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Sample records for angiosperm radiation revisited

  1. Leaf evolution in Southern Hemisphere conifers tracks the angiosperm ecological radiation

    OpenAIRE

    Biffin, Ed; Brodribb, Timothy J.; Hill, Robert S.; Thomas, Philip; Lowe, Andrew J.

    2011-01-01

    The angiosperm radiation has been linked to sharp declines in gymnosperm diversity and the virtual elimination of conifers from the tropics. The conifer family Podocarpaceae stands as an exception with highest species diversity in wet equatorial forests. It has been hypothesized that efficient light harvesting by the highly flattened leaves of several podocarp genera facilitates persistence with canopy-forming angiosperms, and the angiosperm ecological radiation may have preferentially favour...

  2. Putting scales into evolutionary time: the divergence of major scale insect lineages (Hemiptera) predates the radiation of modern angiosperm hosts

    Science.gov (United States)

    Vea, Isabelle M.; Grimaldi, David A.

    2016-01-01

    The radiation of flowering plants in the mid-Cretaceous transformed landscapes and is widely believed to have fuelled the radiations of major groups of phytophagous insects. An excellent group to test this assertion is the scale insects (Coccomorpha: Hemiptera), with some 8,000 described Recent species and probably the most diverse fossil record of any phytophagous insect group preserved in amber. We used here a total-evidence approach (by tip-dating) employing 174 morphological characters of 73 Recent and 43 fossil taxa (48 families) and DNA sequences of three gene regions, to obtain divergence time estimates and compare the chronology of the most diverse lineage of scale insects, the neococcoid families, with the timing of the main angiosperm radiation. An estimated origin of the Coccomorpha occurred at the beginning of the Triassic, about 245 Ma [228–273], and of the neococcoids 60 million years later [210–165 Ma]. A total-evidence approach allows the integration of extinct scale insects into a phylogenetic framework, resulting in slightly younger median estimates than analyses using Recent taxa, calibrated with fossil ages only. From these estimates, we hypothesise that most major lineages of coccoids shifted from gymnosperms onto angiosperms when the latter became diverse and abundant in the mid- to Late Cretaceous. PMID:27000526

  3. Radiation protection in medicine: Ethical framework revisited

    International Nuclear Information System (INIS)

    The ethical framework within which medicine operates has changed radically over the last two decades. This has been stimulated by events leading to controversy, such as the infant organ retention scandals; concerns about blood products; self regulation of medical practice in the wake of the Harold Shipman Enquiry in the UK; and many other events. It has become obvious following investigations and/or public enquiries that a gap has opened up between what is acceptable to the public on the one hand, and what appears reasonable to, or is at least accepted by, the professionals involved on the other. This paper reviews these issues and some conclusions of a workshop held to consider them. It places the developments in the context of the idea that the approach to problems and communication in a group of people/professionals such as doctors, radiologists, radiation protection specialists, or even the general public may be regarded as a 'culture'. Current practice of radiation protection in medicine is examined in the light of these considerations. (authors)

  4. Early evolution of angiosperms

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ While many characters have been used to define the nature of the angiosperms in living plants, the list must be reduced to a single character that can be found in the fossil record in order to proceed with our search for the earliest flowering plants.

  5. Evolution of angiosperm seed disperser mutualisms: the timing of origins and their consequences for coevolutionary interactions between angiosperms and frugivores.

    Science.gov (United States)

    Eriksson, Ove

    2016-02-01

    The origins of interactions between angiosperms and fruit-eating seed dispersers have attracted much attention following a seminal paper on this topic by Tiffney (1984). This review synthesizes evidence pertaining to key events during the evolution of angiosperm-frugivore interactions and suggests some implications of this evidence for interpretations of angiosperm-frugivore coevolution. The most important conclusions are: (i) the diversification of angiosperm seed size and fleshy fruits commenced around 80 million years ago (Mya). The diversity of seed sizes, fruit sizes and fruit types peaked in the Eocene around 55 to 50 Mya. During this first phase of the interaction, angiosperms and animals evolving frugivory expanded into niche space not previously utilized by these groups, as frugivores and previously not existing fruit traits appeared. From the Eocene until the present, angiosperm-frugivore interactions have occurred within a broad frame of existing niche space, as defined by fruit traits and frugivory, motivating a separation of the angiosperm-frugivore interactions into two phases, before and after the peak in the early Eocene. (ii) The extinct multituberculates were probably the most important frugivores during the early radiation phase of angiosperm seeds and fleshy fruits. Primates and rodents are likely to have been important in the latter part of this first phase. (iii) Flying frugivores, birds and bats, evolved during the second phase, mainly during the Oligocene and Miocene, thus exploiting an existing diversity of fleshy fruits. (iv) A drastic climate shift around the Eocene-Oligocene boundary (around 34 Mya) resulted in more semi-open woodland vegetation, creating patchily occurring food resources for frugivores. This promoted evolution of a 'flying frugivore niche' exploited by birds and bats. In particular, passerines became a dominant frugivore group worldwide. (v) Fleshy fruits evolved at numerous occasions in many angiosperm families

  6. Radiative corrections to real and virtual muon Compton scattering revisited

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, N. [Physik-Department T39, Technische Universitaet Muenchen, D-85747 Garching (Germany)], E-mail: nkaiser@ph.tum.de

    2010-06-01

    We calculate in closed analytical form the one-photon loop radiative corrections to muon Compton scattering {mu}{sup -}{gamma}{yields}{mu}{sup -}{gamma}. Ultraviolet and infrared divergences are both treated in dimensional regularization. Infrared finiteness of the (virtual) radiative corrections is achieved (in the standard way) by including soft photon radiation below an energy cut-off {lambda}. We find that the anomalous magnetic moment {alpha}/2{pi} provides only a very small portion of the full radiative corrections. Furthermore, we extend our calculation of radiative corrections to the muon-nucleus bremsstrahlung process (or virtual muon Compton scattering {mu}{sup -}{gamma}{sub 0}*{yields}{mu}{sup -}{gamma}). These results are particularly relevant for analyzing the COMPASS experiment at CERN in which muon-nucleus bremsstrahlung serves to calibrate the Primakoff scattering of high-energy pions off a heavy nucleus with the aim of measuring the pion electric and magnetic polarizabilities. We find agreement with an earlier calculation of these radiative corrections based on a different method.

  7. Schmeissneria: A missing link to angiosperms?

    Directory of Open Access Journals (Sweden)

    Cui Jinzhong

    2007-02-01

    Full Text Available Abstract Background The origin of angiosperms has been under debate since the time of Darwin. While there has been much speculation in past decades about pre-Cretaceous angiosperms, including Archaefructus, these reports are controversial. The earliest reliable fossil record of angiosperms remains restricted to the Cretaceous, even though recent molecular phylogenetic studies suggest an origin for angiosperms much earlier than the current fossil record. Results In this paper, after careful SEM and light microscopic work, we report fossils with angiospermous traits of the Jurassic age. The fossils were collected from the Haifanggou Formation (middle Jurassic in western Liaoning, northeast China. They include two female structures and an associated leaf on the same slab. One of the female structures is physically connected to the apex of a short shoot. The female organs are borne in pairs on short peduncles that are arranged along the axis of the female structure. Each of the female organs has a central unit that is surrounded by an envelope with characteristic longitudinal ribs. Each central unit has two locules completely separated by a vertical septum. The apex of the central unit is completely closed. The general morphology places these fossils into the scope of Schmeissneria, an early Jurassic genus that was previously attributed to Ginkgoales. Conclusion Because the closed carpel is a character only found in angiosperms, the closed apex of the central unit suggests the presence of angiospermy in Schmeissneria. This angiospermous trait implies either a Jurassic angiosperm or a new seed plant group parallel to angiosperms and other known seed plants. As an angiosperm, the Liassic age (earliest Jurassic of Schmeissneria microstachys would suggest an origin of angiosperms during the Triassic. Although still uncertain, this could have a great impact on our perspective of the history, diversity and systematics of seed plants and angiosperms.

  8. Low-level radiation exposures: time to revisit linear no-threshold concept

    International Nuclear Information System (INIS)

    The concepts of LNT (Linear No-Threshold) and the resulting ALARA (As Low As Reasonably Achievable) used for radiological protection have been stumbling blocks for public acceptability of nuclear power. Often, public get confused and easily get exploited by interested people. The application of this concept has perhaps resulted in a more harmful phenomenon now known as 'radiophobia'. Over the years, LNT has become the corner stone of radiation protection philosophy for the international organizations like ICRP, UNSCEAR etc. which is followed by all national regulators. The genesis of these theories is the cellular level findings of half a century back. Most of these are findings at high dose levels in macro systems and extrapolated to low dose. It is time that international radiation safety organizations revisit the assumptions and have a more pragmatic approach towards these abstract concepts in the light of new findings. The article reviews the evolution of LNT hypothesis and the basis for LNT, examines the possibility that there might be a threshold dose, below which there would be no radiation-related cancer risk. Evidences against LNT and the possible existence of a threshold dose are reviewed. The article concludes that this is definitely time to have a re-look of the corner stone concepts in radiation protection philosophy. (author)

  9. Megastigmus seed chalcids (Hymenoptera, Torymidae) radiated much more on Angiosperms than previously considered. I- Description of 8 new species from Kenya, with a key to the females of Eastern and Southern Africa

    Science.gov (United States)

    Roques, Alain; Copeland, Robert S.; Soldati, Laurent; Denux, Olivier; Auger-Rozenberg, Marie-Anne

    2016-01-01

    Abstract A survey of seed chalcids from woody plants in Kenya revealed 12 species belonging to the genus Megastigmus Dalman, 1820, and has increased to 16 the number of Megastigmus species presently recorded from the Afrotropical Region, of which at least 13 are seed feeders. A key to female Megastigmus of the Afrotropical Region is provided. Eight new species are described from morphological evidence: Megastigmus lanneae Roques & Copeland, Megastigmus laventhali Roques & Copeland, Megastigmus ozoroae Roques & Copeland, and Megastigmus smithi Roques & Copeland in seeds of species of the family Anacardiaceae, Megastigmus copelandi Roques & Copeland and Megastigmus grewianae Roques & Copeland in seeds of Malvaceae, Megastigmus helinae Roques & Copeland in seeds of Rhamnaceae, and Megastigmus icipeensis Roques & Copeland for which no host is known. These collections include the first records of Malvaceae and Rhamnaceae as hosts of Megastigmus seed chalcids, which appear to have radiated in Angiosperms much more than previously considered. Analyses of the mitochondrial (cytochrome oxidase subunit one – COI) and nuclear DNA (28S ribosomal region) could be carried out on 8 of the 16 African species of which 5 were newly described ones. The species associated with Anacardiaceae always clustered together in phylogenies, confirming the existence of a strong and ancestral monophyletic clade, unlike the ones associated with Malvaceae and Rhamnaceae, whose position remains unclear. All holotypes are deposited in the National Museums of Kenya. PMID:27199604

  10. A combinatorial morphospace for angiosperm pollen

    Science.gov (United States)

    Mander, Luke

    2016-04-01

    The morphology of angiosperm (flowering plant) pollen is extraordinarily diverse. This diversity results from variations in the morphology of discrete anatomical components. These components include the overall shape of a pollen grain, the stratification of the exine, the number and form of any apertures, the type of dispersal unit, and the nature of any surface ornamentation. Different angiosperm pollen morphotypes reflect different combinations of these discrete components. In this talk, I ask the following question: given the anatomical components of angiosperm pollen that are known to exist in the plant kingdom, how many unique biologically plausible combinations of these components are there? I explore this question from the perspective of enumerative combinatorics using an algorithm I have written in the Python programming language. This algorithm (1) calculates the number of combinations of these components; (2) enumerates those combinations; and (3) graphically displays those combinations. The result is a combinatorial morphospace that reflects an underlying notion that the process of morphogenesis in angiosperm pollen can be thought of as an n choose k counting problem. I compare the morphology of extant and fossil angiosperm pollen grains to this morphospace, and suggest that from a combinatorial point of view angiosperm pollen is not as diverse as it could be, which may be a result of developmental constraints.

