Nonlinear elastic analysis of concrete beams based on the Smeared Crack Approach

In the present study, an analysis of plain and reinforced concrete beams under monotonic loading was made based on the Fixed Smeared Crack approach. The objectives of this research were to analyze the nonlinear behavior of the selected cases of analysis and to propose an alternative and simple model for the analysis of beams under service loadings, by means of Committee 435 of the American Concrete Institute. A brittle model for concrete and a linear-elastic behavior for steel reinforcement bars were considered. Results are presented through force-displacement curves and the sequence of cracking propagation. Also, a comparison of calculated instantaneous deflections of simply supported beams was made between the proposed model and other researches. It was verified that the proposed algorithm can predict adequately the cracking process and the deflections of beams subjected to service loadings, taking into account experimental results from other authors

Evaluaci?n de la actividad bactericida de fracciones enriquecidas en flavonoides a partir de: psidium guajava l. (guayaba), calendula officinalis l. (cal?ndula), l. (romero) y matricaria chamomilla l. (manzanilla) sobre: erwinia carotovora (dye).

88 P?ginasLas plantas alimenticias son infectadas por bacterias originando graves problemas fitosanitarios que generan p?rdidas econ?micas a los agricultores. Estos microorganismos desarrollan resistencia hacia los antibi?ticos debido a su uso inadecuado. Una alternativa en el control de bacterias fitopat?genas es el empleo de extractos bot?nicos, con lo cual se busca reducir el impacto econ?mico y ambiental en el sector agr?cola. Empleando diversos ?rganos de Psidium guajava L. (guayaba), Calendula officinalis L. (cal?ndula), Rosmarinus officinalis L. (romero) y Matricaria chamomilla L. (manzanilla) se elaboraron extractos etan?licos, de los cuales se obtuvieron cuatro (4) fracciones mediante una serie eluotr?pica de solventes (?ter de petr?leo, acetato de etilo, n-butanol y agua). Los extractos y sus fracciones fueron caracterizados fitoqu?micamente con cromatograf?as en capa delgada para detectar flavonoides (fracci?n et?rea descartada) y su actividad in vitro se evalu? frente a la cepa E. carotovora mediante el m?todo de inhibici?n zonal (m?todo de difusi?n en agar), utilizando concentraciones de 5.000, 7.000 y 10.000 (?g/mL), con mediciones de halos de inhibici?n a las 24 y 48 horas. Los resultados obtenidos mediante estas pruebas determinaron un control positivo de las plantas P. guajava con su extracto etan?lico y sus 3 fracciones y C. officinalis en su fracci?n acetato de etilo. Los resultados obtenidos a partir del estudio de actividad biol?gica in vitro sugieren que las fracciones n-butanol y acuosa en la especia P. guajava y la fracci?n acetato de etilo en la especia C. officinalis son promisorias para futuros ensayos de actividad bactericida y otros estudios qu?micos.ABSTRACT Food plants are infected by causing serious phytosanitary problems caused economic losses to farmers bacteria. These microorganisms develop resistance to antibiotics due to improper use. An alternative in the control of plant pathogenic bacteria is the use of botanical extracts, which seeks to reduce the economic and environmental impact on the agricultural sector. Using various organs of Psidium guajava L. ( guava), Calendula officinalis L. (marigold), Rosmarinus officinalis L. (rosemary ) and Matricaria chamomilla L. (chamomile ) ethanol extracts were prepared , of which four (4) fractions were obtained by eluotropic series of solvents (petroleum ether, ethyl acetate, n-butanol and water). The extracts and fractions were characterized phytochemically with thin layer chromatography for any flavonoids (ethereal fraction discarded) and