137 research outputs found

    Reduction-Based Creative Telescoping for Algebraic Functions

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    Continuing a series of articles in the past few years on creative telescoping using reductions, we develop a new algorithm to construct minimal telescopers for algebraic functions. This algorithm is based on Trager's Hermite reduction and on polynomial reduction, which was originally designed for hyperexponential functions and extended to the algebraic case in this paper

    Minimising the risks of tailings dams with remote sensing data

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    Tailings dams are used to store toxic mine waste and effluent. Their failure rate is estimated to be more than two orders of magnitude greater than that of conventional water retention dams, causing loss of lives, irreversible damages to ecosystems and large economic damages. There is a need for a cost effective service to monitor operational, closed and abandoned tailings dams, especially those in remote locations, to help forecast potentially catastrophic failures

    DAMSAT: An Eye in the Sky for Monitoring Tailings Dams

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    During the past decade, there have been a number of catastrophic tailings dam failures. Affordable monitoring systems, as well as methods to assess the risk posed to communities living downstream of these structures, are needed. In recent years the availability and accuracy of remote sensing information has increased, whilst its cost has decreased. This paper provides an overview of DAMSAT, a web-based system that brings together Earth observation and other data to help governments and mining companies monitor tailing dams, and estimate the downstream risks they pose. The methods developed are being piloted in Peru at a number of tailings dams, with the overall goal of improving the decision making process and sharing of information with respect to managing these structures. Engagement with Peruvian stakeholders has shown that DAMSAT provides tools that can help government authorities both reduce the risks and increase the sustainability of mining

    The potential to reduce the risks posed by tailings dams using satellite-based information

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    The failures of tailings dams, used to store waste from mining operations, pose a significant risk to the health of people and the environment, especially in many low income countries where the extractive industry makes a significant contribution to the nation's wealth. Recently the rate of failure of tailings dams has increased. The demand for raw materials and increases in intense rainfall as a result of climate change will exacerbate this issue in the future. The monitoring of tailings dams is essential to reduce their probability of failure. Virtually all the recent tailings dams failures were preventable. However, there is generally a lack of transparency and accountability for these structures by mining companies. In the past 10 years an increase in the global coverage and accuracy of Earth Observation (EO) based information has made it technically possible to use EO-based data to remotely monitor critical aspects of tailings dams, such as their deformation and the leakage of pollutants. This paper describes the development of an EO-based service, being piloted in Peru, which would allow tailings dams to be monitored cost effectively, and also help to forecast any potentially risk inducing behaviour from tailings dams several weeks in advance. Many regulatory bodies in low income countries do not have the resources to adequately monitor mining operations. A low cost EO-based system could improve the transparency and safety of tailings dams, allowing timely preventative interventions to be made where the probability of failure is found to be high

    Watermelon configurations with wall interaction: exact and asymptotic results

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    We perform an exact and asymptotic analysis of the model of nn vicious walkers interacting with a wall via contact potentials, a model introduced by Brak, Essam and Owczarek. More specifically, we study the partition function of watermelon configurations which start on the wall, but may end at arbitrary height, and their mean number of contacts with the wall. We improve and extend the earlier (partially non-rigorous) results by Brak, Essam and Owczarek, providing new exact results, and more precise and more general asymptotic results, in particular full asymptotic expansions for the partition function and the mean number of contacts. Furthermore, we relate this circle of problems to earlier results in the combinatorial and statistical literature.Comment: AmS-TeX, 41 page

    Multiple (inverse) binomial sums of arbitrary weight and depth and the all-order epsilon-expansion of generalized hypergeometric functions with one half-integer value of parameter

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    We continue the study of the construction of analytical coefficients of the epsilon-expansion of hypergeometric functions and their connection with Feynman diagrams. In this paper, we show the following results: Theorem A: The multiple (inverse) binomial sums of arbitrary weight and depth (see Eq. (1.1)) are expressible in terms of Remiddi-Vermaseren functions. Theorem B: The epsilon expansion of a hypergeometric function with one half-integer value of parameter (see Eq. (1.2)) is expressible in terms of the harmonic polylogarithms of Remiddi and Vermaseren with coefficients that are ratios of polynomials. Some extra materials are available via the www at this http://theor.jinr.ru/~kalmykov/hypergeom/hyper.htmlComment: 24 pages, latex with amsmath and JHEP3.cls; v2: some typos corrected and a few references added; v3: few references added

    LC–DAD–MS phenolic characterisation of six invasive plant species in Croatia and determination of their antimicrobial and cytotoxic activity