  11. Formation and development of sperms in angiosperms

    OpenAIRE

    S. Tatintseva

    2014-01-01

    Spermiogelnesis has been studied in a large number of Angiosperm species characterizing different levels of phylogenetic system. The formation and development of male gamets can be described as formation of sperm cells that undergo ontogenesis which stimulates changes up to full maturity of the pollen grain. The process of ontogenesis is aimed at creating a suitable delivery system by the pollen tube to a female gamete.

  12. Angiosperms, Los Tuxtlas Biosphere Reserve, Veracruz, Mexico

    OpenAIRE

    S. Mandujano; Dunn, J. C.; Benítez-Malvido, J.; Arroyo-Rodríguez, V.

    2009-01-01

    The Los Tuxtlas Reserve has been heavily deforested and fragmented since the 1970’s. Although the floraof Los Tuxtlas has been described previously, most floristic lists come from the large forest reserve of the Los Tuxtlasfield station. Here we present a check list of Angiosperms recorded in 45 rainforest fragments (< 1 to 266 ha) located inthree landscapes with different levels of deforestation. We sampled all trees, shrubs, lianas, palms and herbs withdiameter at breast height (dbh)

  13. Angiosperms, Los Tuxtlas Biosphere Reserve, Veracruz, Mexico

    Directory of Open Access Journals (Sweden)

    Mandujano, S.

    2009-01-01

    Full Text Available The Los Tuxtlas Reserve has been heavily deforested and fragmented since the 1970’s. Although the floraof Los Tuxtlas has been described previously, most floristic lists come from the large forest reserve of the Los Tuxtlasfield station. Here we present a check list of Angiosperms recorded in 45 rainforest fragments (< 1 to 266 ha located inthree landscapes with different levels of deforestation. We sampled all trees, shrubs, lianas, palms and herbs withdiameter at breast height (dbh

  14. The Early Flowers and Angiosperm Evolution

    DEFF Research Database (Denmark)

    Friis, Else Marie; Crane, P.R.; Pedersen, Kaj Raunsgaard

    based on research into Early and Late Cretaceous fossil floras from Europe and North America, the authors draw on direct palaeontological evidence of the pattern of angiosperm evolution through time. Synthesising palaeobotanical data with information from living plants, this unique book explores the...... evolutionary history of flowering plants from their earliest phases in obscurity to their dominance in modern vegetation. The discussion provides comprehensive biological and geological background information, before moving on to summarise the fossil record in detail. Including previously unpublished results...

  15. Ectomycorrhizas from a Lower Eocene angiosperm forest.

    Science.gov (United States)

    Beimforde, Christina; Schäfer, Nadine; Dörfelt, Heinrich; Nascimbene, Paul C; Singh, Hukam; Heinrichs, Jochen; Reitner, Joachim; Rana, Rajendra S; Schmidt, Alexander R

    2011-12-01

    The development of mycorrhizal associations is considered a key innovation that enabled vascular plants to extensively colonize terrestrial habitats. Here, we present the first known fossil ectomycorrhizas from an angiosperm forest. Our fossils are preserved in a 52 million-yr-old piece of amber from the Tadkeshwar Lignite Mine of Gujarat State, western India. The amber was produced by representatives of Dipterocarpaceae in an early tropical broadleaf forest. The ectomycorrhizas were investigated using light microscopy and field emission scanning electron microscopy. Dissolving the amber surrounding one of the fossils allowed ultrastructural analyses and Raman spectroscopy. Approx. 20 unramified, cruciform and monopodial-pinnate ectomycorrhizas are fossilized adjacent to rootlets, and different developmental stages of the fossil mycorrhizas are delicately preserved in the ancient resin. Compounds of melanins were detectable in the dark hyphae. The mycobiont, Eomelanomyces cenococcoides gen. et spec. nov., is considered to be an ascomycete; the host is most likely a dipterocarp representative. An early ectomycorrhizal association may have conferred an evolutionary advantage on dipterocarps. Our find indicates that ectomycorrhizas occurred contemporaneously within both gymnosperms (Pinaceae) and angiosperms (Dipterocarpaceae) by the Lower Eocene. PMID:22074339

  16. Solar radiation trend across China in recent decades: a revisit with quality-controlled data

    Directory of Open Access Journals (Sweden)

    W.-J. Tang

    2011-01-01

    Full Text Available Solar radiation is one of the most important factors affecting climate and environment, and its long-term variation is of much concern in climate change studies. In the light of the limited number of radiation stations with reliable long-term time series observations, this paper presents a new evaluation of the long-term variation of surface solar radiation over China by combining quality-controlled observed data and two radiation models. One is the ANN-based (Artificial Neutral Network model and the other is a physical model. The two models produce radiation trends comparable to the observed ones at a few validation stations possessing reliable and continuous data. Then, the trend estimate is extended by the ANN-based model to all 96 radiation stations and furthermore extended by the physical model to all 716 China Meteorological Administration (CMA routine stations. The new trend estimate is different from previous ones in two aspects. First, the magnitude of solar radiation over China decreased by about −0.23 W m−2 yr−1 between 1961 and 2000, which is greatly less in magnitude than trend slopes estimated in previous studies (ranging over −0.41 ~ −0.52 W m−2 yr−1. Second, the "From Dimming to Brightening" transition in China during the late 1980s ~ the early 1990s was addressed in previous studies, but this study indicates the solar radiation reached a stable level since the 1990s and the transition is not noticeable. These differences indicate the importance of data-quality control and analysis approaches. Finally, an obvious transition from brightening to dimming around 1978 is found over the Tibetan Plateau, where aerosol loads are very low, indicating that the importance of cloud changes in altering solar radiation may be comparable to that of the aerosol changes.

  17. Classical Zero-Point Radiation and Relativity: The Problem of Atomic Collapse Revisited

    Science.gov (United States)

    Boyer, Timothy H.

    2016-07-01

    The physicists of the early twentieth century were unaware of two aspects which are vital to understanding some aspects of modern physics within classical theory. The two aspects are: (1) the presence of classical electromagnetic zero-point radiation, and (2) the importance of special relativity. In classes in modern physics today, the problem of atomic collapse is still mentioned in the historical context of the early twentieth century. However, the classical problem of atomic collapse is currently being treated in the presence of classical zero-point radiation where the problem has been transformed. The presence of classical zero-point radiation indeed keeps the electron from falling into the Coulomb potential center. However, the old collapse problem has been replaced by a new problem where the zero-point radiation may give too much energy to the electron so as to cause "self-ionization." Special relativity may play a role in understanding this modern variation on the atomic collapse problem, just as relativity has proved crucial for a classical understanding of blackbody radiation.

  18. Classical Zero-Point Radiation and Relativity: The Problem of Atomic Collapse Revisited

    Science.gov (United States)

    Boyer, Timothy H.

    2016-05-01

    The physicists of the early twentieth century were unaware of two aspects which are vital to understanding some aspects of modern physics within classical theory. The two aspects are: (1) the presence of classical electromagnetic zero-point radiation, and (2) the importance of special relativity. In classes in modern physics today, the problem of atomic collapse is still mentioned in the historical context of the early twentieth century. However, the classical problem of atomic collapse is currently being treated in the presence of classical zero-point radiation where the problem has been transformed. The presence of classical zero-point radiation indeed keeps the electron from falling into the Coulomb potential center. However, the old collapse problem has been replaced by a new problem where the zero-point radiation may give too much energy to the electron so as to cause "self-ionization." Special relativity may play a role in understanding this modern variation on the atomic collapse problem, just as relativity has proved crucial for a classical understanding of blackbody radiation.

  19. The leaded apron revisited: does it reduce gonadal radiation dose in dental radiology

    Energy Technology Data Exchange (ETDEWEB)

    Wood, R.E.; Harris, A.M.; van der Merwe, E.J.; Nortje, C.J. (Ontario Cancer Institute, Princess Margaret Hospital, Toronto (Canada))

    1991-05-01

    A tissue-equivalent anthropomorphic human phantom was used with a lithium fluoride thermoluminescent dosimetry system to evaluate the radiation absorbed dose to the ovarian and testicular region during dental radiologic procedures. Measurements were made with and without personal lead shielding devices consisting of thyroid collar and apron of 0.25 mm lead thickness equivalence. The radiation absorbed dose with or without lead shielding did not differ significantly from control dosimeters in vertex occlusal and periapical views (p greater than 0.05). Personal lead shielding devices did reduce gonadal dose in the case of accidental exposure (p less than 0.05). A leaded apron of 0.25 mm lead thickness equivalent was permeable to radiation in direct exposure testing.

  20. The leaded apron revisited: does it reduce gonadal radiation dose in dental radiology

    International Nuclear Information System (INIS)

    A tissue-equivalent anthropomorphic human phantom was used with a lithium fluoride thermoluminescent dosimetry system to evaluate the radiation absorbed dose to the ovarian and testicular region during dental radiologic procedures. Measurements were made with and without personal lead shielding devices consisting of thyroid collar and apron of 0.25 mm lead thickness equivalence. The radiation absorbed dose with or without lead shielding did not differ significantly from control dosimeters in vertex occlusal and periapical views (p greater than 0.05). Personal lead shielding devices did reduce gonadal dose in the case of accidental exposure (p less than 0.05). A leaded apron of 0.25 mm lead thickness equivalent was permeable to radiation in direct exposure testing

  1. Revisiting the interplay between ablation, collisional, and radiative processes during ns-laser ablation

    International Nuclear Information System (INIS)

    A study of ns-laser ablation is presented, which focuses on the transient behavior of the physical processes that act in and above a copper sample. A dimensionless multiphase collisional radiative model describes the interplay between the ablation, collisional, and radiative mechanisms. Calculations are done for a 6 ns-Nd:YAG laser pulse operating at 532 nm and fluences up to 15 J/cm2. Temporal intensity profiles as well as transmissivities are in good agreement with experimental results. It is found that volumetric ablation mechanisms and photo-processes both play an essential role in the onset of ns-laser induced breakdown

  2. Classical Zero-Point Radiation and Relativity: The Problem of Atomic Collapse Revisited

    CERN Document Server

    Boyer, Timothy H

    2015-01-01

    The physicists of the early 20th century were unaware of two aspects which are vital to understanding some aspects of modern physics within classical theory. The two aspects are: 1) the presence of classical electromagnetic zero-point radiation, and 2) the importance of special relativity. In classes in modern physics today, the problem of atomic collapse is still mentioned in the historical context of the early 20th century. However, the classical problem of atomic collapse is currently being treated in the presence of classical zero-point radiation where the problem has been transformed. The presence of classical zero-point radiation indeed keeps the electron from falling into the Coulomb potential center. However, the old collapse problem has been replaced by a new problem where the zero-point radiation may give too much energy to the electron so as to cause self-ionization. Special relativity may play a role in understanding this modern variation on the atomic collapse problem, just as relativity has prov...

  3. Design of biomimetic camouflage materials based on angiosperm leaf organs

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The micro structures and reflectance spectra of angiosperm leaves were compared with those of angiosperm petals. The study indicated that angiosperm leaf organs had identical micro structures and reflectance characteristics in the wave band of near infrared. Micro structures and compositions of leaf organs were the crucial factors influencing their reflectance spectra. The model of biomimetic materials based on angiosperm leaf organs was introduced and verified. From 300 to 2600 nm, the similarity coefficients of reflectance spectra of the foam containing water and Platanus Orientalis Linn. leaves were all above 0.969. The biomimetic camou- flage material exhibited almost the same reflectance spectra with those of green leaves in ultraviolet, visible and near infrared wave bands. And its "concolor and conspectrum" effect might take on reconnaissance of hyperspectral and ultra hy- perspectral imaging.

