152 research outputs found

    Comparison of some Reduced Representation Approximations

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    In the field of numerical approximation, specialists considering highly complex problems have recently proposed various ways to simplify their underlying problems. In this field, depending on the problem they were tackling and the community that are at work, different approaches have been developed with some success and have even gained some maturity, the applications can now be applied to information analysis or for numerical simulation of PDE's. At this point, a crossed analysis and effort for understanding the similarities and the differences between these approaches that found their starting points in different backgrounds is of interest. It is the purpose of this paper to contribute to this effort by comparing some constructive reduced representations of complex functions. We present here in full details the Adaptive Cross Approximation (ACA) and the Empirical Interpolation Method (EIM) together with other approaches that enter in the same category

    Conservation of co-evolved interactions: understanding the Maculinea–Myrmica complex

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    1. The six papers in this Special Issue of Insect Conservation and Diversity are presented as a gedenkschrift honouring ground‐breaking contributions made by the late Graham Elmes towards understanding the biology of Myrmica ants and their social parasites. 2. A common theme is that each research paper contributes new knowledge applicable to the future survival of Maculinea (= Phengaris) species of butterflies, which have become flagships for insect conservation across Europe. All Maculinea species are highly specialised, with larvae that feed briefly on a specific foodplant before living underground for 11–23 months as social parasites of Myrmica colonies. 3. This introductory overview provides a brief history of the research that has led to the current collection, with emphasis on Graham Elmes' life and work. It is followed by three research papers that illustrate the diversity, socio‐biology and ecology of Myrmica ants. A fourth describes an extreme adaptation that increases the efficiency with which some populations of Maculinea larvae exploit the resources within Myrmica nests. A fifth, more theoretical, paper models the constraints that typically lead to host specificity among social parasites and explores why host switches are rare and quick

    Ação de fitoreguladores nos teores de macronutrientes em tomateiro (Lycopersicon esculentum Mill.)

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    This research deals with the effects of exogenous growth regulators on mineral nutrition of the tomato plant (Lycopersicon esculentum Mill, cv. 'Miguel Pereira'). To study the influence on mineral nutrition, (2-chloroethyl) trimethilammonium chloride (CCC), at concentration of 2,000 ppm, succinic acid-2,2-dimethylhydrazide (SADH) (4,000 ppm), gibberellic acid (GA) (100 ppm), (2-chloroethyl) phosphonic acid (CEPA) (200 ppm), indole-3-acetic acid (IAA) (100 ppm), and 6-furfurylamino purine (FAP) (500 ppm) were applied. Higher levels of nitrogen, calcium and magnesium occurred in the stem of plants sprayed with CCC. Treatments with FAP. SADH and CEPA demonstrated an increase in nitrogen levels in the stem. CEPA also increased calcium contents in stems. Growth regulators used did not alter the levels of macronutrients in leaves of tomatoes in relation to check plants.Verificaram-se os efeitos da aplicação de reguladores vegetais na nutrição mineral do tomateiro. Para isto aplicaram-se, em plantas com 4 folhas, cloreto de (2-cloroetil) trimetilamĂŽnio (CCC) 2.000 ppm, ĂĄcido succĂ­nico-2,2-dimetilhidrazida (SADH) 4.000 ppm, ĂĄcido giberĂ©lico (GA) 100 ppm, ĂĄcido (2-cloroetil) fosfĂŽnico (CEPA) 200 ppm, ĂĄcido 3-indolacĂ©tico (IAA) 100 ppm e 6-furfurilaminopurina (FAP) na concentração de 500 ppm. NĂ­veis mais elevados de nitrogĂȘnio, cĂĄlcio e magnĂ©sio foram determinados nas hastes de plantas pulverizadas com CCC. Tratamento com CEPA promoveu aumento nos teores de nitrogĂȘnio e cĂĄlcio nas hastes de tomateiro. NĂ­veis mais elevados de nitrogĂȘnio foram determinados nas hastes de plantas tratadas com SADH e FAP. Os reguladores de crescimento utilizados nĂŁo afetaram os nĂ­veis de macronutrientes nas folhas do tomateiro com relação Ă s controle