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    Invasive plants’ phytochemicals are important for their invasiveness, enabling them to spread in new environments. However, these chemicals could offer many pharmaceutical compounds or active ingredients for herbal preparations. This study provides the first LC–MS phytochemical screening of six invasive alien plant species (IAPS) in the Istria region (Croatia): Ailanthus altissima, Ambrosia artemisiifolia, Conyza canadensis, Dittrichia viscosa, Erigeron annuus, and Xanthium strumarium. The study aims to identify and quantify the phenolic content of their leaf extracts and assess their antimicrobial and cytotoxic potential. A total of 32 species-specific compounds were recorded. Neochlorogenic, chlorogenic, and 5-p-coumaroylquinic acids, quercetin-3-glucoside, and kaempferol hexoside were detected in all the tested IAPS. Hydroxycinnamic acid derivatives were the main components in all the tested IAPS, except in E. annuus, where flavanones dominated with a share of 70%. X. strumarium extract had the best activity against the tested bacteria, with an average MIC value of 0.11 mg/mL, while A. altissima and X. strumarium extracts had the best activity against the tested fungi, with an average MIC value of 0.21 mg/mL in both cases. All the plant extracts studied, except X. strumarium, were less cytotoxic than the positive control. The results provided additional information on the phytochemical properties of IAPS and their potential for use as antimicrobial agents.SUPPLEMENTARY MATERIALS : Figure S1: Heat map presenting the representations of phenolic groups in different invasive plants; Figure S2: Chromatogram of the acetone extracts of the plant species leaves developed in ethyl acetate/methanol/water (EMW) solvent system sprayed with vanillin– sulphuric acid and TLC bioautograms; Table S1: Spectrum, mass-to-charge ratio (m/z) values of the molecular masses, and main fragments (MS2—second-generation product ion, MS3—thirdgeneration product ion) in negative ion mode ((M-H)−) identified with ESI–MS and the distribution of individual compounds in different invasive plants.The Croatian Science Foundation, the Slovenian Research Agency (ARRS) and the University of Pretoria, South Africa.https://www.mdpi.com/journal/plantsdm2022Paraclinical Science

    Carbohydrate, phenolic and antioxidant level in relation to chlorophyll a content in oilseed winter rape (Brassica napus L.) inoculated with Leptosphaeria maculans

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    Syftet med föreliggande studien var att undersöka om sjuksköterskors egna rökvanor pĂ„verkar attityden till tobakspreventivt arbete pĂ„ sjukhuset, bĂ„de till tobakspreventivt arbete med patienterna och attityden till rökfritt sjukhus. Studien Ă€r empirisk och utfördes genom kvalitativa intervjuer med sex sjuksköterskor pĂ„ en vĂ„rdavdelning pĂ„ ett sjukhus i södra Sverige. Data frĂ„n intervjuerna analyserades och resulterade i sju olika teman: Preventiva rollen, Kunskap om prevention, Vem skall leda det preventiva arbetet, Rökkontroll, UtbildningsnivĂ„ och rökning, Sjuksköterskan, en förebild?, Vem ska hjĂ€lpa patienten vid rökstopp pĂ„ sjukhuset?, Är det nĂ„gon skillnad mellan icke rökande och rökande vad avser rökpreventionen?. Den preventiva rollen hamnade i fokus och skillnader fanns mellan rökande och icke rökande sjuksköterskor bĂ„de vad gĂ€ller preventivt omvĂ„rdnasarbete och kontrollThe aim of the present study is to investigate whether nurses smoking habits influence their attitude to tobacco prevention in hospitals, both in their work with patients and regarding their attitude to hospital smoking bans. The following question was posed: is there a difference between smoking and non-smoking nurses in patient-care activities regarding smoking prevention and control? The study is qualitative, based on qualitative interviews with six nurses at a ward of a hospital in Sweden. Interview data were analyzed and eight themes emerged: the role in prevention work knowledge of prevention who is to lead prevention work smoking control smoking and education levels the nurse as a role model who is to help the patient give up smoking possible differences between nonsmoking and smoking nurses regarding smoking prevention. The role in prevention work turned out to be central. Smoking nurses had greater difficulties in connection with preventive work and control, due to their personal experience of how hard it can be to give up smoking habits

    Elliptic integral evaluations of Bessel moments

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    We record what is known about the closed forms for various Bessel function moments arising in quantum field theory, condensed matter theory and other parts of mathematical physics. More generally, we develop formulae for integrals of products of six or fewer Bessel functions. In consequence, we are able to discover and prove closed forms for cn,k:=∫0∞tkK0n(t)dtc_{n,k}:=\int_0^\infty t^k K_0^n(t) {\rm d}t with integers n=1,2,3,4n=1,2,3,4 and k≄0k\ge0, obtaining new results for the even moments c3,2kc_{3,2k} and c4,2kc_{4,2k}. We also derive new closed forms for the odd moments sn,2k+1:=∫0∞t2k+1I0(t)K0n−1(t)dts_{n,2k+1}:=\int_0^\infty t^{2k+1}I_0^{}(t) K_0^{n-1}(t) {\rm d}t with n=3,4n=3,4 and for tn,2k+1:=∫0∞t2k+1I02(t)K0n−2(t)dtt_{n,2k+1}:=\int_0^\infty t^{2k+1}I_0^2(t) K_0^{n-2}(t) {\rm d}t with n=5n=5, relating the latter to Green functions on hexagonal, diamond and cubic lattices. We conjecture the values of s5,2k+1s_{5,2k+1}, make substantial progress on the evaluation of c5,2k+1c_{5,2k+1}, s6,2k+1s_{6,2k+1} and t6,2k+1t_{6,2k+1} and report more limited progress regarding c5,2kc_{5,2k}, c6,2k+1c_{6,2k+1} and c6,2kc_{6,2k}. In the process, we obtain 8 conjectural evaluations, each of which has been checked to 1200 decimal places. One of these lies deep in 4- dimensional quantum field theory and two are probably provable by delicate combinatorics. There remains a hard core of five conjectures whose proofs would be most instructive, to mathematicians and physicists alike.Comment: 51 pages, 1 Postscript figure, uses amsmath.sty, added reference
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