Reconfiguration on sparse graphs

A vertex-subset graph problem Q defines which subsets of the vertices of an input graph are feasible solutions. A reconfiguration variant of a vertex-subset problem asks, given two feasible solutions S and T of size k, whether it is possible to transform S into T by a sequence of vertex additions and deletions such that each intermediate set is also a feasible solution of size bounded by k. We study reconfiguration variants of two classical vertex-subset problems, namely Independent Set and Dominating Set. We denote the former by ISR and the latter by DSR. Both ISR and DSR are PSPACE-complete on graphs of bounded bandwidth and W[1]-hard parameterized by k on general graphs. We show that ISR is fixed-parameter tractable parameterized by k when the input graph is of bounded degeneracy or nowhere-dense. As a corollary, we answer positively an open question concerning the parameterized complexity of the problem on graphs of bounded treewidth. Moreover, our techniques generalize recent results showing that ISR is fixed-parameter tractable on planar graphs and graphs of bounded degree. For DSR, we show the problem fixed-parameter tractable parameterized by k when the input graph does not contain large bicliques, a class of graphs which includes graphs of bounded degeneracy and nowhere-dense graphs

Handwritten digit recognition by bio-inspired hierarchical networks

The human brain processes information showing learning and prediction abilities but the underlying neuronal mechanisms still remain unknown. Recently, many studies prove that neuronal networks are able of both generalizations and associations of sensory inputs. In this paper, following a set of neurophysiological evidences, we propose a learning framework with a strong biological plausibility that mimics prominent functions of cortical circuitries. We developed the Inductive Conceptual Network (ICN), that is a hierarchical bio-inspired network, able to learn invariant patterns by Variable-order Markov Models implemented in its nodes. The outputs of the top-most node of ICN hierarchy, representing the highest input generalization, allow for automatic classification of inputs. We found that the ICN clusterized MNIST images with an error of 5.73% and USPS images with an error of 12.56%

9.7 um Silicate Features in AGNs: New Insights into Unification Models

We describe observations of 9.7 um silicate features in 97 AGNs, exhibiting a wide range of AGN types and of X-ray extinction toward the central nuclei. We find that the strength of the silicate feature correlates with the HI column density estimated from fitting the X-ray data, such that low HI columns correspond to silicate emission while high columns correspond to silicate absorption. The behavior is generally consistent with unification models where the large diversity in AGN properties is caused by viewing-angle-dependent obscuration of the nucleus. Radio-loud AGNs and radio-quiet quasars follow roughly the correlation between HI columns and the strength of the silicate feature defined by Seyfert galaxies. The agreement among AGN types suggests a high-level unification with similar characteristics for the structure of the obscuring material. We demonstrate the implications for unification models qualitatively with a conceptual disk model. The model includes an inner accretion disk (< 0.1 pc in radius), a middle disk (0.1-10 pc in radius) with a dense diffuse component and with embedded denser clouds, and an outer clumpy disk (10-300 pc in radius).Comment: Accepted for publication in ApJ, 14 pages, 5 figures. The on-line table is available at http://cztsy.as.arizona.edu/~yong/silicate_tab1.pd

Mixed-state quasiparticle transport in high-T_c cuprates: localization by magnetic field

Theory of quasiparticle transport in the mixed state of a d-wave superconductor is developed under the assumption of disordered vortex array. A novel universal regime is identified at fields above H*= c*H_{c2}(T/T_c)^2, characterized by a field-independent longitudinal thermal conductivity. It is argued that this behavior is responsible for the high-field plateau in the thermal conductivity experimentally observed in cuprates by Krishana, Ong and co-workers.Comment: 4 pages REVTeX + 1 PostScript figure. Final version to appear in PRL. Several changes in response to referee comments. For related work and info visit http://www.pha.jhu.edu/~fran

Patient and Public Involvement Refines the Design of ProtOeus: A Proposed Phase II Trial of Proton Beam Therapy in Oesophageal Cancer