    An Examination of Chimpanzee Use in Human Cancer Research

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    Advocates of chimpanzee research claim the genetic similarity of humans and chimpanzees make them an indispensable research tool to combat human diseases. Given that cancer is a leading cause of human death worldwide, one might expect that if chimpanzees were needed for, or were productive in, cancer research, then they would have been widely used. This comprehensive literature analysis reveals that chimpanzees have scarcely been used in any form of cancer research, and that chimpanzee tumours are extremely rare and biologically different from human cancers. Often, chimpanzee citations described peripheral use of chimpanzee cells and genetic material in predominantly human genomic studies. Papers describing potential new cancer therapies noted significant concerns regarding the chimpanzee model. Other studies described interventions that have not been pursued clinically. Finally, available evidence indicates that chimpanzees are not essential in the development of therapeutic monoclonal antibodies. It would therefore be unscientific to claim that chimpanzees are vital to cancer research. On the contrary, it is reasonable to conclude that cancer research would not suffer, if the use of chimpanzees for this purpose were prohibited in the US. Genetic differences between humans and chimpanzees, make them an unsuitable model for cancer, as well as other human diseases

    A "critical" climatic evaluation of last interglacial (MIS 5e) records from the Norwegian Sea

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    Sediment cores from the Norwegian Sea were studied to evaluate interglacial climate conditions of the marine isotope stage 5e (MIS 5e). Using planktic forminiferal assemblages as the core method, a detailed picture of the evolution of surface water conditions was derived. According to our age model, a step-like deglaciation of the Saalian ice sheets is noted between ca. 135 and 124.5 Kya, but the deglaciation shows little response with regard to surface ocean warming. From then on, the rapidly increasing abundance of subpolar forminifers, concomitant with decreasing iceberg indicators, provides evidence for the development of interglacial conditions sensu stricto (5e-ss), a period that lasted for about 9 Ky. As interpreted from the foraminiferal records, and supported by the other proxies, this interval of 5e-ss was in two parts: showing an early warm phase, but with a fresher, i.e., lower salinity, water mass, and a subsequent cooling phase that lasted until ca. 118.5 Kya. After this time, the climatic optimum with the most intense advection of Atlantic surface water masses occurred until ca. 116 Kya. A rapid transition with two notable climatic perturbations is observed subsequently during the glacial inception. Overall, the peak warmth of the last interglacial period occurred relatively late after deglaciation, and at no time did it reach the high warmth level of the early Holocene. This finding must be considered when using the last interglacial situation as an analogue model for enhanced meridional transfer of ocean heat to the Arctic, with the prospect of a future warmer climate

    Mineral nutrition of vegetable crops: XXV - Mineral nutrition of new zealand spinach plant (Tetragonia expansa Murr.)

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    The present work was carried out in order to study: a - the effect of omission and presence of the macronutrients and boron on the growth of the plants; b - deficiency symptoms of macronutrients, as well of boron; c - the effect of the deficiency of each nutrient on the chemical composition of the plants. Young spinach plants were grown in pots containing pure quartz sand. Several times a day the plants were irrigated by percolation with nutrient solutions. The treatments were: complete solution and deficient solution, in which each one of the macronutrients was omitted as well boron. Soon as the malnutrition symptoms appered, the plants were harvested and analysed chemically. - symptoms of malnutrition are easily observed for N, K, Ca and B. - symptoms of malnutrition for P, S and Mg are not easily identified. - the nutrient content, in dry matter, in deficient leaves and healthy leaves is:O trabalho teve como objetivo estudar alguns aspectos da nutrição mineral do espinafre (Tetragonia expansa Murr.) no que concerne: 1 - Efeitos da omissĂŁo dos macronutrientes e do boro, na obtenção de um quadro sintomatolĂłgico; 2 - Efeitos das carĂȘncias na produção de matĂ©ria seca e composição quĂ­mica da planta. Mudas com trinta dias de idade foram transplantadas para soluçÔes nutritivas carentes nos macronutrientes e/ou em boro. A coleta das plantas foi realizada quando os sintomas de deficiĂȘncia se tornaram evidentes. No material seco procedeu-se a anĂĄlise quĂ­mica. Os dados mostram que: 1 - os sintomas visuais de deficiĂȘncia de N, K, Ca e B apresentam-se bem definidos; sendo que os de P, Mg e S sĂŁo de difĂ­cil caracterização ; 2 - os teores dos nutrientes em plantas sadias e deficientes sĂŁo

