201 research outputs found
On the number of outer automorphisms of the automorphism group of a right-angled Artin group
We show that there is no uniform upper bound on |Out(Aut(A))| when A ranges
over all right-angled Artin groups. This is in contrast with the cases where A
is free or free abelian: for all n, Dyer-Formanek and Bridson-Vogtmann showed
that Out(Aut(F_n)) = 1, while Hua-Reiner showed |Out(Aut(Z^n)| = |Out(GL(n,Z))|
< 5. We also prove the analogous theorem for Out(Out(A)). We establish our
results by giving explicit examples; one useful tool is a new class of graphs
called austere graphs
Lipid biomarkers in marine symbiotic systems
Fatty acid compositional analyses of various isolated symbiotic bacteria showed all species to be rich in 16:0, 16:1(n-7) and 18:1(n- 7) and depleted in PUFA. A variety of symbiont-containing marine invertebrates from a range of Iocations were than analysed and the majority were rich in 16:1(n-7|. 18:1(n-7) and non-methylene interrupted dienoic fatty acids(NMIDs), and depleted in polyunsaturated fatty acids (PUFA), so implying that symbiotic bacteria were a major source of nutrition for these animals. It was also considered that the NMIDs are produced by the host animal in response to a relative deficiency of conventional PUFA and an extensive bacterial production of 18:1(n-7). Members of the Thyasirid family contained, in addition to the symbiont-type fatty acids, substantial proportions of fatty acids normally associated with phytoplankton, namely 18:3(n-3) and 18:5(n-3). It was deduced from the fatty acid profiles that the Thyassirids undergo a mixotrophic mode of nutrition. Fatty acid analysis was applied to three geographically distinct methane seep sites where the major trophic processes were unclear. The results revealed that at one site the symbiotic relationship dominated while at the other sites, photosynthetic processes were of greater importance for the animals' nutrition. Finally, the study examined the incorporation of radioactive bicarbonate into the lipid classes of Lucinoaa borealia under a variety of environmental regime. It was concluded that both the fatty acid biomarker and the radioactive incorporation techniques together provide a powerful tool for the detailed examination of host-symbiont relationships in the marine environment
Prevalent low-grade dysplasia: the strongest predictor of malignant progression in Barrett's columnar-lined oesophagus
No abstract
Glatiramer acetate as a clinically and cost-effective treatment of relapsing multiple sclerosis over 10 years of use within the National Health Service: Final results from the UK Risk Sharing Scheme.
Background: The UK Risk Sharing Scheme (RSS) provided information on the effect of first-line multiple sclerosis (MS) disease-modifying treatments on long-term disability. Objective: The aim is to provide results specific to glatiramer acetate (GA; Copaxone®) from the final 10-year analysis of the RSS. Methods: A Markov model was used to assess clinical effectiveness measured as Expanded Disability Status Scale (EDSS) progression and utility loss. Untreated patients from the British Columbia MS cohort (1980-1995) were used as a 'virtual comparator' group. A separate Markov model assessed cost-effectiveness, based on a 50-year time horizon (with a 50% treatment waning effect imposed at 10 years) and using NHS list price (£513.95 per 28 days). Results were expressed in quality-adjusted life years (QALYs). Results: In total, 755 patients with relapsing-remitting MS (RRMS) received GA, with a mean follow-up of 7.1 (standard deviation 1.3) years. EDSS progression was reduced by 23% (progression ratio 76.7, 95% confidence interval [CI] 69.0-84.3) and utility loss by 39% (progression ratio 61.0, 95% CI 52.7-69.3) compared with no treatment. There was no persistent waning in GA treatment effect over time (EDSS: p = 0.093; utilities: p = 0.119). The cost per QALY was £17,841. Conclusion: GA had a beneficial effect on long-term disability and was a cost-effective treatment for RRMS
Neuromorphic liquid marbles with aqueous carbon nanotube cores
Neuromorphic computing devices attempt to emulate features of biological nervous systems through mimicking the properties of synapses, towards implementing the emergent properties of their counterparts, such as learning. Inspired by recent advances in the utilisation of liquid marbles (microlitre quantities of fluid coated in hydrophobic powder) for the creation of unconventional computing devices, we describe the development of liquid marbles with neuromorphic properties through the use of copper coatings and l.0mgml-1 carbon nanotube-containing fluid cores. Experimentation was performed through sandwiching the marbles between two cup-style electrodes and stimulating them with repeated DC pulses at 3.0 V. Our results demonstrate that 'entrainment∗ of a carbon nanotube filled-copper liquid marble via periodic pulses can cause their electrical resistance to rapidly switch between high to low resistance profiles, upon inverting the polarity of stimulation: The reduction in resistance between high and low profiles was approximately 88% after two rounds of entrainment. This effect was found to be reversible through reversion to the original stimulus polarity and was strengthened by repeated experimentation, as evidenced by a mean reduction in time to switching onset of 43%. These effects were not replicated in nanotube solutions not bound inside liquid marbles. Our electrical characterisation also reveals that nanotube-filled liquid marbles exhibit pinched loop hysteresis IV profiles consistent with the description of memristors. We conclude by discussing the applications of this technology to the development of unconventional computing devices and the study of emergent characteristics in biological neural tissue
Metastatic seminoma with isolated gastric metastases:a case report
Gastric metastases are a rare occurrence in patients with malignancy. In case reports of these arising from germ cell tumours, the majority were non-seminomatous germ cell tumours and had evidence of retroperitoneal involvement. We present a unique case of a 67-year-old man with metastatic testicular pure seminoma. He presented with dyspepsia and investigation found isolated metastases to the gastric mucosa and sub-mucosa from a right testicular primary. No lymph node involvement was identified. The patient was managed with curative intent with total gastrectomy and inguinal orchidectomy. To date, there is no evidence of disease recurrence
Interaction between healthcare professionals and parents is a key determinant of parental distress during childhood hospitalisation for respiratory syncytial virus infection (European RSV Outcomes Study [EROS])
Mapping outcomes of liquid marble collisions
© 2019 The Royal Society of Chemistry. Liquid marbles (LMs) have many promising roles in the ongoing development of microfluidics, microreactors, bioreactors, and unconventional computing. In many of these applications, the coalescence of two LMs is either required or actively discouraged, therefore it is important to study liquid marble collisions and establish parameters which enable the desired collision outcome. Recent reports on LM coalescence have focused on either two mobile LMs colliding, or an accelerating LM hitting a sessile LM with a backstop. A further possible scenario is the impact of a mobile LM against a non-supported static LM. This paper investigates such a collision, using high-speed videography for single-frame analysis. Multiple collisions were undertaken whilst varying the modified Weber number (We∗) and offset ratios (X∗). Parameter ranges of 1.0 0.25, and We∗ 1.55 resulted in 100% non-coalescence. Additionally, observations of LMs moving above a threshold velocity of 0.6 m s -1 have revealed a new and unusual deformation. Comparisons of the outcome of collisions whilst varying both the LM volume and the powder grain size have also been made, revealing a strong link. The results of this work provide a deeper understanding of LM coalescence, allowing improved control when designing future collision experiments
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