 pages, 19 figure

Diffusion, Cell Mobility, and Bandlimited Functions

The mechanism by which leukocytes steer toward a chemical attractant is not fully resolved. Experimental data suggest that these cells detect differences in concentration of chemoattractant over their surface and walk up the gradient. The problem has been considered theoretically only in stationary media, where the distribution of attractant is determined solely by diffusion. Experimentally, bulk flow has been allowed only unintentionally. Since bulk flow is characteristic of real systems, we examine a simple two-dimensional model incorporating both diffusion and an additional drift. The latter problem leads to an integral equation which is central also in the study of weighted Hilbert spaces of bandlimited functions. We find asymptotic expressions for the required solution by a Wiener-Hopf method adapted to a finite interval. We conclude that, without drift, the concentration does not vary detectably around the cell, but that drift inceases this variation substantially. Thus over model suggests that drift may play an important role in the cell\u27s chemotactic response

What do we really know about the appropriateness of radiation emitting imaging for low back pain in primary and emergency care? A systematic review and meta-analysis of medical record reviews

Background Since 2000, guidelines have been consistent in recommending when diagnostic imaging for low back pain should be obtained to ensure patient safety and reduce unnecessary tests. This systematic review and meta-analysis was conducted to determine the pooled proportion of CT and x-ray imaging of the lumbar spine that were considered appropriate in primary and emergency care. Methods Pubmed, CINAHL, The Cochrane Database of Systematic Reviews and Embase were searched for synonyms of “low back pain”, “guidelines”, and “adherence” that were published after 2000. Titles, abstracts, and full texts were reviewed for inclusion with forward and backward tracking on included studies. Included studies had data extracted and synthesized. Risk of bias was performed on all studies, and GRADE was performed on included studies that provided data on CT and x-ray separately. A random effect, single proportion meta-analysis model was used. Results Six studies were included in the descriptive synthesis, and 5 studies included in the meta-analysis. Five of the 6 studies assessed appropriateness of x-rays; two of the six studies assessed appropriateness of CTs. The pooled estimate for appropriateness of x-rays was 43% (95% CI: 30%, 56%) and the pooled estimate for appropriateness of CTs was 54% (95% CI: 51%, 58%). Studies did not report adequate information to fulfill the RECORD checklist (reporting guidelines for research using observational data). Risk of bias was high in 4 studies, moderate in one, and low in one. GRADE for x-ray appropriateness was low-quality and for CT appropriateness was very-low-quality. Conclusion While this study determined a pooled proportion of appropriateness for both x-ray and CT imaging for low back pain, there is limited confidence in these numbers due to the downgrading of the evidence using GRADE. Further research on this topic is needed to inform our understanding of x-ray and CT appropriateness in order to improve healthcare systems and decrease patient harms