    Open data from the third observing run of LIGO, Virgo, KAGRA, and GEO

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    The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

    Constraints on the cosmic expansion history from GWTC–3

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    We use 47 gravitational wave sources from the Third LIGO–Virgo–Kamioka Gravitational Wave Detector Gravitational Wave Transient Catalog (GWTC–3) to estimate the Hubble parameter H(z), including its current value, the Hubble constant H0. Each gravitational wave (GW) signal provides the luminosity distance to the source, and we estimate the corresponding redshift using two methods: the redshifted masses and a galaxy catalog. Using the binary black hole (BBH) redshifted masses, we simultaneously infer the source mass distribution and H(z). The source mass distribution displays a peak around 34 M⊙, followed by a drop-off. Assuming this mass scale does not evolve with the redshift results in a H(z) measurement, yielding H0=68−8+12 km   s−1 Mpc−1{H}_{0}={68}_{-8}^{+12}\,\mathrm{km}\ \,\ {{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1} (68% credible interval) when combined with the H0 measurement from GW170817 and its electromagnetic counterpart. This represents an improvement of 17% with respect to the H0 estimate from GWTC–1. The second method associates each GW event with its probable host galaxy in the catalog GLADE+, statistically marginalizing over the redshifts of each event's potential hosts. Assuming a fixed BBH population, we estimate a value of H0=68−6+8 km   s−1 Mpc−1{H}_{0}={68}_{-6}^{+8}\,\mathrm{km}\ \,\ {{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1} with the galaxy catalog method, an improvement of 42% with respect to our GWTC–1 result and 20% with respect to recent H0 studies using GWTC–2 events. However, we show that this result is strongly impacted by assumptions about the BBH source mass distribution; the only event which is not strongly impacted by such assumptions (and is thus informative about H0) is the well-localized event GW190814

    Factors Associated with School Lunch Consumption: Reverse Recess and School “Brunch”

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    Background: While school foods have become healthier under the Healthy, Hunger Free Kids Act, research suggests there is still substantial food waste in cafeterias. It is therefore necessary to study factors that can impact food consumption, including holding recess before lunch (“reverse recess”) and starting lunch periods very early or very late. Objective: This study examined the association between the timing of recess (pre-lunch vs post-lunch recess), the timing of the lunch period, and food consumed by students at lunch. Design: We conducted a secondary data analysis from a repeated cross-sectional design. Participants/setting: An 8-week plate waste study examining 20,183 trays of food was conducted in New Orleans, LA, in 2014. The study involved 1,036 fourth- and ïŹfth-grade students from eight public schools. Main outcome measures We measured percent of entrĂ©es, fruit, vegetables, and milk consumed by students at lunch. Statistical analyses performed We used mixed-model analyses, controlling for student sex, grade, and the timing of the lunch period, and examined the association between reverse recess and student lunch consumption. Mixed-model analyses controlling for student sex, grade, and recess status examined whether the timing of the lunch period was associated with student lunch consumption. Results: On average, students with reverse recess consumed 5.1% more of their fruit than students with post-lunch recess (PÂŒ0.009), but there were no signiïŹcant differences in entrĂ©es, vegetables, or milk intake. Compared to students with “midday” lunch periods, on average students with “early” lunch periods consumed 5.8% less of their entrĂ©es (P\u3c0.001) and 4.5% less of their milk (PÂŒ0.047). Students with “late” lunch periods consumed 13.8% less of their entrĂ©es (P\u3c0.001) and 15.9% less of their fruit (P\u3c0.001). Conclusions: Reverse recess was associated with increased fruit consumption. “Early” lunch periods were associated with decreased entrĂ©e and milk consumption, and “late” lunch periods were associated with decreased entrĂ©e and fruit consumption. Additional research is recommended to determine whether these associations are causal
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