Refining the characterization of projective graphs

Archdeacon showed that the class of graphs embeddable in the projective plane is characterized by a set of 35 excluded minors. Robertson, Seymour and Thomas in an unpublished result found the excluded minors for the class of k-connected graphs embeddable on the projective plane for k = 1,2,3. We give a short proof of that result and then determine the excluded minors for the class of internally 4-connected projective graphs. Hall showed that a 3-connected graph diff_x000B_erent from K5 is planar if and only if it has K3,3 as a minor. We provide two analogous results for projective graphs. For any minor-closed class of graphs C, we say that a set of k-connected graphs E disjoint from C is a k-connected excludable set for C if all but a _x000C_finite number of k-connected graphs not in C have a minor in E. Hall\u27s result is equivalent to saying that {K3,3} is a 3-connected excludable set for the class of planar graphs. We classify all minimal 3-connected excludable sets and fi_x000C_nd one minimal internally 4-connected excludable set for the class of projective graphs. In doing so, we also prove strong splitter theorems for 3-connected and internally 4-connected graphs that could have application to other problems of this type

Internally 4-connected projective-planar graphs

Archdeacon proved that projective-planar graphs are characterized by 35 excluded minors. Using this result we show that internally 4-connected projective-planar graphs are characterized by 23 internally 4-connected excluded minors. © 2014 Elsevier Inc

Bandwidth of trees of diameter at most 4

For a graph G, let γ:V(G)→1,⋯,|V(G)| be a one-to-one function. The bandwidth of γ is the maximum of |γ(u)-γ(v)| over uv∈E(G). The bandwidth of G, denoted b(G), is the minimum bandwidth over all embeddings γ, b(G)=min γmax|γ(u)-γ(v) |:uv∈E(G). In this paper, we show that the bandwidth computation problem for trees of diameter at most 4 can be solved in polynomial time. This naturally complements the result computing the bandwidth for 2-caterpillars. © 2012 Elsevier B.V. All rights reserved

Positron emission tomography measures of benzodiazepine receptors in Huntington's disease

We performed positron emission tomographic (PET) measurements of the regional distribution volume of benzodiazepine receptors and regional glucose metabolism in 6 drug-free patients with early Huntington's disease following injection of [ 11 C] flumazenil, a nonsubtype selective central benzodiazepine receptor antagonist, and 18 F-2-fluoro-2-deoxy- D -glucose, respectively. Flumazenil data were analyzed with a recently developed two-compartment, two-parameter tracer kinetic model. Benzodiazepine receptor density is related to distribution volume for flumazenil. In comparison with a group of healthy volunteers, benzodiazepine receptor density was significantly decreased in the caudate nucleus. Glucose metabolism was significantly reduced not only in the caudate nucleus but also in the putamen and thalamus. The changes in benzodiazepine receptor density observed in the caudate nucleus are commensurate with data obtained in postmortem autoradiographic studies of receptor density. Based on such postmortem studies we also anticipated changes in putamen and thalamic benzodiazepine receptor density. However, relatively little is known on receptor changes in early Huntington's disease, because the autoradiographic data available were obtained mostly in patients with advanced disease. The decreased glucose metabolism in the caudate and putamen agrees well with previously published results of PET studies, whereas metabolic impairment of the thalamus has not yet been described in Huntington's disease. The present study suggests that regional metabolism and Γ-aminobutyric acid (GABA)-benzodiazepine receptor changes in subcortical structures of patients with early Huntington's disease do not occur with the same time course: Caudate benzodiazepine receptor density is already severely impaired when other subcortical structures reveal only minor abnormalities. Impairment of neuronal metabolism seems to predate GABA/benzodiazepine receptor changes since the putamen and thalamus demonstrate metabolic impairment without detectable loss of benzodiazepine receptor density.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50353/1/410340114_ftp.pd

Population Health Solutions for Assessing Cognitive Impairment in Geriatric Patients.

In December 2017, the National Academy of Neuropsychology convened an interorganizational Summit on Population Health Solutions for Assessing Cognitive Impairment in Geriatric Patients in Denver, Colorado. The Summit brought together representatives of a broad range of stakeholders invested in the care of older adults to focus on the topic of cognitive health and aging. Summit participants specifically examined questions of who should be screened for cognitive impairment and how they should be screened in medical settings. This is important in the context of an acute illness given that the presence of cognitive impairment can have significant implications for care and for the management of concomitant diseases as well as pose a major risk factor for dementia. Participants arrived at general principles to guide future screening approaches in medical populations and identified knowledge gaps to direct future research. Key learning points of the summit included: recognizing the importance of educating patients and healthcare providers about the value of assessing current and baseline cognition;emphasizing that any screening tool must be appropriately normalized and validated in the population in which it is used to obtain accurate information, including considerations of language, cultural factors, and education; andrecognizing the great potential, with appropriate caveats, of electronic health records to augment cognitive screening and tracking of changes in cognitive health over time

Developmental pathways to autism: a review of prospective studies of infants at risk

Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders characterized by impairments in social interaction and communication, and the presence of restrictive and repetitive behaviors. Symptoms of ASD likely emerge from a complex interaction between pre-existing neurodevelopmental vulnerabilities and the child's environment, modified by compensatory skills and protective factors. Prospective studies of infants at high familial risk for ASD (who have an older sibling with a diagnosis) are beginning to characterize these developmental pathways to the emergence of clinical symptoms. Here, we review the range of behavioral and neurocognitive markers for later ASD that have been identified in high-risk infants in the first years of life. We discuss theoretical implications of emerging patterns, and identify key directions for future work, including potential resolutions to several methodological challenges for the field. Mapping how ASD unfolds from birth is critical to our understanding of the developmental mechanisms underlying this disorder. A more nuanced understanding of developmental pathways to ASD will help us not only to identify children who need early intervention, but also to improve the range of interventions available to them

The impact of motor development on typical and atypical social cognition and language: a systematic review

Background: Motor development allows infants to gain knowledge of the world but its vital role in social development is often ignored. Method: A systematic search for papers investigating the relationship between motor and social skills was conducted, including research in typical development and in Developmental Coordination Disorder, Autism Spectrum Disorders and Specific Language Impairment. Results: The search identified 43 studies, many of which highlighted a significant relationship between motor skills and the development of social cognition, language and social interactions. Conclusions: This complex relationship requires more attention from researchers and practitioners, allowing the development of more tailored intervention techniques for those at risk of motor, social and language difficulties

Improvement of local budget filling

This chapter describes the biological removal of sulphur compounds from gas streams. First, an overview is given of the toxicity of sulphur compounds to animals and humans whereafter biological and industrial formation routes for (organic) sulphur compounds are given. Microbial degradation routes of volatile organic sulphur compounds under both aerobic and anaerobic conditions are presented. Finally, the most commonly applied processes for sulphur removal from gaseous streams are discussed and an overview is given of operating experiences for biological gas treatment systems. The chapter concludes with some remarks on future developments