its in vitro activity was evaluated against strain E. carotovora by the method of zonal inhibition (diffusion method on agar) using concentrations of 5.000, 7.000 and 10.000 (?g/mL), with measurements of zones of inhibition at 24 and 48 hours. The results obtained by these tests determined a positive control of plants with P. guajava ethanol extract and its fractions and its 3 in the C. officinalis ethyl acetate fraction. The results obtained from the study of biological activity in vitro suggest that n - butanol fraction and water at P. guajava spice and ethyl acetate fraction in the spice C. officinalis are promising for future trials and other studies bactericidal activity chemicals.INTRODUCCI?N 16 1. MARCO TE?RICO 18 1.1 IMPORTANCIA DE LAS ENFERMEDADES FITOPAT?GENAS 18 1.2 FITOENFERMEDADES POR BACTERIAS 19 1.3 CONTROL DE BACTERIAS FITOPAT?GENAS 22 1.3.1 Uso de Antibi?ticos 22 1.4 EXTRACTOS VEGETALES Y SU PAPEL EN LA AGRICULTURA 23 1.4.1 Uso Mundial, Regional y Local. 23 1.4.2 Uso en el campo. 23 1.5 DESCRIPCI?N DE E. carotovora. 27 1.5.1 Generalidades. 27 1.5.2 Situaci?n actual 28 1.5.3 Identificaci?n taxon?mica seg?n la N.C.B.I. 28 1.5.4 Tratamiento 29 1.5.5 Incidencia. 29 1.6 DESCRIPCI?N BOT?NICA DE LAS ESPECIES VEGETALES 30 1.6.1 Descripci?n bot?nica P. guajava 30 1.6.1.1 Flavonoides reportados y actividad biol?gica 31 1.6.2 Descripci?n bot?nica R. officinalis 32 5 1.6.2.1 Flavonoides reportados y actividad biol?gica 32 1.6.3 Descripci?n bot?nica C. officinalis 33 1.6.3.1 Flavonoides reportados y actividad biol?gica 34 1.6.4 Descripci?n bot?nica M. Chamomilla 35 1.6.4.1 Flavonoides reportados y actividad biol?gica 36 1.7 FLAVONOIDES 36 2. PARTE EXPERIMENTAL 39 2.1 EQUIPOS REACTIVOS Y MATERIALES 39 2.1.1 Equipos 39 2.1.2 Reactivos 39 2.1.3 Materiales 40 2.2 MATERIAL VEGETAL 41 2.2.1 Material microbiol?gico 41 2.3 METODOLOGIA - ENSAYOS FITOQUIMICOS 41 2.3.1 Elaboraci?n de los extractos etan?licos de P. guajava, C. officinalis, R. officinalis y M. chamomilla 41 2.3.2 Fraccionamiento del extracto etan?lico 43 2.3.3 Detecci?n de flavonoides en extractos etan?licos y fracciones primarias de P. guajava, C. officinalis, R. officinalis y M. chamomilla 44 2.4 METODOLOG?A BIOL?GICA 45 2.4.1 Bioensayo de la actividad bactericida de los extractos y fracciones sobre E. carotovora 45 6 2.4.2 Determinaci?n de la concentraci?n inhibitoria para el control positivo (Cefalexina) 46 2.4.3 Disoluci?n de los extractos etan?licos y fracciones primarias 47 2.5 AN?LISIS ESTAD?STICO 48 2.5.1 M?todo estad?stico 48 3. RESULTADOS Y DISCUSI?N 49 3.1 EXTRACCI?N Y FRACCIONAMIENTO DE LOS EXTRACTOS ETAN?LICOS 49 3.2 ESTUDIO FITOQU?MICO POR CCD DE LOS EXTRACTOS Y FRACCIONES 52 3.2.1 An?lisis de los extractos 52 3.2.2 An?lisis de las fracciones 54 3.3 PRUEBAS DE ACTIVIDAD BIOL?GICA IN VITRO DE LOS EXTRACTOS ETAN?LICOS Y FRACCIONES OBTENIDAS DE P. GUAJAVA, R. OFFICINALIS, C. OFFICINALIS Y M.CHAMOMILLA SOBRE E. CAROTOVORA 59 3.4 RESULTADOS AN?LISIS ESTAD?STICO 66 4. CONCLUSIONES Y RECOMENDACIONES 78 4.1 CONCLUSIONES 78 4.2 RECOMENDACIONES 79 5. REFERENCIAS 8

The Digital Library of the Caribbean (dLOC): Creating a Shared Research Foundation

This article explains the history and development of the Digital Library of the Caribbean (dLOC) as a research foundation for reading, writing, and researching the Caribbean and thus as part of the scholarly cyberinfrastructure for Caribbean Studies. As a research foundation, dLOC includes technical, social, governmental, and procedural supports including open source tools, executive and scholarly advisory boards for governance, permissions-based rights model to support intellectual property as well as cultural and moral rights, and a core support team. As a research foundation, dLOC supports new forms of research as well as new ways of reading and writing Caribbean Studies