  4. Why does biparental plastid inheritance revive in angiosperms?

    Science.gov (United States)

    Zhang, Quan; Sodmergen

    2010-03-01

    It is widely believed that plastid and mitochondrial genomes are inherited through the maternal parent. In plants, however, paternal transmission of these genomes is frequently observed, especially for the plastid genome. A male gametic trait, called potential biparental plastid inheritance (PBPI), occurs in up to 20% of angiosperm genera, implying a strong tendency for plastid transmission from the male lineage. Why do plants receive organelles from the male parents? Are there clues in plastids that will help to elucidate the evolution of plants? Reconstruction of the ancestral state of plastid inheritance patterns in a phylogenetic context provides insights into these questions. In particular, a recent report demonstrated the unilateral occurrence of PBPI in angiosperms. This result implies that nuclear cytoplasmic conflicts, a basic driving force for altering the mode of organelle inheritance, might have arisen specifically in angiosperms. Based on existing evidence, it is likely that biparental inheritance may have occurred to rescue angiosperm species with defective plastids. PMID:20052516

  5. Angiosperms additions to flora of Peru

    Directory of Open Access Journals (Sweden)

    Eric F. Rodríguez

    2006-10-01

    Full Text Available We present here 131 new additions to the angiosperm flora of Peru from recent collections in the north of Peru, mostly from department of Amazonas (provinces of Bagua and Condorcanqui and department of Cajamarca (province of San Ignacio. This new contribution is the result of field and herbarium studies by the various authors in this region from 1993 to 2002, and represents the combined effort of personnel from the Herbarium Truxillense (HUT and the Herbarium of the Missouri Botanical Garden (MO as part of the Flora of Peru Project. The species reported here were compared against the list of species documented in the «Catalogue of Flowering Plants and Gymnosperms of Peru» (Brako & Zarucchi, 1993 and «Ten years of additions to the flora of Peru: 1993- 2003» (Ulloa Ulloa et al., 2004. The new taxa are organized in three categories: 18 species new to science, six new nomenclatural combinations and 107 new records, thereby enlarging their geographical distribution towards to Peru. Considering the new species and the new records, this contribution adds 125 species to the Peruvian Flora.

  6. Angiosperm phylogeny inferred from sequences of four mitochondrial genes

    Institute of Scientific and Technical Information of China (English)

    Yin-Long QIU; Zhi-Duan CHEN; Libo LI; Bin WANG; Jia-Yu XUE; Tory A. HENDRY; Rui-Qi LI; Joseph W. BROWN; Yang LIU; Geordan T. HUDSON

    2010-01-01

    An angiosperm phylogeny was reconstructed in a maximum likelihood analysis of sequences of four mitochondrial genes, atpl, matR, had5, and rps3, from 380 species that represent 376 genera and 296 families of seed plants. It is largely congruent with the phylogeny of angiosperms reconstructed from chloroplast genes atpB, matK, and rbcL, and nuclear 18S rDNA. The basalmost lineage consists of Amborella and Nymphaeales (including Hydatellaceae). Austrobaileyales follow this clade and are sister to the mesangiosperms, which include Chloranthaceae, Ceratophyllum, magnoliids, monocots, and eudicots. With the exception of Chloranthaceae being sister to Ceratophyllum, relationships among these five lineages are not well supported. In eudicots, Ranunculales, Sabiales, Proteales, Trochodendrales, Buxales, Gunnerales, Saxifragales, Vitales, Berberidopsidales, and Dilleniales form a basal grade of lines that diverged before the diversification of rosids and asterids. Within rosids, the COM (Celastrales-Oxalidales-Malpighiales) clade is sister to malvids (or rosid Ⅱ), instead of to the nitrogen-fixing clade as found in all previous large-scale molecular analyses of angiosperms. Santalales and Caryophyllales are members of an expanded asterid clade. This study shows that the mitochondrial genes are informative markers for resolving relationships among genera, families, or higher rank taxa across angiosperms. The low substitution rates and low homoplasy levels of the mitochondrial genes relative to the chloroplast genes, as found in this study, make them particularly useful for reconstructing ancient phylogenetic relationships. A mitochondrial gene-based angiosperm phylogeny provides an independent and essential reference for comparison with hypotheses of angiosperm phylogeny based on chloroplast genes, nuclear genes, and non-molecular data to reconstruct the underlying organismal phylogeny.

  7. STUDY OF AQUATIC ANGIOSPERMIC PLANTS OF ANAND CITY, GUJARAT, INDIA

    Directory of Open Access Journals (Sweden)

    K. R. PATEL1 AND N. K. PATEL2

    2014-06-01

    Full Text Available The present study deals with the taxonomic study of Aquatic Angiosperms growing throughout the Anand city. The plants are listed along with their brief taxonomic account of each species with current nomenclature, vernacular name, family and uses. The  collected plants are systematically observed during present work, During my study I observed various aquatic angiospermic plants such as   Ceratophyllum demersum, Colocasia esculenta, Eichhornia crassipes, Ipomoea aquatica, Nymphoides indicum, Ludwigia repens, Polygonum orientale, Typha elephantina, Lemna perpusilla, Spirodella polyrrhiza, Xanthium indicum, Phyllanthus reticulatus, Cynodon dactylon, Hydrilla verticillata were very common. Whereas Nymphaea nouchali, Polygonum barbatum, Scirpus articulatus were very rare in the study area.

  8. Recalibrated tree of leaf beetles (Chrysomelidae indicates independent diversification of angiosperms and their insect herbivores.

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    Jesús Gómez-Zurita

    Full Text Available BACKGROUND: The great diversity of the "Phytophaga" (weevils, longhorn beetles and leaf beetles has been attributed to their co-radiation with the angiosperms based on matching age estimates for both groups, but phylogenetic information and molecular clock calibrations remain insufficient for this conclusion. METHODOLOGY: A phylogenetic analysis of the leaf beetles (Chrysomelidae was conducted based on three partial ribosomal gene markers (mitochondrial rrnL, nuclear small and large subunit rRNA including over 3000 bp for 167 taxa representing most major chrysomelid lineages and outgroups. Molecular clock calibrations and confidence intervals were based on paleontological data from the oldest (K-T boundary leaf beetle fossil, ancient feeding traces ascribed to hispoid Cassidinae, and the vicariant split of Nearctic and Palearctic members of the Timarchini. PRINCIPAL FINDINGS: The origin of the Chrysomelidae was dated to 73-79 Mya (confidence interval 63-86 Mya, and most subfamilies were post-Cretaceous, consistent with the ages of all confirmed body fossils. Two major monocot feeding chrysomelid lineages formed widely separated clades, demonstrating independent colonization of this ancient (early Cretaceous angiosperm lineage. CONCLUSIONS: Previous calibrations proposing a much older origin of Chrysomelidae were not supported. Therefore, chrysomelid beetles likely radiated long after the origin of their host lineages and their diversification was driven by repeated radiaton on a pre-existing diverse resource, rather than ancient host associations.

  9. The Pace and Shape of Senescence in Angiosperms

    DEFF Research Database (Denmark)

    Baudisch, Annette; Salguero-Gómez, Roberto; Jones, Owen; Wrycza, Tomasz; Mbeau-Ache, Cyril; Franco, Miguel; Colchero, Fernando

    2013-01-01

    phylogenetic relationships using a resolved supertree. 4. In contrast to the animal kingdom, most angiosperms (93%) show no senescence. Senescence is observed among phanerophytes (i.e. trees), but not among any other growth form (e.g. epiphytes, chamaephytes or cryptopyhtes). Yet, most phanerophytes (81%) do...

  10. Evolutionary aspects of life forms in angiosperm families

    NARCIS (Netherlands)

    Kremer, P; VanAndel, J

    1995-01-01

    The distribution patterns of life forms among extant families, subclasses and classes are described with the aim of detecting evolutionary trends. The explosive diversification of angiosperms constrains the possibilities for detecting such trends. Moreover, the extant groups of seed plants are only

  11. Lakatos Revisited.

    Science.gov (United States)

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social sciences as…

  12. Epiphytic leafy liverworts diversified in angiosperm-dominated forests

    Science.gov (United States)

    Feldberg, Kathrin; Schneider, Harald; Stadler, Tanja; Schäfer-Verwimp, Alfons; Schmidt, Alexander R.; Heinrichs, Jochen

    2014-08-01

    Recent studies have provided evidence for pulses in the diversification of angiosperms, ferns, gymnosperms, and mosses as well as various groups of animals during the Cretaceous revolution of terrestrial ecosystems. However, evidence for such pulses has not been reported so far for liverworts. Here we provide new insight into liverwort evolution by integrating a comprehensive molecular dataset with a set of 20 fossil age constraints. We found evidence for a relative constant diversification rate of generalistic liverworts (Jungermanniales) since the Palaeozoic, whereas epiphytic liverworts (Porellales) show a sudden increase of lineage accumulation in the Cretaceous. This difference is likely caused by the pronounced response of Porellales to the ecological opportunities provided by humid, megathermal forests, which were increasingly available as a result of the rise of the angiosperms.

  13. Angiosperm polyploids and their road to evolutionary success

    OpenAIRE

    Fawcett, Jeffrey A.; Van de Peer, Yves; Jeffrey A, FAWCETT

    2010-01-01

    The abundance of polyploidy among flowering plants has long been recognized, and recent studies have uncovered multiple ancient polyploidization events in the evolutionary history of several angiosperm lineages. Once polyploids are formed they must get locally established and then propagate and survive while adapting to different environments and avoiding extinction. This might ultimately lead to their long-term evolutionary success, where their descendant lineages survive for tens of million...

  14. Role of proline and GABA in sexual reproduction of angiosperms

    OpenAIRE

    Biancucci, Marco; Mattioli, Roberto; Forlani, Giuseppe; Funck, Dietmar; Costantino, Paolo; Trovato, Maurizio

    2015-01-01

    Two glutamate derivatives, proline and γ-aminobutyric acid (GABA), appear to play pivotal roles in different aspects of sexual reproduction in angiosperms, although their precise function in plant reproduction and the molecular basis of their action are not yet fully understood. Proline and GABA have long been regarded as pivotal amino acids in pollen vitality and fertility. Proline may constitute up to 70% of the free amino acid pool in pollen grains and it has been recently shown that Arabi...

  15. Sensemaking Revisited

    DEFF Research Database (Denmark)

    Holt, Robin; Cornelissen, Joep

    2014-01-01

    We critique and extend theory on organizational sensemaking around three themes. First, we investigate sense arising non-productively and so beyond any instrumental relationship with things; second, we consider how sense is experienced through mood as well as our cognitive skills of manipulation ...... research by revisiting Weick’s seminal reading of Norman Maclean’s book surrounding the tragic events of a 1949 forest fire at Mann Gulch, USA....

  16. New universal matK primers for DNA barcoding angiosperms

    Institute of Scientific and Technical Information of China (English)

    Jing YU; Jian-Hua XUE; Shi-Liang ZHOU

    2011-01-01

    The chloroplast maturase K gene (matK) is one of the most variable coding genes of angiosperms and has been suggested to be a "barcode" for land plants. However, matK exhibits low amplification and sequencing rates due to low universality of currently available primers and mononucleotide repeats. To resolve these technical problems, we evaluated the entire matK region to find a region of 600-800 bp that is highly variable, represents the best of all matK regions with priming sites conservative enough to design universal primers, and avoids the mononucleotide repeats. After careful evaluation, a region in the middle was chosen and a pair of primers named natK472F and matK1248R was designed to amplify and sequence the matK fragment of approximately 776 bp. This region encompasses the most variable sites, represents the entire matK region best, and also exhibits high amplification rates and quality of sequences. The universality of this primer pair was tested using 58 species from 47 families of angiosperm plants. The primers showed a strong amplification (93.1%) and sequencing (92.6%)successes in the species tested. We propose that the new primers will solve, in part, the problems encountered when using matK and promote the adoption of matK as a DNA barcode for angiosperms.

