4,367 research outputs found

    Chromatic Ramsey number of acyclic hypergraphs

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    Suppose that TT is an acyclic rr-uniform hypergraph, with r≥2r\ge 2. We define the (tt-color) chromatic Ramsey number χ(T,t)\chi(T,t) as the smallest mm with the following property: if the edges of any mm-chromatic rr-uniform hypergraph are colored with tt colors in any manner, there is a monochromatic copy of TT. We observe that χ(T,t)\chi(T,t) is well defined and ⌈Rr(T,t)−1r−1⌉+1≤χ(T,t)≤∣E(T)∣t+1\left\lceil {R^r(T,t)-1\over r-1}\right \rceil +1 \le \chi(T,t)\le |E(T)|^t+1 where Rr(T,t)R^r(T,t) is the tt-color Ramsey number of HH. We give linear upper bounds for χ(T,t)\chi(T,t) when T is a matching or star, proving that for r≥2,k≥1,t≥1r\ge 2, k\ge 1, t\ge 1, χ(Mkr,t)≤(t−1)(k−1)+2k\chi(M_k^r,t)\le (t-1)(k-1)+2k and χ(Skr,t)≤t(k−1)+2\chi(S_k^r,t)\le t(k-1)+2 where MkrM_k^r and SkrS_k^r are, respectively, the rr-uniform matching and star with kk edges. The general bounds are improved for 33-uniform hypergraphs. We prove that χ(Mk3,2)=2k\chi(M_k^3,2)=2k, extending a special case of Alon-Frankl-Lov\'asz' theorem. We also prove that χ(S23,t)≤t+1\chi(S_2^3,t)\le t+1, which is sharp for t=2,3t=2,3. This is a corollary of a more general result. We define H[1]H^{[1]} as the 1-intersection graph of HH, whose vertices represent hyperedges and whose edges represent intersections of hyperedges in exactly one vertex. We prove that χ(H)≤χ(H[1])\chi(H)\le \chi(H^{[1]}) for any 33-uniform hypergraph HH (assuming χ(H[1])≥2\chi(H^{[1]})\ge 2). The proof uses the list coloring version of Brooks' theorem.Comment: 10 page

    "Boring formal methods" or "Sherlock Holmes deduction methods"?

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    This paper provides an overview of common challenges in teaching of logic and formal methods to Computer Science and IT students. We discuss our experiences from the course IN3050: Applied Logic in Engineering, introduced as a "logic for everybody" elective course at at TU Munich, Germany, to engage pupils studying Computer Science, IT and engineering subjects on Bachelor and Master levels. Our goal was to overcome the bias that logic and formal methods are not only very complicated but also very boring to study and to apply. In this paper, we present the core structure of the course, provide examples of exercises and evaluate the course based on the students' surveys.Comment: Preprint. Accepted to the Software Technologies: Applications and Foundations (STAF 2016). Final version published by Springer International Publishing AG. arXiv admin note: substantial text overlap with arXiv:1602.0517

    Tyrosine kinase inhibitors for the therapy of anaplastic thyroid cancer

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    Anaplastic thyroid cancer (ATC) is often incurable so new therapeutic approaches are needed. Tyrosine kinases inhibitors (such as imanitib, sunitinib or sorafenib) are under evaluation for the treatment of ATC. Other vascular disrupting agents, such as combretastatin A4 phosphate, and antiangiogenic agents, such as aplidin, PTK787/ZK222584 and human VEGF monoclonal antibodies (bevacizumab, cetuximab), have been evaluated. Small-molecule adenosine triphosphate competitive inhibitors directed intracellularly at EGFRs tyrosine kinase, such as erlotinib or gefitinib, are also studied. Furthermore, new molecules have been shown to be active against ATC, such as CLM94 and CLM3. However, more research is needed to finally identify therapies able to control and to cure this disease

    No good surprises: intending lecturers' preconceptions and initial experiences of further education

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    Current initiatives to promote lifelong learning and a broader inclusiveness in post-16 education have focused attention on further education (FE). The article examines the experiences and reactions of 41 intending lecturers studying full-time for a Postgraduate Certificate in Further Education and Training (PGCET), as they enter FE colleges on teaching practice and encounter FE students for the first time. It argues that the sector may have something to learn from the contrast between these intending lecturers' expectations and their subsequent experiences, and that attempts to address problems which are endemic within the current FE sector by initiatives to improve teacher competence, such as the Further Education National Training Organisation (FENTO)'s recently introduced FE teacher training standards, are inadequate and misdirected

    Is copyright blind to the visual?