Background: Neoadjuvant chemoradiotherapy for oesophageal cancer significantly improves overall survival but is associated with severe post-operative complications. Proton beam therapy may reduce these toxicities by sparing normal tissues compared with standard radiotherapy. ProtOeus is a proposed randomised phase II study of neoadjuvant chemoradiotherapy in oesophageal cancer that compares proton beam therapy to standard radiotherapy techniques. As proton beam therapy services are often centralised in academic centres in major cities, proton beam therapy trials raise distinct challenges including patient acceptance of travelling for proton beam therapy, coordination of treatments with local centres and ensuring equity of access for patients. Methods: Focus groups were held early in the trial development process to establish patients’ views on the trial proposal. Topics discussed include perception of proton beam therapy, patient acceptability of the trial pathway and design, patient-facing materials, and common clinical scenarios. Focus groups were led by the investigators and facilitated by patient involvement teams from the institutions who are involved in this research. Responses for each topic were analysed, and fed back to the trial’s development group. Results: Three focus groups were held in separate locations in the UK (Manchester, Cardiff, Wigan). Proton beam therapy was perceived as superior to standard radiotherapy making the trial attractive. Patients felt strongly that travel costs should be reimbursed to ensure equity of access to proton beam therapy. They were very supportive of a shorter treatment schedule and felt that toxicity reduction was the most important endpoint. Discussion and Conclusions: Incorporating patient views early in the trial development process resulted in significant trial design refinements including travel/accommodation provisions, choice of primary endpoint, randomisation ratio and fractionation schedule. Focus groups are a reproducible and efficient method of incorporating the patient and public voice into research

Anesthesia for intra-articular corticosteroid injections in juvenile idiopathic arthritis: A survey of pediatric rheumatologists

<p>Abstract</p> <p>Objective</p> <p>To determine the methods of anesthesia currently being used by pediatric rheumatologists when performing intra-articular corticosteroid injections (IACI).</p> <p>Study design</p> <p>A questionnaire was emailed to all members of the Childhood Arthritis & Rheumatology Research Alliance, a pediatric rheumatology research network in North America. The questionnaire consisted of 11 questions ranging from procedure technique, treatments prescribed for topical anesthesia and oral analgesia, and factors that might affect procedural pain.</p> <p>Results</p> <p>Seventy-four of 161 physicians (46%) responded to the questionnaire. On average, each physician injected 33 children (median 25, range 1-160) and 43 joints (median 30, range 1-150) yearly. Local anesthesia was used in children on average ≥ 8 years (range 2-16 years), with general anesthesia being more frequently used for younger children. All respondents used local anesthesia. The most commonly used methods of local anesthesia were EMLA^®cream plus subcutaneous lidocaine (58.8%), ethyl chloride spray only (39.7%), EMLA^®cream only (33.8%), subcutaneous lidocaine only (25%), and lidocaine iontophoresis only (11.8%). Buffering of the lidocaine was routinely done only 7.4% of the time.</p> <p>Conclusion</p> <p>Although pediatric rheumatologists in North America perform IACI on a large number of patients each year, a wide variety of methods are used to deliver local anesthesia with no accepted standard of care. More studies are needed to determine the optimal method of local anesthesia delivery to minimize pain associated with IACI.</p

Application of realistic effective interactions to the structure of the Zr isotopes

We calculate the low-lying spectra of the zirconium isotopes Z=40 with neutron numbers from N=52 to N=60 using the 1p1/20g9/2 proton and 2s1d0g7/20h11/2 neutron sub-shells to define the model space. Effective proton-proton, neutron--neutron and proton-neutron interactions have been derived using 88Sr as closed core and employing perturbative many-body techniques. The starting point is the nucleon-nucleon potential derived from modern meson exchange models. The comprehensive shell-model calculation performed in this work provides a qualitative reproduction of essential properties such as the sub-shell closures in 96Zr and 98Zr.Comment: To appear in Phys Rev C, june 2000, 8 figs, Revtex latex styl

Vortex vs spinning string: Iordanskii force and gravitational Aharonov-Bohm effect

We discuss the transverse force acting on the spinning cosmic string, moving in the background matter. It comes from the gravitational Aharonov-Bohm effect and corresponds to the Iordanskii force acting on the vortex in superfluids, when the vortex moves with respect to the normal component of the liquid.Comment: Latex file, 9 pages, no figures, references are added, version submitted to JETP Let