  17. ERBE Wide-Field-of-View Nonscanner Data Reprocessing and revisiting its Radiation dataset from 1985 to 199

    Science.gov (United States)

    Shrestha, A. K.; Kato, S.; Wong, T.; Stackhouse, P. W.; Rose, F. G.; Miller, W. F.; Bush, K.; Rutan, D. A.; Minnis, P.; Doelling, D.

    2015-12-01

    The Earth's radiation budget is a fundamental component of the climate system and should reflect the variation in climate. As such, it is critical to know how it has varied over past decades to ensure that climate models are properly representing climate. Broadband shortwave and longwave irradiances were measured by the Earth Radiation Budget Experiment (ERBE) wide-field-of-view (WFOV) nonscanner instrument from 1985 to 1998. These WFOV nonscanner instruments were onboard NASA's Earth Radiation Budget Satellite (ERBS) and two NOAA's satellites (NOAA-9 and NOAA-10). However, earlier studies showed that the transmissivity of the dome for the WFOV shortwave (SW) nonscanner instrument degraded over time. To account for the degradation, WFOV instruments were calibrated assuming constant spectral degradation (gray assumption). Recent developments from analysis of data from the Clouds and the Earth's Radiant Energy System project (CERES), which has been measuring the radiation budget since 2000, suggest that transmissivity of shorter wavelength degrades faster. Therefore, a spectrally dependent degradation correction is needed for a better calibration. In addition, accounting for the spectrally dependent degradation may eliminate an additional correction applied to irradiances using a time series of daytime and nighttime longwave irradiance differences. Therefore, we have reprocessed WFOV nonscanner data by characterizing the spectrally dependent degradation of the SW dome transmissivity. Time and spectral dependent degradation of the shortwave filter function is estimated using solar data observed by these instruments during calibration days. Because the spectrum of reflected irradiance depends on scene type, we use Advanced Very High Resolution Radiometer AVHRR-derived cloud properties and surface type over the WFOV footprints in addition to time dependent filter function for the unfiltering process. This poster explains the reprocessing approach and discusses the

  18. Endophytic bacterial community of a Mediterranean marine angiosperm (Posidonia oceanica

    Directory of Open Access Journals (Sweden)

    Neus eGarcias-Bonet

    2012-09-01

    Full Text Available Bacterial endophytes are crucial for the survival of many terrestrial plants, but little is known about the presence and importance of bacterial endophytes of marine plants. We conducted a survey of the endophytic bacterial community of the long-living Mediterranean marine angiosperm Posidonia oceanica in surface-sterilized tissues (roots, rhizomes and leaves by DGGE. A total of 26 Posidonia oceanica meadows around the Balearic Islands were sampled, and the band patterns obtained for each meadow were compared for the three sampled tissues. Endophytic bacterial sequences were detected in most of the samples analyzed. A total of 34 OTUs (Operational Taxonomic Units were detected. The main OTUs of endophytic bacteria present in P. oceanica tissues belonged primarily to Proteobacteria (α, γ and δ subclasses and Bacteroidetes. The OTUs found in roots significantly differed from those of rhizomes and leaves. Moreover, some OTUs were found to be associated to each type of tissue. Bipartite network analysis revealed differences in the bacterial endophyte communities present on different islands. The results of this study provide a pioneering step toward the characterization of the endophytic bacterial community associated with tissues of a marine angiosperm and reveal the presence of bacterial endophytes that differed among locations and tissue types.

  19. The 'Combi Fly Concept' revisited: How much radiation is required to sterilise males of a genetic sexing strain?

    International Nuclear Information System (INIS)

    In the 'Combi Fly Concept', as proposed by Steffens (1982, 1983), the radiation dose necessary to sterilise males can be reduced if the males carry a translocation between the male determining chromosome (Y) and an autosome. Such a chromosome rearrangement is required in genetic sexing strains (GSS) to link a selectable marker to sex. Due to the translocation, GSS males are already partially sterile and it might be possible to use a lower dose to sterilise them for release in SIT programmes. An added bonus to this approach is that this partial sterility is inherited by males. A reduction in radiation dose would be desirable because it would increase the quality of the insect

  20. The gravitational wave radiation of pulsating white dwarfs revisited: the case of BPM 37093 and PG 1159-035

    CERN Document Server

    García-Berro, E; Corsico, A H; Althaus, L G; Lobo, J A; Isern, J

    2005-01-01

    We compute the emission of gravitational radiation from pulsating white dwarfs. This is done by using an up-to-date stellar evolutionary code coupled with a state-of-the-art pulsational code. The emission of gravitational waves is computed for a standard 0.6 solar masses white dwarf with a liquid carbon-oxygen core and a hydrogen-rich envelope, for a massive DA white dwarf with a partially crystallized core for which various l=2 modes have been observed (BPM 37093) and for PG 1159-035, the prototype of the GW Vir class of variable stars, for which several quadrupole modes have been observed as well. We find that these stars do not radiate sizeable amounts of gravitational waves through their observed pulsation g-modes, in line with previous studies. We also explore the possibility of detecting gravitational waves radiated by the f-mode and the p-modes. We find that in this case the gravitational wave signal is very large and, hence, the modes decay very rapidly. We also discuss the possible implications of ou...

  1. Floral gene resources from basal angiosperms for comparative genomics research

    Directory of Open Access Journals (Sweden)

    Zhang Xiaohong

    2005-03-01

    Full Text Available Abstract Background The Floral Genome Project was initiated to bridge the genomic gap between the most broadly studied plant model systems. Arabidopsis and rice, although now completely sequenced and under intensive comparative genomic investigation, are separated by at least 125 million years of evolutionary time, and cannot in isolation provide a comprehensive perspective on structural and functional aspects of flowering plant genome dynamics. Here we discuss new genomic resources available to the scientific community, comprising cDNA libraries and Expressed Sequence Tag (EST sequences for a suite of phylogenetically basal angiosperms specifically selected to bridge the evolutionary gaps between model plants and provide insights into gene content and genome structure in the earliest flowering plants. Results Random sequencing of cDNAs from representatives of phylogenetically important eudicot, non-grass monocot, and gymnosperm lineages has so far (as of 12/1/04 generated 70,514 ESTs and 48,170 assembled unigenes. Efficient sorting of EST sequences into putative gene families based on whole Arabidopsis/rice proteome comparison has permitted ready identification of cDNA clones for finished sequencing. Preliminarily, (i proportions of functional categories among sequenced floral genes seem representative of the entire Arabidopsis transcriptome, (ii many known floral gene homologues have been captured, and (iii phylogenetic analyses of ESTs are providing new insights into the process of gene family evolution in relation to the origin and diversification of the angiosperms. Conclusion Initial comparisons illustrate the utility of the EST data sets toward discovery of the basic floral transcriptome. These first findings also afford the opportunity to address a number of conspicuous evolutionary genomic questions, including reproductive organ transcriptome overlap between angiosperms and gymnosperms, genome-wide duplication history, lineage

  2. Rapid and accurate pyrosequencing of angiosperm plastid genomes

    Directory of Open Access Journals (Sweden)

    Farmerie William G

    2006-08-01

    Full Text Available Abstract Background Plastid genome sequence information is vital to several disciplines in plant biology, including phylogenetics and molecular biology. The past five years have witnessed a dramatic increase in the number of completely sequenced plastid genomes, fuelled largely by advances in conventional Sanger sequencing technology. Here we report a further significant reduction in time and cost for plastid genome sequencing through the successful use of a newly available pyrosequencing platform, the Genome Sequencer 20 (GS 20 System (454 Life Sciences Corporation, to rapidly and accurately sequence the whole plastid genomes of the basal eudicot angiosperms Nandina domestica (Berberidaceae and Platanus occidentalis (Platanaceae. Results More than 99.75% of each plastid genome was simultaneously obtained during two GS 20 sequence runs, to an average depth of coverage of 24.6× in Nandina and 17.3× in Platanus. The Nandina and Platanus plastid genomes shared essentially identical gene complements and possessed the typical angiosperm plastid structure and gene arrangement. To assess the accuracy of the GS 20 sequence, over 45 kilobases of sequence were generated for each genome using conventional sequencing. Overall error rates of 0.043% and 0.031% were observed in GS 20 sequence for Nandina and Platanus, respectively. More than 97% of all observed errors were associated with homopolymer runs, with ~60% of all errors associated with homopolymer runs of 5 or more nucleotides and ~50% of all errors associated with regions of extensive homopolymer runs. No substitution errors were present in either genome. Error rates were generally higher in the single-copy and noncoding regions of both plastid genomes relative to the inverted repeat and coding regions. Conclusion Highly accurate and essentially complete sequence information was obtained for the Nandina and Platanus plastid genomes using the GS 20 System. More importantly, the high accuracy

  3. Fossil evidence for a herbaceous diversification of early eudicot angiosperms during the Early Cretaceous.

    Science.gov (United States)

    Jud, Nathan A

    2015-09-01

    Eudicot flowering plants comprise roughly 70% of land plant species diversity today, but their early evolution is not well understood. Fossil evidence has been largely restricted to their distinctive tricolpate pollen grains and this has limited our understanding of the ecological strategies that characterized their primary radiation. I describe megafossils of an Early Cretaceous eudicot from the Potomac Group in Maryland and Virginia, USA that are complete enough to allow reconstruction of important life-history traits. I draw on quantitative and qualitative analysis of functional traits, phylogenetic analysis and sedimentological evidence to reconstruct the biology of this extinct species. These plants were small and locally rare but widespread, fast-growing herbs. They had complex leaves and they were colonizers of bright, wet, disturbance-prone habitats. Other early eudicot megafossils appear to be herbaceous rather than woody, suggesting that this habit was characteristic of their primary radiation. A mostly herbaceous initial diversification of eudicots could simultaneously explain the heretofore sparse megafossil record as well as their rapid diversification during the Early Cretaceous because the angiosperm capacity for fast reproduction and fast evolution is best expressed in herbs. PMID:26336172

  4. Revisiting the health effects of psychological stress—its influence on susceptibility to ionizing radiation: a mini-review

    Science.gov (United States)

    Wang, Bing; Katsube, Takanori; Begum, Nasrin; Nenoi, Mitsuru

    2016-01-01

    Both psychological stress (PS) and ionizing radiation (IR) cause varied detrimental effects on humans. There has been no direct evidence so far showing PS alone could cause cancer; however, long-lasting PS may affect our overall health and ability to cope with cancer. Due to their living conditions and occupations, some people may encounter concurrent exposure to both PS and IR to a high extent. In addition to possible health effects resulting directly from exposure to IR on these people, fear of IR exposure is also a cause of PS. The question of whether PS would influence susceptibility to IR, radiocarcinogenesis in particular, is of great concern by both the academic world and the public. Recently, investigations using animal PS models demonstrated that PS could modulate susceptibility to IR, causing increased susceptibility to radiocarcinogenesis in Trp53-heterozygous mice, hematological toxicity in peripheral blood and elevated chromosome aberration (dicentrics) frequency in splenocytes of Trp53–wild-type mice. To actively reduce health risk from exposure to IR, further studies are needed to cumulate more evidence and provide insights into the mechanisms underlying the alterations in susceptibility due to PS modulation. This mini-review gives a general overview of the significance of PS effects on humans and experimental animals, with a special focus on summarizing the latest weight-of-evidence approaches to radiobiological studies on PS-induced alterations in susceptibility in experimental animal models. The susceptibility being investigated is mainly in the context of the impact of the modulatory effect of PS on radiocarcinogenesis; we seek to improve understanding of the combined effects of exposure to both PS and IR in order to facilitate, via active intervention, strategies for radiation risk reduction. PMID:27242342

  5. Cellulose Orientation in the Outer Epidermal Wall of Angiosperm Roots: Implications for Biosystematics

    OpenAIRE

    KERSTENS, SVEN; VERBELEN, JEAN‐PIERRE

    2002-01-01

    The net orientation of cellulose fibrils in the outer epidermal wall of the root elongation zone of 57 angiosperm species belonging to 29 families was determined by means of Congo Red fluorescence and polarization confocal microscopy. The angiosperms can be divided in three groups. In all but four plant families, the net orientation of the cellulose fibrils is transverse to the root axis. Three families, the Poaceae, Juncaceae and Cyperaceae, have a totally different organization. In the root...