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    This article argues that, with respect to the copyright protection of works of visual art, the general uneasiness that has always pervaded the relationship between copyright law and concepts of creativity produces three anomalous results. One of these is that copyright lacks much in the way of a central concept of 'visual art' and, to the extent that it embraces any concept of the 'visual', it is rooted in the rhetorical discourse of the Renaissance. This means that copyright is poorly equipped to deal with modern developments in the visual arts. Secondly, the pervasive effect of rhetorical discourse appears to have made it particularly difficult for copyright law to strike a meaningful balance between protecting creativity and permitting its use in further creative works. Thirdly, just when rhetorical discourse might have been useful in identifying the significance and materiality of the unique one-off work of visual art, copyright law chooses to ignore its implications

    Leveraging the Road to Health booklet as a unique patient identifier to monitor the prevention of mothertochild transmission programme

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    Background. Currently there is no unique patient identification system in the South African public health sector. Therefore, routine laboratory data cannot effectively be de-duplicated, thereby hampering surveillance of laboratory-diagnosed diseases such as mother-to-child transmission of HIV.Objectives. To determine the uptake of Road to Health booklet (RTHB) identifiers at HIV polymerase chain reaction (PCR) birth test and describe their performance in linking follow-up test results in the early infant diagnosis programme.Methods. Between May 2016 and May 2017, Tshwane District Clinical Services implemented a unique patient identifier pilot project in which a sticker-page of unique, readable, barcoded patient identifiers was incorporated in the patient-retained immunisation record (the RTHB) before distribution. Uptake of RTHB identifiers at birth was calculated as the proportion of HIV PCR tests in infants aged <6 days registered with an RTHB identifier over the total number of registered HIV PCR tests. Descriptive analysis of demographic details was performed among infants with two registered HIV PCR tests linked by the RTHB identifier, and performance of the National Health Laboratory Service Corporate Data Warehouse (NHLS CDW)-linking algorithm in matching RTHB-linked results was calculated using a 2 × 2 table.Results. A total of 5 309 HIV PCR birth tests registered with an RTHB identifier were extracted from the NHLS CDW over the 13-month period of the pilot project. The number of registered RTHB identifiers increased from 24 (2% of birth PCR tests) in May 2016, peaking at 728 (56% of birth PCR tests) in May 2017. Among infants with a registered RTHB identifier at birth, 635 (12%) had a subsequent linked HIV PCR test, as indicated by the same RTHB number registered for a later specimen. Demographic details at the time of birth and subsequent PCR test were compared, demonstrating that <4% of infants had exact matches for name, surname, date of birth and sex; 74% of birth tests had variations such as ‘born to’ or ‘baby of ’ in place of a first name; surnames matched exactly in 61% of cases; 18% (n=116) of infants had both tests performed at the same facility, of which only 27% (n=31) had the same patient folder number on both test results.Conclusions. Leveraging RTHBs as unique patient identifiers, even if used temporarily until linkage to other future national unique identifiers, promises to be an effective scalable approach to laboratory-based surveillance, facilitating healthcare provider access to all test results from birth

    The impact of health programmes to prevent vertical transmission of HIV. Advances, emerging health challenges and research priorities for children exposed to or living with HIV: Perspectives from South Africa

