2,109 research outputs found

    Complete graphs whose topological symmetry groups are polyhedral

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    We determine for which mm, the complete graph KmK_m has an embedding in S3S^3 whose topological symmetry group is isomorphic to one of the polyhedral groups: A4A_4, A5A_5, or S4S_4.Comment: 27 pages, 12 figures; v.2 and v.3 include minor revision

    Automorphism groups of countable algebraically closed graphs and endomorphisms of the random graph

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    We establish links between countable algebraically closed graphs and the endomorphisms of the countable universal graph RR. As a consequence we show that, for any countable graph Γ\Gamma, there are uncountably many maximal subgroups of the endomorphism monoid of RR isomorphic to the automorphism group of Γ\Gamma. Further structural information about End RR is established including that Aut Γ\Gamma arises in uncountably many ways as a Sch\"{u}tzenberger group. Similar results are proved for the countable universal directed graph and the countable universal bipartite graph.Comment: Minor revision following referee's comments. 27 pages, 3 figure

    Medical treatment of dystonia

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    Abstract Therapeutic strategies in dystonia have evolved considerably in the past few decades. Three major treatment modalities include oral medications, botulinum toxin injections and surgical therapies, particularly deep brain stimulation. Although there has been a tremendous interest in the later two modalities, there are relatively few recent reviews of oral treatment. We review the medical treatment of dystonia, focusing on three major neurotransmitter systems: cholinergic, GABAergic and dopaminergic. We also provide a practical guide to medication selection, therapeutic strategy and unmet needs

    Vertex-primitive groups and graphs of order twice the product of two distinct odd primes

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    A non-Cayley number is an integer n for which there exists a vertex-transitive graph on n vertices which is not a Cayley graph. In this paper, we complete the determination of the non-Cayley numbers of the form 2pq, where p, q are distinct odd primes. Earlier work of Miller and the second author had dealt with all such numbers corresponding to vertex-transitive graphs admitting an imprimitive subgroup of automorphisms. This paper deals with the primitive case. First the primitive permutation groups of degree 2pq are classified. This depends on the finite simple group classification. Then each of these groups G is examined to determine whether there are any non-Cayley graphs which admit G as a vertex-primitive subgroup of automorphisms, and admit no imprimitive subgroups. The outcome is that 2pq is a non-Cayley number, where

    Automatically generating streamlined constraint models with ESSENCE and CONJURE

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    Streamlined constraint reasoning is the addition of uninferred constraints to a constraint model to reduce the search space, while retaining at least one solution. Previously, effective streamlined models have been constructed by hand, requiring an expert to examine closely solutions to small instances of a problem class and identify regularities. We present a system that automatically generates many conjectured regularities for a given Essence specification of a problem class by examining the domains of decision variables present in the problem specification. These conjectures are evaluated independently and in conjunction with one another on a set of instances from the specified class via an automated modelling tool-chain comprising of Conjure, Savile Row and Minion. Once the system has identified effective conjectures they are used to generate streamlined models that allow instances of much larger scale to be solved. Our results demonstrate good models can be identified for problems in combinatorial design, Ramsey theory, graph theory and group theory - often resulting in order of magnitude speed-ups.Postprin

    Lance-Adams Syndrome

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    Lance-Adams syndrome (LAS) is a rare complication of successful cardiopulmonary resuscitation and is often accompanied by action myoclonus. LAS is seen in patients who have undergone a cardiorespiratory arrest, later regained consciousness, and then developed myoclonus days or weeks after the event. Less than 150 cases of LAS have been reported in the worldwide medical literature. Here, we present a 32-year-old man who suffered from myoclonus after hypoxic brain damage due to hanging himself. This case was diagnosed as Lance-Adams syndrome according to a history of hypoxic brain damage, the clinical features, and the neuroimages such as brain SPECT. Making an early diagnosis and properly managing LAS is positively related to improving the patient's functional outcome. If patients have posthypoxic myoclonus after successful cardiopulmonary resuscitation, we should consider the diagnosis of LAS and initiate a proper rehabilitation program

    Mice That Express Human Interleukin-8 Have Increased Mobilization of Immature Myeloid Cells, Which Exacerbates Inflammation and Accelerates Colon Carcinogenesis

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    Background & Aims Interleukin (IL)-8 has an important role in initiating inflammation in humans, attracting immune cells such as neutrophils through their receptors CXCR1 and CXCR2. IL-8 has been proposed to contribute to chronic inflammation and cancer. However, mice do not have the IL-8 gene, so human cancer cell lines and xenograft studies have been used to study the role of IL-8 in colon and gastric carcinogenesis. We generated mice that carry a bacterial artificial chromosome that encompasses the entire human IL-8 gene, including its regulatory elements (IL-8Tg mice). Methods We studied the effects of IL-8 expression in APCmin[superscript +/−] mice and IL-8Tg mice given azoxymethane and dextran sodium sulfate (DSS). We also examined the effects of IL-8 expression in gastric cancer in INS-GAS mice that overexpress gastrin and IL-8Tg mice infected with Helicobacter felis. Results In IL-8Tg mice, expression of human IL-8 was controlled by its own regulatory elements, with virtually no messenger RNA or protein detectable under basal conditions. IL-8 was strongly up-regulated on systemic or local inflammatory stimulation, increasing mobilization of immature CD11b[superscript +]Gr-1[superscript +] myeloid cells (IMCs) with thioglycolate-induced peritonitis, DSS-induced colitis, and H. felis–induced gastritis. IL-8 was increased in colorectal tumors from patients and IL-8Tg mice compared with nontumor tissues. IL-8Tg mice developed more tumors than wild-type mice following administration of azoxymethane and DSS. Expression of IL-8 increased tumorigenesis in APCmin[superscript +/−] mice compared with APCmin[superscript +/−] mice that lack IL-8; this was associated with increased numbers of IMCs and angiogenesis in the tumors. Conclusions IL-8 contributes to gastrointestinal carcinogenesis by mobilizing IMCs and might be a therapeutic target for gastrointestinal cancers
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