  6. Unique responsiveness of angiosperm stomata to elevated CO2 explained by calcium signalling.

    Directory of Open Access Journals (Sweden)

    Timothy J Brodribb

    Full Text Available Angiosperm and conifer tree species respond differently when exposed to elevated CO2, with angiosperms found to dynamically reduce water loss while conifers appear insensitive. Such distinct responses are likely to affect competition between these tree groups as atmospheric CO2 concentration rises. Seeking the mechanism behind this globally important phenomenon we targeted the Ca(2+-dependent signalling pathway, a mediator of stomatal closure in response to elevated CO2, as a possible explanation for the differentiation of stomatal behaviours. Sampling across the diversity of vascular plants including lycophytes, ferns, gymnosperms and angiosperms we show that only angiosperms possess the stomatal behaviour and prerequisite genetic coding, linked to Ca(2+-dependent stomatal signalling. We conclude that the evolution of Ca(2+-dependent stomatal signalling gives angiosperms adaptive benefits in terms of highly efficient water use, but that stomatal sensitivity to high CO2 may penalise angiosperm productivity relative to other plant groups in the current era of soaring atmospheric CO2.

  7. Role of proline and GABA in sexual reproduction of angiosperms.

    Science.gov (United States)

    Biancucci, Marco; Mattioli, Roberto; Forlani, Giuseppe; Funck, Dietmar; Costantino, Paolo; Trovato, Maurizio

    2015-01-01

    Two glutamate derivatives, proline and γ-aminobutyric acid (GABA), appear to play pivotal roles in different aspects of sexual reproduction in angiosperms, although their precise function in plant reproduction and the molecular basis of their action are not yet fully understood. Proline and GABA have long been regarded as pivotal amino acids in pollen vitality and fertility. Proline may constitute up to 70% of the free amino acid pool in pollen grains and it has been recently shown that Arabidopsis mutants affected in the first and rate-limiting step in proline synthesis produce aberrant and infertile pollen grains, indicating that proline synthesis is required for pollen development and fertility. Concerning GABA, a large body of evidence points to this glutamate derivative as a key determinant of post-pollination fertilization. Intriguingly, proline has also been associated with pollination, another aspect of sexual reproduction, since honeybees were reported to show a strong preference for proline-enriched nectars. In this review, we survey current knowledge on the roles of proline and GABA in plant fertility, and discuss future perspectives potentially capable to improve our understanding on the functions of these amino acids in pollen development, pollination, and pollen tube guidance. PMID:26388884

  8. Bark thickness across the angiosperms: more than just fire.

    Science.gov (United States)

    Rosell, Julieta A

    2016-07-01

    Global variation in total bark thickness (TBT) is traditionally attributed to fire. However, bark is multifunctional, as reflected by its inner living and outer dead regions, meaning that, in addition to fire protection, other factors probably contribute to TBT variation. To address how fire, climate, and plant size contribute to variation in TBT, inner bark thickness (IBT) and outer bark thickness (OBT), I sampled 640 species spanning all major angiosperm clades and 18 sites with contrasting precipitation, temperature, and fire regime. Stem size was by far the main driver of variation in thickness, with environment being less important. IBT was closely correlated with stem diameter, probably for metabolic reasons, and, controlling for size, was thicker in drier and hotter environments, even fire-free ones, probably reflecting its water and photosynthate storage role. OBT was less closely correlated with size, and was thicker in drier, seasonal sites experiencing frequent fires. IBT and OBT covaried loosely and both contributed to overall TBT variation. Thickness variation was higher within than across sites and was evolutionarily labile. Given high within-site diversity and the multiple selective factors acting on TBT, continued study of the different drivers of variation in bark thickness is crucial to understand bark ecology. PMID:26890029

  9. Einstein Revisited

    Science.gov (United States)

    Fine, Leonard

    2005-01-01

    A brief description on the work and life of the great physicist scientist Albert Einstein is presented. The photoelectric paper written by him in 1905 led him to the study of fluctuations in the energy density of radiation and from there to the incomplete nature of the equipartition theorem of classical mechanics, which failed to account for…

  10. Utility of the Amborella trichopoda expansin superfamily in elucidating the history of angiosperm expansins.

    Science.gov (United States)

    Seader, Victoria H; Thornsberry, Jennifer M; Carey, Robert E

    2016-03-01

    Expansins form a superfamily of plant proteins that assist in cell wall loosening during growth and development. The superfamily is divided into four families: EXPA, EXPB, EXLA, and EXLB (Sampedro and Cosgrove in Genome Biol 6:242, 2005. doi: 10.1186/gb-2005-6-12-242 ). Previous studies on Arabidopsis, rice, and Populus trichocarpa have clarified the evolutionary history of expansins in angiosperms (Sampedro et al. in Plant J 44:409-419, 2005. doi: 10.1111/j.1365-313X.2005.02540.x ). Amborella trichopoda is a flowering plant that diverged very early. Thus, it is a sister lineage to all other extant angiosperms (Amborella Genome Project in 342:1241089, 2013. doi: 10.1126/science.1241089 ). Because of this relationship, comparing the A. trichopoda expansin superfamily with those of other flowering plants may indicate which expansin genes were present in the last common ancestor of all angiosperms. The A. trichopoda expansin superfamily was assembled using BLAST searches with angiosperm expansin queries. The search results were analyzed and annotated to isolate the complete A. trichopoda expansin superfamily. This superfamily is similar to other angiosperm expansin superfamilies, but is somewhat smaller. This is likely because of a lack of genome duplication events (Amborella Genome Project 2013). Phylogenetic and syntenic analyses of A. trichopoda expansins have improved our understanding of the evolutionary history of expansins in angiosperms. Nearly all of the A. trichopoda expansins were placed into an existing Arabidopsis-rice expansin clade. Based on the results of phylogenetic and syntenic analyses, we estimate there were 12-13 EXPA genes, 2 EXPB genes, 1 EXLA gene, and 2 EXLB genes in the last common ancestor of all angiosperms. PMID:26646380

  11. Leukemia revisited

    International Nuclear Information System (INIS)

    Selected features of the historical development of our knowledge of leukemia are discussed. The use of different methodologies for study of the nature of leukemic cell proliferation are analyzed. The differences between older cell kinetic data using tritiated thymidine and autoradiography and the newer cell culture methods are more apparent than real. It is suggested that tritiated thymidine and extracorporeal irradiation of the blood may be useful for therapeutic agents that have not been given an adequate trial. Radiation leukemogenesis presents an opportunity for study of the nature of leukemogenesis that has not been exploited adequately

  12. Leukemia revisited

    Energy Technology Data Exchange (ETDEWEB)

    Cronkite, E P

    1980-01-01

    Selected features of the historical development of our knowledge of leukemia are discussed. The use of different methodologies for study of the nature of leukemic cell proliferation are analyzed. The differences between older cell kinetic data using tritiated thymidine and autoradiography and the newer cell culture methods are more apparent than real. It is suggested that tritiated thymidine and extracorporeal irradiation of the blood may be useful for therapeutic agents that have not been given an adequate trial. Radiation leukemogenesis presents an opportunity for study of the nature of leukemogenesis that has not been exploited adequately.

  13. Chernobyl revisited

    International Nuclear Information System (INIS)

    Observations made on a visit to the Chernobyl area in July 1990 are reported. Although the main purpose of the visit was to try out thermoluminescence techniques on materials exposed to radiation during the accident, the observations reported here are of a more general nature covering the variations in dose rate and contamination of surfaces within the 30 km exclusion zone and in the deserted tow of Pripyat, and plant, animal and bird life. The most ubiquitous contamination in Pripyat is caesium, which has penetrated all porous surfaces and would probably be very difficult to remove from brick structures if rehabitation were ever contemplated. Recorded dose-rates varied considerably on and in different parts of buildings. Radiation measurements of external surfaces were typically in the range 1-10 μSv/h and an order of magnitude less within buildings. Grass verges were particularly badly contaminated; measurements up to 110 μSv/h were noted in the most polluted area of Pripyat. Ecologically, the area seems to have benefited from having been allowed to return to nature. Many birds and a wide variety of plants and trees were flourishing; some older pine trees showed evidence of damage, however. The only insects observed were peacock butterflies. (Author)

  14. Ecological determinants of mean family age of angiosperm trees in forest communities in China

    Science.gov (United States)

    Qian, Hong; Chen, Shengbin

    2016-01-01

    Species assemblage in a local community is determined by the interplay of evolutionary and ecological processes. The Tropical Niche Conservatism hypothesis proposes mechanisms underlying patterns of biodiversity in biological communities along environmental gradients. This hypothesis predicts that, among other things, clades in areas with warm or wet environments are, on average, older than those in areas with cold or dry environments. Focusing on angiosperm trees in forests, this study tested the age-related prediction of the Tropical Niche Conservatism hypothesis. We related the mean family age of angiosperm trees in 57 local forests from across China with 23 current and paleo-environmental variables, which included all major temperature- and precipitation-related variables. Our study shows that the mean family age of angiosperm trees in local forests was positively correlated with temperature and precipitation. This finding is consistent with the age-related prediction of the Tropical Niche Conservatism hypothesis. Approximately 85% of the variance in the mean family age of angiosperm trees was explained by temperature-related variables, and 81% of the variance in the mean family age of angiosperm trees was explained by precipitation-related variables. Climatic conditions at the Last Glacial Maximum did not explain additional variation in mean family age after accounting for current environmental conditions. PMID:27354109

  15. Oxidative phosphorylation revisited

    DEFF Research Database (Denmark)

    Nath, Sunil; Villadsen, John

    2015-01-01

    The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic explan...

  16. Darwin's second 'abominable mystery': Why are there so many angiosperm species?

    Science.gov (United States)

    Crepet, William L; Niklas, Karl J

    2009-01-01

    The rapid diversification and ecological dominance of the flowering plants beg the question "Why are there so many angiosperm species and why are they so successful?" A number of equally plausible hypotheses have been advanced in response to this question, among which the most widely accepted highlights the mutually beneficial animal-plant relationships that are nowhere better developed nor more widespread than among angiosperm species and their biotic vectors for pollination and dispersal. Nevertheless, consensus acknowledges that there are many other attributes unique to or characteristic of the flowering plants. In addition, the remarkable coevolution of the angiosperms and pollination/dispersal animal agents could be an effect of the intrinsic adaptability of the flowering plants rather than a primary cause of their success, suggesting that the search for underlying causes should focus on an exploration of the genetic and epigenetic mechanisms that might facilitate adaptive evolution and speciation. Here, we explore angiosperm diversity promoting attributes in their general form and draw particular attention to those that, either individually or collectively, have been shown empirically to favor high speciation rates, low extinction rates, or broad ecological tolerances. Among these are the annual growth form, homeotic gene effects, asexual/sexual reproduction, a propensity for hybrid polyploidy, and apparent "resistance" to extinction. Our survey of the literature suggests that no single vegetative, reproductive, or ecological feature taken in isolation can account for the evolutionary success of the angiosperms. Rather, we believe that the answer to Darwin's second "abominable mystery" lies in a confluence of features that collectively make the angiosperms unique among the land plants. PMID:21628194

  17. Unequal plastid distribution during the development of the male gametophyte of angiosperms

    Directory of Open Access Journals (Sweden)

    R. Hagemann

    2014-02-01

    Full Text Available The difference between the uniparental maternal and biparental type of plastid inheritance is based upon a relatively simple mechanism. In the uniparental type plastids are excluded from the generative or siperm cells during the firts pollen mitosis or during pollen development. In some angiosperms this exclusion is completely lacking or carried out partially.

