7,635 research outputs found

    On Atkin and Swinnerton-Dyer Congruence Relations (2)

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    In this paper we give an example of a noncongruence subgroup whose three-dimensional space of cusp forms of weight 3 has the following properties. For each of the four residue classes of odd primes modulo 8 there is a basis whose Fourier coefficients at infinity satisfy a three-term Atkin and Swinnerton-Dyer congruence relation, which is the pp-adic analogue of the three-term recursion satisfied by the coefficients of classical Hecke eigen forms. We also show that there is an automorphic LL-function over Q\mathbb Q whose local factors agree with those of the ll-adic Scholl representations attached to the space of noncongruence cusp forms.Comment: Last version, to appear on Math Annale

    An Age Old Problem? Estimating the Impact of Dementia on Past Human Populations.

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    OBJECTIVE: To model the impact of dementia on past societies. METHOD: We consider multiple lines of evidence indicating elderly individuals to have been more common throughout the past than is frequently accepted. We then apply known dementia incidence/prevalence rates to plausible assumptions of past population structures to suggest prevalence in the past. RESULTS: Dementia prevalence in premodern societies is likely to have been around 5% of the rate seen in modern, developed countries but with a total past incidence running into billions. DISCUSSION: Dementia is often seen as a "modern" challenge that humans have not had to contend with before. We argue that this condition has had considerably greater effects than previously envisaged and is a challenge that humans have already withstood successfully, on one hand at a lower incidence but on the other without the considerable clinical, technological, and social advances that have been made in recent times

    The trade-off between taxi time and fuel consumption in airport ground movement

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    Environmental impact is a very important agenda item in many sectors nowadays, which the air transportation sector is also trying to reduce as much as possible. One area which has remained relatively unexplored in this context is the ground movement problem for aircraft on the airport’s surface. Aircraft have to be routed from a gate to a runway and vice versa and it is still unknown whether fuel burn and environmental impact reductions will best result from purely minimising the taxi times or whether it is also important to avoid multiple acceleration phases. This paper presents a newly developed multi-objective approach for analysing the trade-off between taxi time and fuel consumption during taxiing. The approach consists of a combination of a graph-based routing algorithm and a population adaptive immune algorithm to discover different speed profiles of aircraft. Analysis with data from a European hub airport has highlighted the impressive performance of the new approach. Furthermore, it is shown that the trade-off between taxi time and fuel consumption is very sensitive to the fuel-related objective function which is used

    Lessons from building an automated pre-departure sequencer for airports

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    Commercial airports are under increasing pressure to comply with the Eurocontrol collaborative decision making (CDM) initiative, to ensure that information is passed between stakeholders, integrate automated decision support or make predictions. These systems can also aid effective operations beyond the airport by communicating scheduling decisions to other relevant parties, such as Eurocontrol, for passing on to downstream airports and enabling overall airspace improvements. One of the major CDM components is aimed at producing the target take-off times and target startup-approval times, i.e. scheduling when the aircraft should push back from the gates and start their engines and when they will take off. For medium-sized airports, a common choice for this is a “pre-departure sequencer” (PDS). In this paper, we describe the design and requirements challenges which arose during our development of a PDS system for medium sized international airports. Firstly, the scheduling problem is highly dynamic and event driven. Secondly, it is important to end-users that the system be predictable and, as far as possible, transparent in its operation, with decisions that can be explained. Thirdly, users can override decisions, and this information has to be taken into account. Finally, it is important that the system is as fair as possible for all users of the airport, and the interpretation of this is considered here. Together, these factors have influenced the design of the PDS system which has been built to work within an existing large system which is being used at many airport

    Quest for certainty regarding early discharge in paediatric low-risk febrile neutropenia : a multicentre qualitative focus group discussion study involving patients, parents and healthcare professionals in the UK

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    OBJECTIVES: A systematic review of paediatric low-risk febrile neutropenia found that outpatient care is safe, with low rates of treatment failure. However, this review, and a subsequent meta-ethnography, suggested that early discharge of these patients may not be acceptable to key stakeholders. This study aimed to explore experiences and perceptions of patients, parents and healthcare professionals involved in paediatric febrile neutropenia care in the UK. SETTING: Three different centres within the UK, purposively selected from a national survey on the basis of differences in their service structure and febrile neutropenia management. PARTICIPANTS: Thirty-two participants were included in eight focus group discussions. PRIMARY OUTCOMES: Experiences and perceptions of paediatric febrile neutropenia care, including possible future reductions in therapy. RESULTS: Participants described a quest for certainty, in which they attempted to balance the uncertainty involved in understanding, expressing and negotiating risk with the illusion of certainty provided by strict protocols. Participants assessed risk using both formal and informal stratification tools, overlaid with emotional reactions to risk and experiences of risk within other situations. The benefits of certainty provided by protocols were counterbalanced by frustration at their strict constraints. The perceived benefits and harms of previous inpatient care informed participants' appraisals of future treatment strategies. CONCLUSIONS: This study highlighted the previously underestimated harms of admission for febrile neutropenia and the paternalistic nature of decision making, along with the frustrations and challenges for all parties involved in febrile neutropenia care. It demonstrates how the same statistics, generated by systematic reviews, can be used by key stakeholders to interpret risk differently, and how families in particular can view the harms of therapeutic options as different from the outcomes used within the literature. It justifies a reassessment of current treatment strategies for these children and further exploration of the potential to introduce shared decision making

    Using a hypothetical scenario to assess public preferences for colorectal surveillance following screening-detected, intermediate-risk adenomas: annual home-based stool test vs. triennial colonoscopy

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    Background To assess public preferences for colorectal cancer (CRC) surveillance tests for intermediate-risk adenomas, using a hypothetical scenario. Methods Adults aged 45–54 years without CRC were identified from three General Practices in England (two in Cumbria, one in London). A postal survey was carried out during a separate study on preferences for different first-line CRC screening modalities (non- or full-laxative computed tomographic colonography, flexible sigmoidoscopy, or colonoscopy). Individuals were allocated at random to receive a pack containing information on one first-line test, and a paragraph describing CRC surveillance recommendations for people who are diagnosed with intermediate-risk adenomas during screening. All participants received a description of two surveillance options: annual single-sample, home-based stool testing (consistent with Faecal Immunochemical Tests; FIT) or triennial colonoscopy. Invitees were asked to imagine they had been diagnosed with intermediate-risk adenomas, and then complete a questionnaire on their surveillance preferences. Results 22.1 % (686/3,100) questionnaires were returned. 491 (15.8 %) were eligible for analysis. The majority of participants stated a surveillance preference for the stool test over colonoscopy (60.8 % vs 31.0 %; no preference: 8.1 %; no surveillance: 0.2 %). Women were more likely to prefer the stool test than men (66.7 % vs. 53.6 %; p = .011). The primary reason for preferring the stool test was that it would be done more frequently. The main reason to prefer colonoscopy was its superiority at finding polyps. Conclusions A majority of participants stated a preference for a surveillance test resembling FIT over colonoscopy. Future research should test whether this translates to greater adherence in a real surveillance setting
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