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    Over the past three decades, tremendous global progress in preventing and treating paediatric HIV infection has been achieved. This paper highlights the emerging health challenges of HIV-exposed uninfected (HEU) children and the ageing population of children living with HIV (CLHIV), summarises programmatic opportunities for care, and highlights currently conducted research and remaining research priorities in high HIV-prevalence settings such as South Africa. Emerging health challenges amongst HEU children and CLHIV include preterm delivery, suboptimal growth, neurodevelopmental delay, mental health challenges, infectious disease morbidity and mortality, and acute and chronic respiratory illnesses including tuberculosis, pneumonia, bronchiectasis and lymphocytic interstitial pneumonitis. CLHIV and HEU children require three different categories of care: (i) optimal routine child health services applicable to all children; (ii) routine care currently provided to all HEU children and CLHIV, such as HIV testing or viral load monitoring, respectively, and (iii) additional care for CLHIV and HEU children who may have growth, neurodevelopmental, behavioural, cognitive or other deficits such as chronic lung disease, and require varying degrees of specialised care. However, the translation thereof into practice has been hampered by various systemic challenges, including shortages of trained healthcare staff, suboptimal use of the patient-held child’s Road to Health book for screening and referral purposes, inadequate numbers and distribution of therapeutic staff, and shortages of assistive/diagnostic devices, where required. Additionally, in low-middle-income high HIV-prevalence settings, there is a lack of evidence-based solutions/models of care to optimise health amongst HEU and CLHIV. Current research priorities include understanding the mechanisms of preterm birth in women living with HIV to optimise preventive interventions; establishing pregnancy pharmacovigilance systems to understand the short-, medium- and long-term impact of in utero ART and HIV exposure; understanding the role of preconception maternal ART on HEU child infectious morbidity and long-term growth and neurodevelopmental trajectories in HEU children and CLHIV, understanding mental health outcomes and support required in HEU children and CLHIV through childhood and adolescence; monitoring HEU child morbidity and mortality compared with HIV-unexposed children; monitoring outcomes of CLHIV who initiated ART very early in life, sometimes with suboptimal ART regimens owing to medication formulation and registration issues; and testing sustainable models of care for HEU children and CLHIV including later reproductive care and support

    Decadal changes of the Western Arabian sea ecosystem

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    Historical data from oceanographic expeditions and remotely sensed data on outgoing longwave radiation, temperature, wind speed and ocean color in the western Arabian Sea (1950–2010) were used to investigate decadal trends in the physical and biochemical properties of the upper 300 m. 72 % of the 29,043 vertical profiles retrieved originated from USA and UK expeditions. Increasing outgoing longwave radiation, surface air temperatures and sea surface temperature were identified on decadal timescales. These were well correlated with decreasing wind speeds associated with a reduced Siberian High atmospheric anomaly. Shoaling of the oxycline and nitracline was observed as well as acidification of the upper 300 m. These physical and chemical changes were accompanied by declining chlorophyll-a concentrations, vertical macrofaunal habitat compression, declining sardine landings and an increase of fish kill incidents along the Omani coast

    Optical absorption and single-particle excitations in the 2D Holstein t-J model

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    To discuss the interplay of electronic and lattice degrees of freedom in systems with strong Coulomb correlations we have performed an extensive numerical study of the two-dimensional Holstein t-J model. The model describes the interaction of holes, doped in a quantum antiferromagnet, with a dispersionsless optical phonon mode. We apply finite-lattice Lanczos diagonalization, combined with a well-controlled phonon Hilbert space truncation, to the Hamiltonian. The focus is on the dynamical properties. In particular we have evaluated the single-particle spectral function and the optical conductivity for characteristic hole-phonon couplings, spin exchange interactions and phonon frequencies. The results are used to analyze the formation of hole polarons in great detail. Links with experiments on layered perovskites are made. Supplementary we compare the Chebyshev recursion and maximum entropy algorithms, used for calculating spectral functions, with standard Lanczos methods.Comment: 32 pages, 12 figures, submitted to Phys. Rev.

    A neglected pool of labour? Frontline service work and hotel recruitment in Glasgow

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    The paper presented considers soft skills in the hospitality sector and explores how managers in four hotels in Glasgow, Scotland enact recruitment and selection processes. Empirically, the analysis is based on a rich cross case comparison including interviews, observations, attendance at training events and analysis of hotels’ recruitment and selection policies. Conceptually, the analysis draws on the work of Pierre Bourdieu and Andrew Sayer, portraying an understanding of social class as a social, economic, and cultural category and people’s agency as shaped by their habitus and lay normativity. Crucially, the paper reveals the pivotal role individual managers play in enabling and constraining opportunities for employment in the enactment of hotel recruitment policy and engagement with job applicants and new recruits. Overall, the analysis suggests that, despite many deterministic analyses of class, an organization’s recruitment, learning and development strategies, plus management’s commitment to make a difference, can positively impact on those who might otherwise be part of a neglected pool of labour
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