  18. Effects of plant diversity on primary production and species interactions in brackish water angiosperm communities

    DEFF Research Database (Denmark)

    Salo, Tiina; Gustafsson, Camilla; Boström, Christoffer

    2009-01-01

    plant productivity in brackish water angiosperm communities, a 14 wk field experiment was conducted. Using a replacement design with a standardized initial aboveground biomass, shoots of Zostera marina, Potamogeton filiformis and P. perfoliatus were planted on a shallow, sandy bottom in replicated...

  19. Did homeodomain proteins duplicate before the origin of angiosperms, fungi, and metazoa?

    Science.gov (United States)

    Bharathan, G; Janssen, B J; Kellogg, E A; Sinha, N

    1997-12-01

    Homeodomain proteins are transcription factors that play a critical role in early development in eukaryotes. These proteins previously have been classified into numerous subgroups whose phylogenetic relationships are unclear. Our phylogenetic analysis of representative eukaryotic sequences suggests that there are two major groups of homeodomain proteins, each containing sequences from angiosperms, metazoa, and fungi. This result, based on parsimony and neighbor-joining analyses of primary amino acid sequences, was supported by two additional features of the proteins. The two protein groups are distinguished by an insertion/deletion in the homeodomain, between helices I and II. In addition, an amphipathic alpha-helical secondary structure in the region N terminal of the homeodomain is shared by angiosperm and metazoan sequences in one group. These results support the hypothesis that there was at least one duplication of homeobox genes before the origin of angiosperms, fungi, and metazoa. This duplication, in turn, suggests that these proteins had diverse functions early in the evolution of eukaryotes. The shared secondary structure in angiosperm and metazoan sequences points to an ancient conserved functional domain. PMID:9391098

  20. Did homeodomain proteins duplicate before the origin of angiosperms, fungi, and metazoa?

    Science.gov (United States)

    Bharathan, Geeta; Janssen, Bart-Jan; Kellogg, Elizabeth A.; Sinha, Neelima

    1997-01-01

    Homeodomain proteins are transcription factors that play a critical role in early development in eukaryotes. These proteins previously have been classified into numerous subgroups whose phylogenetic relationships are unclear. Our phylogenetic analysis of representative eukaryotic sequences suggests that there are two major groups of homeodomain proteins, each containing sequences from angiosperms, metazoa, and fungi. This result, based on parsimony and neighbor-joining analyses of primary amino acid sequences, was supported by two additional features of the proteins. The two protein groups are distinguished by an insertion/deletion in the homeodomain, between helices I and II. In addition, an amphipathic alpha-helical secondary structure in the region N terminal of the homeodomain is shared by angiosperm and metazoan sequences in one group. These results support the hypothesis that there was at least one duplication of homeobox genes before the origin of angiosperms, fungi, and metazoa. This duplication, in turn, suggests that these proteins had diverse functions early in the evolution of eukaryotes. The shared secondary structure in angiosperm and metazoan sequences points to an ancient conserved functional domain. PMID:9391098

  1. Ontogenetic shifts in plant-plant interactions in a rare cycad within angiosperm communities.

    Science.gov (United States)

    Álvarez-Yépiz, Juan C; Búrquez, Alberto; Dovčiak, Martin

    2014-06-01

    Gymnosperms and angiosperms can co-occur within the same habitats but key plant traits are thought to give angiosperms an evolutionary competitive advantage in many ecological settings. We studied ontogenetic changes in competitive and facilitative interactions between a rare gymnosperm (Dioon sonorense, our target species) and different plant and abiotic neighbours (conspecific-cycads, heterospecific-angiosperms, or abiotic-rocks) from 2007 to 2010 in an arid environment of northwestern Mexico. We monitored survival and growth of seedlings, juveniles, and adults of the cycad Dioon sonorense to evaluate how cycad survival and relative height growth rate (RHGR) responded to intra- and interspecific competition, canopy openness, and nearest neighbour. We tested spatial associations among D. sonorense life stages and angiosperm species and measured ontogenetic shifts in cycad shade tolerance. Canopy openness decreased cycad survival while intraspecific competition decreased survival and RHGR during early ontogeny. Seedling survival was higher in association with rocks and heterospecific neighbours where intraspecific competition was lower. Shade tolerance decreased with cycad ontogeny reflecting the spatial association of advanced stages with more open canopies. Interspecific facilitation during early ontogeny of our target species may promote its persistence in spite of increasing interspecific competition in later stages. We provide empirical support to the long-standing assumption that marginal rocky habitats serve as refugia from angiosperm competition for slow-growing gymnosperms such as cycads. The lack of knowledge of plant-plant interactions in rare or endangered species may hinder developing efficient conservation strategies (e.g. managing for sustained canopy cover), especially under the ongoing land use and climatic changes. PMID:24652529

  2. Diversification rates and chromosome evolution in the most diverse angiosperm genus of the temperate zone (Carex, Cyperaceae).

    Science.gov (United States)

    Escudero, Marcial; Hipp, Andrew L; Waterway, Marcia J; Valente, Luis M

    2012-06-01

    The sedge family (Cyperaceae: Poales; ca. 5600 spp.) is a hyperdiverse cosmopolitan group with centres of species diversity in Africa, Australia, eastern Asia, North America, and the Neotropics. Carex, with ca. 40% of the species in the family, is one of the most species-rich angiosperm genera and the most diverse in temperate regions of the Northern Hemisphere, making it atypical among plants in that it inverts the latitudinal gradient of species richness. Moreover, Carex exhibits high rates of chromosome rearrangement via fission, fusion, and translocation, which distinguishes it from the rest of the Cyperaceae. Here, we use a phylogenetic framework to examine how the onset of contemporary temperate climates and the processes of chromosome evolution have influenced the diversification dynamics of Carex. We provide estimates of diversification rates and map chromosome transitions across the evolutionary history of the main four clades of Carex. We demonstrate that Carex underwent a shift in diversification rates sometime between the Late Eocene and the Oligocene, during a global cooling period, which fits with a transition in diploid chromosome number. We suggest that adaptive radiation to novel temperate climates, aided by a shift in the mode of chromosome evolution, may explain the large-scale radiation of Carex and its latitudinal pattern of species richness. PMID:22366369

  3. High precision mass measurements in Ψ and Υ families revisited

    International Nuclear Information System (INIS)

    High precision mass measurements in Ψ and Υ families performed in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited. The corrections for the new value of the electron mass are presented. The effect of the updated radiative corrections has been calculated for the J/Ψ(1S) and Ψ(2S) mass measurements

  4. Barcoding success as a function of phylogenetic relatedness in Viburnum, a clade of woody angiosperms

    Directory of Open Access Journals (Sweden)

    Clement Wendy L

    2012-05-01

    Full Text Available Abstract Background The chloroplast genes matK and rbcL have been proposed as a “core” DNA barcode for identifying plant species. Published estimates of successful species identification using these loci (70-80% may be inflated because they may have involved comparisons among distantly related species within target genera. To assess the ability of the proposed two-locus barcode to discriminate closely related species, we carried out a hierarchically structured set of comparisons within Viburnum, a clade of woody angiosperms containing ca. 170 species (some 70 of which are currently used in horticulture. For 112 Viburnum species, we evaluated rbcL + matK, as well as the chloroplast regions rpl32-trnL, trnH-psbA, trnK, and the nuclear ribosomal internal transcribed spacer region (nrITS. Results At most, rbcL + matK could discriminate 53% of all Viburnum species, with only 18% of the comparisons having genetic distances >1%. When comparisons were progressively restricted to species within major Viburnum subclades, there was a significant decrease in both the discriminatory power and the genetic distances. trnH-psbA and nrITS show much higher levels of variation and potential discriminatory power, and their use in plant barcoding should be reconsidered. As barcoding has often been used to discriminate species within local areas, we also compared Viburnum species within two regions, Japan and Mexico and Central America. Greater success in discriminating among the Japanese species reflects the deeper evolutionary history of Viburnum in that area, as compared to the recent radiation of a single clade into the mountains of Latin America. Conclusions We found very low levels of discrimination among closely related species of Viburnum, and low levels of variation in the proposed barcoding loci may limit success within other clades of long-lived woody plants. Inclusion of the supplementary barcodes trnH-psbA and nrITS increased discrimination rates but

  5. Exploring Early Angiosperm Fire Feedbacks using Coupled Experiments and Modelling Approaches to Estimate Cretaceous Palaeofire Behaviour

    Science.gov (United States)

    Belcher, Claire; Hudpsith, Victoria

    2016-04-01

    Using the fossil record we are typically limited to exploring linkages between palaeoecological changes and palaeofire activity by assessing the abundance of charcoals preserved in sediments. However, it is the behaviour of fires that primarily governs their ecological effects. Therefore, the ability to estimate variations in aspects of palaeofire behaviour such as palaeofire intensity and rate of spread would be of key benefit toward understanding the coupled evolutionary history of ecosystems and fire. The Cretaceous Period saw major diversification in land plants. Previously, conifers (gymnosperms) and ferns (pteridophytes) dominated Earth's ecosystems until flowering plants (angiosperms) appear in the fossil record of the Early Cretaceous (~135Ma). We have created surface fire behaviour estimates for a variety of angiosperm invasion scenarios and explored the influence of Cretaceous superambient atmospheric oxygen levels on the fire behaviour occurring in these new Cretaceous ecosystems. These estimates are then used to explore the hypothesis that the early spread of the angiosperms was promoted by the novel fire regimes that they created. In order to achieve this we tested the flammability of Mesozoic analogue fuel types in controlled laboratory experiments using an iCone calorimeter, which measured the ignitability as well as the effective heat of combustion of the fuels. We then used the BehavePlus fire behaviour modelling system to scale up our laboratory results to the ecosystem scale. Our results suggest that fire-angiosperm feedbacks may have occurred in two phases: The first phase being a result of weedy angiosperms providing an additional easily ignitable fuel that enhanced both the seasonality and frequency of surface fires. In the second phase, the addition of shrubby understory fuels likely expanded the number of ecosystems experiencing more intense surface fires, resulting in enhanced mortality and suppressed post-fire recruitment of gymnosperms

  6. The Faraday effect revisited

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, Gheorghe

    2009-01-01

    This paper is the second in a series revisiting the (effect of) Faraday rotation. We formulate and prove the thermodynamic limit for the transverse electric conductivity of Bloch electrons, as well as for the Verdet constant. The main mathematical tool is a regularized magnetic and geometric...

  7. Colloquial Hebrew Imperatives Revisited

    Science.gov (United States)

    Bolozky, Shmuel

    2009-01-01

    In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

  8. Deterministic Graphical Games Revisited

    DEFF Research Database (Denmark)

    Andersson, Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro; Sørensen, Troels Bjerre

    2008-01-01

    We revisit the deterministic graphical games of Washburn. A deterministic graphical game can be described as a simple stochastic game (a notion due to Anne Condon), except that we allow arbitrary real payoffs but disallow moves of chance. We study the complexity of solving deterministic graphical...

  9. Life quality index revisited

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2004-01-01

    The derivation of the life quality index (LQI) is revisited for a revision. This revision takes into account the unpaid but necessary work time needed to stay alive in clean and healthy conditions to be fit for effective wealth producing work and to enjoyable free time. Dimension analysis...

  10. The Linguistic Repertoire Revisited

    Science.gov (United States)

    Busch, Brigitta

    2012-01-01

    This article argues for the relevance of poststructuralist approaches to the notion of a linguistic repertoire and introduces the notion of language portraits as a basis for empirical study of the way in which speakers conceive and represent their heteroglossic repertoires. The first part of the article revisits Gumperz's notion of a linguistic…

  11. Comparative chloroplast genomics: Analyses including new sequencesfrom the angiosperms Nuphar advena and Ranunculus macranthus

    Energy Technology Data Exchange (ETDEWEB)

    Raubeso, Linda A.; Peery, Rhiannon; Chumley, Timothy W.; Dziubek,Chris; Fourcade, H. Matthew; Boore, Jeffrey L.; Jansen, Robert K.