Holocene Fire Occurrence and Alluvial Responses at the Leading Edge of Pinyon–Juniper Migration in the Northern Great Basin, USA

Fire and vegetation records at the City of Rocks National Reserve (CIRO), south-central Idaho, display the interaction of changing climate, fire and vegetation along the migrating front of single-leaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma). Radiocarbon dating of alluvial charcoal reconstructed local fire occurrence and geomorphic response, and fossil woodrat (Neotoma) middens revealed pinyon and juniper arrivals. Fire peaks occurred ~10,700–9500, 7200–6700, 2400–2000, 850–700, and 550–400 cal yr BP, whereas ~9500–7200, 6700–4700 and ~1500–1000 cal yr BP are fire-free. Wetter climates and denser vegetation fueled episodic fires and debris flows during the early and late Holocene, whereas drier climates and reduced vegetation caused frequent sheetflooding during the mid-Holocene. Increased fires during the wetter and more variable late Holocene suggest variable climate and adequate fuels augment fires at CIRO. Utah juniper and single-leaf pinyon colonized CIRO by 3800 and 2800 cal yr BP, respectively, though pinyon did not expand broadly until ~700 cal yr BP. Increased fire-related deposition coincided with regional droughts and pinyon infilling ~850–700 and 550–400 cal yr BP. Early and late Holocene vegetation change probably played a major role in accelerated fire activity, which may be sustained into the future due to pinyon–juniper densification and cheatgrass invasion

Application of large area SiPMs for the readout of a plastic scintillator based timing detector

In this study an array of eight 6 mm x 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm x 6 cm x 1 cm and 120 cm x 11 cm x 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results

Application of large area SiPMs for the readout of a plastic scintillator based timing detector

In this study an array of eight 6 mm x 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm x 6 cm x 1 cm and 120 cm x 11 cm x 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results

CRANKITE: a fast polypeptide backbone conformation sampler

Background: CRANKITE is a suite of programs for simulating backbone conformations of polypeptides and proteins. The core of the suite is an efficient Metropolis Monte Carlo sampler of backbone conformations in continuous three-dimensional space in atomic details. Methods: In contrast to other programs relying on local Metropolis moves in the space of dihedral angles, our sampler utilizes local crankshaft rotations of rigid peptide bonds in Cartesian space. Results: The sampler allows fast simulation and analysis of secondary structure formation and conformational changes for proteins of average length

Decelerated sub-relativistic material with energy Injection

We investigate the evolution of the afterglow produced by the deceleration of the non-relativistic material due to its surroundings. The ejecta mass is launched into the circumstellar medium with equivalent kinetic energy expressed as a power-law velocity distribution $E\propto (\Gamma\beta)^{-\alpha}$. The density profile of this medium follows a power law $n(r)\propto r^{-k}$ with $k$ the stratification parameter, which accounts for the usual cases of a constant medium ($k=0$) and a wind-like medium ($k=2$). A long-lasting central engine, which injects energy into the ejected material as ($E\propto t^{1-q}$) was also assumed. With our model, we show the predicted light curves associated with this emission for different sets of initial conditions and notice the effect of the variation of these parameters on the frequencies, timescales and intensities. The results are discussed in the Kilonova scenario.Comment: Presented at the 37th International Cosmic Ray Conference (ICRC2021), Berlin, German

A theoretical model of an off-axis GRB jet

In light of the most recent observations of late afterglows produced by the merger of compact objects or by the core-collapse of massive dying stars, we research the evolution of the afterglow produced by an off-axis top-hat jet and its interaction with a surrounding medium. The medium is parametrized by a power law distribution of the form $n(r)\propto r^{-k}$ is the stratification parameter and contains the development when the surrounding density is constant ($k=0$) or wind-like ($k=2$). We develop an analytical synchrotron forward-shock model when the outflow is viewed off-axis, and it is decelerated by a stratified medium. Using the X-ray data points collected by a large campaign of orbiting satellites and ground telescopes, we have managed to apply our model and fit the X-ray spectrum of the GRB afterglow associated to SN 2020bvc with conventional parameters. Our model predicts that its circumburst medium is parametrized by a power law with stratification parameter $k=1.5$.Comment: Presented at the 37th International Cosmic Ray Conference (ICRC2021), Berlin, German