    2007-03-01

    The number of completely sequenced plastid genomes available is growing rapidly. This new array of sequences presents new opportunities to perform comparative analyses. In comparative studies, it is most useful to compare across wide phylogenetic spans and, within angiosperms, to include representatives from basally diverging lineages such as the new genomes reported here: Nuphar advena (from a basal-most lineage) and Ranunculus macranthus (from the basal group of eudicots). We report these two new plastid genome sequences and make comparisons (within angiosperms, seed plants, or all photosynthetic lineages) to evaluate features such as the status of ycf15 and ycf68 as protein coding genes, the distribution of simple sequence repeats (SSRs) and longer dispersed repeats (SDR), and patterns of nucleotide composition.

  12. Testing the recent theories for the origin of the hermaphrodite flower by comparison of the transcriptomes of gymnosperms and angiosperms

    Directory of Open Access Journals (Sweden)

    Tavares Raquel

    2010-08-01

    Full Text Available Abstract Background Different theories for the origin of the angiosperm hermaphrodite flower make different predictions concerning the overlap between the genes expressed in the male and female cones of gymnosperms and the genes expressed in the hermaphrodite flower of angiosperms. The Mostly Male (MM theory predicts that, of genes expressed primarily in male versus female gymnosperm cones, an excess of male orthologs will be expressed in flowers, excluding ovules, while Out Of Male (OOM and Out Of Female (OOF theories predict no such excess. Results In this paper, we tested these predictions by comparing the transcriptomes of three gymnosperms (Ginkgo biloba, Welwitschia mirabilis and Zamia fisheri and two angiosperms (Arabidopsis thaliana and Oryza sativa, using EST data. We found that the proportion of orthologous genes expressed in the reproductive organs of the gymnosperms and in the angiosperms flower is significantly higher than the proportion of orthologous genes expressed in the reproductive organs of the gymnosperms and in the angiosperms vegetative tissues, which shows that the approach is correct. However, we detected no significant differences between the proportion of gymnosperm orthologous genes expressed in the male cone and in the angiosperms flower and the proportion of gymnosperm orthologous genes expressed in the female cone and in the angiosperms flower. Conclusions These results do not support the MM theory prediction of an excess of male gymnosperm genes expressed in the hermaphrodite flower of the angiosperms and seem to support the OOM/OOF theories. However, other explanations can be given for the 1:1 ratio that we found. More abundant and more specific (namely carpel and ovule expression data should be produced in order to further test these theories.

  13. Preferential fertilization in Plumbago: Ultrastructural evidence for gamete-level recognition in an angiosperm

    OpenAIRE

    Russell, Scott D.

    1985-01-01

    Gametic fusion patterns in the angiosperm Plumbago zeylanica were determined by using cytoplasmically dimorphic sperm cells differing in mitochondrion and plastid content and then identifying paternal organelles through their ultrastructural characteristics within the maternal cytoplasm at the time of fertilization. The virtual absence of plastids within the sperm cell that is physically associated with the vegetative nucleus allows paternal plastids to be used to trace the fate of the two ma...

  14. CenH3 evolution in diploids and polyploids of three angiosperm genera

    OpenAIRE

    Masonbrink, Rick E.; Gallagher, Joseph P.; Jareczek, Josef J; Renny-Byfield, Simon; Grover, Corrinne E.; Gong, Lei; Wendel, Jonathan F.

    2014-01-01

    Background Centromeric DNA sequences alone are neither necessary nor sufficient for centromere specification. The centromere specific histone, CenH3, evolves rapidly in many species, perhaps as a coevolutionary response to rapidly evolving centromeric DNA. To gain insight into CenH3 evolution, we characterized patterns of nucleotide and protein diversity among diploids and allopolyploids within three diverse angiosperm genera, Brassica, Oryza, and Gossypium (cotton), with a focus on evidence ...

  15. Did homeodomain proteins duplicate before the origin of angiosperms, fungi, and metazoa?

    OpenAIRE

    Bharathan, Geeta; Janssen, Bart-Jan; Kellogg, Elizabeth A.; Sinha, Neelima

    1997-01-01

    Homeodomain proteins are transcription factors that play a critical role in early development in eukaryotes. These proteins previously have been classified into numerous subgroups whose phylogenetic relationships are unclear. Our phylogenetic analysis of representative eukaryotic sequences suggests that there are two major groups of homeodomain proteins, each containing sequences from angiosperms, metazoa, and fungi. This result, based on parsimony and neighbor-joining analyses of primary ami...

  16. Oil biosynthesis in a basal angiosperm: transcriptome analysis of Persea Americana mesocarp

    OpenAIRE

    Kilaru, Aruna; Cao, Xia; Dabbs, Parker B.; Sung, Ha-Jung; Rahman, Md. Mahbubur; Thrower, Nicholas; Zynda, Greg; Podicheti, Ram; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Mockaitis, Keithanne; Ohlrogge, John B.

    2015-01-01

    Background The mechanism by which plants synthesize and store high amounts of triacylglycerols (TAG) in tissues other than seeds is not well understood. The comprehension of controls for carbon partitioning and oil accumulation in nonseed tissues is essential to generate oil-rich biomass in perennial bioenergy crops. Persea americana (avocado), a basal angiosperm with unique features that are ancestral to most flowering plants, stores ~ 70 % TAG per dry weight in its mesocarp, a nonseed tissu...

  17. A Targeted Enrichment Strategy for Massively Parallel Sequencing of Angiosperm Plastid Genomes

    Directory of Open Access Journals (Sweden)

    Gregory W. Stull

    2013-02-01

    Full Text Available Premise of the study: We explored a targeted enrichment strategy to facilitate rapid and low-cost next-generation sequencing (NGS of numerous complete plastid genomes from across the phylogenetic breadth of angiosperms. Methods and Results: A custom RNA probe set including the complete sequences of 22 previously sequenced eudicot plastomes was designed to facilitate hybridization-based targeted enrichment of eudicot plastid genomes. Using this probe set and an Agilent SureSelect targeted enrichment kit, we conducted an enrichment experiment including 24 angiosperms (22 eudicots, two monocots, which were subsequently sequenced on a single lane of the Illumina GAIIx with single-end, 100-bp reads. This approach yielded nearly complete to complete plastid genomes with exceptionally high coverage (mean coverage: 717×, even for the two monocots. Conclusions: Our enrichment experiment was highly successful even though many aspects of the capture process employed were suboptimal. Hence, significant improvements to this methodology are feasible. With this general approach and probe set, it should be possible to sequence more than 300 essentially complete plastid genomes in a single Illumina GAIIx lane (achieving 50× mean coverage. However, given the complications of pooling numerous samples for multiplex sequencing and the limited number of barcodes (e.g., 96 available in commercial kits, we recommend 96 samples as a current practical maximum for multiplex plastome sequencing. This high-throughput approach should facilitate large-scale plastid genome sequencing at any level of phylogenetic diversity in angiosperms.

  18. Divergence of RNA polymerase α subunits in angiosperm plastid genomes is mediated by genomic rearrangement

    Science.gov (United States)

    Blazier, J. Chris; Ruhlman, Tracey A.; Weng, Mao-Lun; Rehman, Sumaiyah K.; Sabir, Jamal S. M.; Jansen, Robert K.

    2016-01-01

    Genes for the plastid-encoded RNA polymerase (PEP) persist in the plastid genomes of all photosynthetic angiosperms. However, three unrelated lineages (Annonaceae, Passifloraceae and Geraniaceae) have been identified with unusually divergent open reading frames (ORFs) in the conserved region of rpoA, the gene encoding the PEP α subunit. We used sequence-based approaches to evaluate whether these genes retain function. Both gene sequences and complete plastid genome sequences were assembled and analyzed from each of the three angiosperm families. Multiple lines of evidence indicated that the rpoA sequences are likely functional despite retaining as low as 30% nucleotide sequence identity with rpoA genes from outgroups in the same angiosperm order. The ratio of non-synonymous to synonymous substitutions indicated that these genes are under purifying selection, and bioinformatic prediction of conserved domains indicated that functional domains are preserved. One of the lineages (Pelargonium, Geraniaceae) contains species with multiple rpoA-like ORFs that show evidence of ongoing inter-paralog gene conversion. The plastid genomes containing these divergent rpoA genes have experienced extensive structural rearrangement, including large expansions of the inverted repeat. We propose that illegitimate recombination, not positive selection, has driven the divergence of rpoA. PMID:27087667

  19. Neutralino Dark Matter from Indirect Detection Revisited

    CERN Document Server

    Grajek, Phill; Phalen, Daniel J; Pierce, Aaron; Watson, Scott

    2008-01-01

    We revisit indirect detection possibilities for neutralino dark matter, emphasizing the complementary roles of different approaches. While thermally produced dark matter often requires large astrophysical "boost factors" to observe antimatter signals, the physically motivated alternative of non-thermal dark matter can naturally provide interesting signals, for example from light wino or Higgsino dark matter. After a brief review of cosmic ray propagation, we discuss signals for positrons, antiprotons, synchrotron radiation and gamma rays from wino annihilation in the galactic halo, and examine their phenomenology. For pure wino dark matter relevant to the LHC, PAMELA and GLAST should report signals.

  20. Radiation

    International Nuclear Information System (INIS)

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  1. The SLEEPER genes: a transposase-derived angiosperm-specific gene family

    Directory of Open Access Journals (Sweden)

    Knip Marijn

    2012-10-01

    Full Text Available Abstract Background DAYSLEEPER encodes a domesticated transposase from the hAT-superfamily, which is essential for development in Arabidopsis thaliana. Little is known about the presence of DAYSLEEPER orthologs in other species, or how and when it was domesticated. We studied the presence of DAYSLEEPER orthologs in plants and propose a model for the domestication of the ancestral DAYSLEEPER gene in angiosperms. Results Using specific BLAST searches in genomic and EST libraries, we found that DAYSLEEPER-like genes (hereafter called SLEEPER genes are unique to angiosperms. Basal angiosperms as well as grasses (Poaceae and dicotyledonous plants possess such putative orthologous genes, but SLEEPER-family genes were not found in gymnosperms, mosses and algae. Most species contain more than one SLEEPER gene. All SLEEPERs contain a C2H2 type BED-zinc finger domain and a hATC dimerization domain. We designated 3 motifs, partly overlapping the BED-zinc finger and dimerization domain, which are hallmark features in the SLEEPER family. Although SLEEPER genes are structurally conserved between species, constructs with SLEEPER genes from grapevine and rice did not complement the daysleeper phenotype in Arabidopsis, when expressed under control of the DAYSLEEPER promoter. However these constructs did cause a dominant phenotype when expressed in Arabidopsis. Rice plant lines with an insertion in the RICESLEEPER1 or 2 locus displayed phenotypic abnormalities, indicating that these genes are functional and important for normal development in rice. We suggest a model in which we hypothesize that an ancestral hAT transposase was retrocopied and stably integrated in the genome during early angiosperm evolution. Evidence is also presented for more recent retroposition events of SLEEPER genes, such as an event in the rice genome, which gave rise to the RICESLEEPER1 and 2 genes. Conclusions We propose the ancestral SLEEPER gene was formed after a process of retro

  2. "The Theory of Heat Radiation" Revisited: A Commentary on the Validity of Kirchhoff's Law of Thermal Emission and Max Planck's Claim of Universality

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2015-04-01

    Full Text Available Affirming Kirchhoff’s Law of thermal emission, Max Planck conferred upon his own equation and its constants, h and k , universal significance. All arbitrary cavities were said to behave as blackbodies. They were thought to contain b lack, or normal radiation, which depended only upon temperature and frequency of observation, irrespective of the nature of the cavity walls. Today, laboratory blackbodies a re specialized, heated devices whose interior walls are lined with highly absorptive surfaces, such as graphite, soot, or other sophisticated materials. Such evidence repeatedly calls into question Kirchhoff’s Law, as nothing in the laboratory is independent of the nature of the walls. By focusing on Max Planck’s classic text, “ The Theory of Heat Radiation ’, it can be demonstrated that the German physicist was unable to properly justify Kirchhoff’s Law. At every turn, he was confronted with the fact that materials possess frequency dependent reflectivity and absorptivity, but he often chose to sidestep these realities. He used polarized light to derive Kirchhoff’s Law, when it is well known that blackbody radiation is never polar- ized. Through the use of an element, d σ , at the bounding surface between two media, he reached the untenable position that arbitrary materials have the same reflective prop- erties. His Eq.40 ( ρ = ρ ′ , constituted a dismissal of experimental reality. It is evident that if one neglects reflection, then all cavities must be black. Unable to ensure that perfectly reflecting cavities can be filled with black radiation, Planck inserted a minute carbon particle, which he qualified as a “catalyst”. In fact, it was acting as a perfect absorber, fully able to provide, on its own, the radiation sought. In 1858, Balfour Stew- art had outlined that the proper treatment of cavity radiation must include reflection. Yet, Max Planck did not cite the Scottish scientist. He also d id not correctly address

  3. Fossil turbulence revisited

    CERN Document Server

    Gibson, C H

    1999-01-01

    A theory of fossil turbulence presented in the 11th Liege Colloquium on Marine turbulence is "revisited" in the 29th Liege Colloquium "Marine Turbulence Revisited". The Gibson (1980) theory applied universal similarity theories of turbulence and turbulent mixing to the vertical evolution of an isolated patch of turbulence in a stratified fluid as it is constrained and fossilized by buoyancy forces. Towed oceanic microstructure measurements of Schedvin (1979) confirmed the predicted universal constants. Universal constants, spectra, hydrodynamic phase diagrams (HPDs) and other predictions of the theory have been reconfirmed by a wide variety of field and laboratory observations. Fossil turbulence theory has many applications; for example, in marine biology, laboratory and field measurements suggest phytoplankton species with different swimming abilities adjust their growth strategies differently by pattern recognition of several days of turbulence-fossil-turbulence dissipation and persistence times above thres...

  4. The bar instability revisited

    OpenAIRE

    Chiodi, Filippo; Andreotti, Bruno; Claudin, Philippe

    2012-01-01

    The river bar instability is revisited, using a hydrodynamical model based on Reynolds averaged Navier-Stokes equations. The results are contrasted with the standard analysis based on shallow water Saint-Venant equations. We first show that the stability of both transverse modes (ripples) and of small wavelength inclined modes (bars) predicted by the Saint-Venant approach are artefacts of this hydrodynamical approximation. When using a more reliable hydrodynamical model, the dispersion relati...

  5. Reverse cholesterol transport revisited

    Institute of Scientific and Technical Information of China (English)

    Astrid; E; van; der; Velde

    2010-01-01

    Reverse cholesterol transport was originally described as the high-density lipoprotein-mediated cholesterol flux from the periphery via the hepatobiliary tract to the intestinal lumen, leading to fecal excretion. Since the introduction of reverse cholesterol transport in the 1970s, this pathway has been intensively investigated. In this topic highlight, the classical reverse cholesterol transport concepts are discussed and the subject reverse cholesterol transport is revisited.

  6. Divergent expression patterns of miR164 and CUP-SHAPED COTYLEDON genes in palms and other monocots: implication for the evolution of meristem function in angiosperms.

    Science.gov (United States)

    Adam, Hélène; Marguerettaz, Mélanie; Qadri, Rashad; Adroher, Bernard; Richaud, Frédérique; Collin, Myriam; Thuillet, Anne-Céline; Vigouroux, Yves; Laufs, Patrick; Tregear, James W; Jouannic, Stefan

    2011-04-01

    In order to understand how the morphology of plant species has diversified over time, it is necessary to decipher how the underlying developmental programs have evolved. The regulatory network controlling shoot meristem activity is likely to have played an important role in morphological diversification and useful insights can be gained by comparing monocots and eudicots. These two distinct monophyletic groups of angiosperms diverged 130 Ma and are characterized by important differences in their morphology. Several studies of eudicot species have revealed a conserved role for NAM and CUC3 genes in meristem functioning and pattern formation through the definition of morphogenetic boundaries during development. In this study, we show that NAM- and CUC3-related genes are conserved in palms and grasses, their diversification having predated the radiation of monocots and eudicots. Moreover, the NAM-miR164 posttranscriptional regulatory module is also conserved in palm species. However, in contrast to the CUC3-related genes, which share a similar expression pattern between the two angiosperm groups, the expression domain of the NAM-miR164 module differs between monocot and eudicot species. In our studies of spatial expression patterns, we compared existing eudicot data with novel results from our work using two palm species (date palm and oil palm) and two members of the Poaceae (rice and millet). In addition to contrasting results obtained at the gene expression level, major differences were also observed between eudicot and monocot NAM-related genes in the occurrence of putative cis-regulatory elements in their promoter sequences. Overall, our results suggest that although NAM- and CUC3-related proteins are functionally equivalent between monocots and eudicots, evolutionary radiation has resulted in heterotopy through alterations in the expression domain of the NAM-miR164 regulatory module. PMID:21135149

  7. The world's high background natural radiation areas (HBNRAs) revisited: A broad overview of the dosimetric, epidemiological and radiobiological issues

    International Nuclear Information System (INIS)

    The residents of the world's high background natural radiation areas (HBNRAs), such as Ramsar (in Iran), Guarapari (in Brazil), Orissa and Kerala (in India) and Yangjiang (in China) have lived in these areas for generations under extraordinary radiation fields. The failure of earlier epidemiological studies to report any substantial increase in cancer incidence in HBNRAs has raised some controversy regarding the validity of the linear no-threshold hypothesis. This paper reviews some of the most recent studies of HBNRAs with the intent of stimulating greater research interest in the dosimetric, epidemiological and radiobiological issues related to the world's HBNRAs and proposes solutions to the challenges facing HBNRA studies. This paper may serve as a useful reference for some of the harder-to-find literature. - Highlights: • Some of the challenging issues of HBNRAs have not been resolved. • A literature review of the most recent studies of HBNRAs has been conducted. • An overview of some of the challenging issues and viable solutions are presented

  8. Analogue Magnetism Revisited

    CERN Document Server

    Osano, Bob

    2016-01-01

    In this article we revisit the significance of the often debated structural similarity between the equations of electromagnetism and fluid dynamics. Although the matching of the two sets of equations has successfully been done for non-dissipative forms of the equations, little has been done for cases where the dissipative terms are non-negligible. We consider the consequence of non-negligible viscosity and diffusivity, and how the fine-tuning of these parameters could allow fluid dynamics to be used to indirectly study certain properties of magnetic fields.

  9. Bottomonium spectrum revisited

    Science.gov (United States)

    Segovia, Jorge; Ortega, Pablo G.; Entem, David R.; Fernández, Francisco

    2016-04-01

    We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector, and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about a better way to determine their properties experimentally.

  10. T-duality revisited

    OpenAIRE

    Erik Plauschinn

    2014-01-01

    We revisit the transformation rules of the metric and Kalb-Ramond field under T-duality, and express the corresponding relations in terms of the metric G and the field strength H = dB . In the course of the derivation, we find an explanation for potential reductions of the isometry group in the dual background. The formalism employed in this paper is illustrated with examples based on tori and spheres, where for the latter we construct a new non-geometric background.

  11. Deterministic Graphical Games Revisited

    DEFF Research Database (Denmark)

    Andersson, Klas Olof Daniel; Hansen, Kristoffer Arnsfelt; Miltersen, Peter Bro;

    2012-01-01

    as retrograde analysis, have been rediscovered independently. We then revisit Washburn’s deterministic graphical games (DGGs), a natural generalization of chess-like games to arbitrary zero-sum payoffs. We study the complexity of solving DGGs and obtain an almost-linear time comparison......Starting from Zermelo’s classical formal treatment of chess, we trace through history the analysis of two-player win/lose/draw games with perfect information and potentially infinite play. Such chess-like games have appeared in many different research communities, and methods for solving them, such...

  12. Reframing in dentistry: revisited.

    Science.gov (United States)

    Nuvvula, Sivakumar; Kamatham, Rekalakshmi; Challa, Ramasubbareddy; Asokan, Sharath

    2013-01-01

    The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child's behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice. PMID:24021326

  13. Evolutionary dynamics of microsatellite distribution in plants: insight from the comparison of sequenced brassica, Arabidopsis and other angiosperm species.

    Directory of Open Access Journals (Sweden)

    Jiaqin Shi

    Full Text Available Despite their ubiquity and functional importance, microsatellites have been largely ignored in comparative genomics, mostly due to the lack of genomic information. In the current study, microsatellite distribution was characterized and compared in the whole genomes and both the coding and non-coding DNA sequences of the sequenced Brassica, Arabidopsis and other angiosperm species to investigate their evolutionary dynamics in plants. The variation in the microsatellite frequencies of these angiosperm species was much smaller than those for their microsatellite numbers and genome sizes, suggesting that microsatellite frequency may be relatively stable in plants. The microsatellite frequencies of these angiosperm species were significantly negatively correlated with both their genome sizes and transposable elements contents. The pattern of microsatellite distribution may differ according to the different genomic regions (such as coding and non-coding sequences. The observed differences in many important microsatellite characteristics (especially the distribution with respect to motif length, type and repeat number of these angiosperm species were generally accordant with their phylogenetic distance, which suggested that the evolutionary dynamics of microsatellite distribution may be generally consistent with plant divergence/evolution. Importantly, by comparing these microsatellite characteristics (especially the distribution with respect to motif type the angiosperm species (aside from a few species all clustered into two obviously different groups that were largely represented by monocots and dicots, suggesting a complex and generally dichotomous evolutionary pattern of microsatellite distribution in angiosperms. Polyploidy may lead to a slight increase in microsatellite frequency in the coding sequences and a significant decrease in microsatellite frequency in the whole genome/non-coding sequences, but have little effect on the microsatellite

  14. The complete chloroplast genome sequence of Ampelopsis: gene organization, comparative analysis and phylogenetic relationships to other angiosperms

    Directory of Open Access Journals (Sweden)

    Gurusamy eRaman

    2016-03-01

    Full Text Available Ampelopsis brevipedunculata is an economically important plant that belongs to the Vitaceae family of angiosperms. The phylogenetic placement of Vitaceae is still unresolved. Recent phylogenetic studies suggested that it should be placed in various alternative families including Caryophyllaceae, asteraceae, Saxifragaceae, Dilleniaceae, or with the rest of the rosid families. However, these analyses provided weak supportive results because they were based on only one of several genes. Accordingly, complete chloroplast genome sequences are required to resolve the phylogenetic relationships among angiosperms. Recent phylogenetic analyses based on the complete chloroplast genome sequence suggested strong support for the position of Vitaceae as the earliest diverging lineage of rosids and placed it as a sister to the remaining rosids. These studies also revealed relationships among several major lineages of angiosperms; however, they highlighted the significance of taxon sampling for obtaining accurate phylogenies. In the present study, we sequenced the complete chloroplast genome of A. brevipedunculata and used these data to assess the relationships among 32 angiosperms, including 18 taxa of rosids. The Ampelopsis chloroplast genome is 161,090 bp in length, and includes a pair of inverted repeats of 26,394 bp that are separated by small and large single copy regions of 19,036 bp and 89,266 bp, respectively. The gene content and order of Ampelopsis is identical to many other unrearranged angiosperm chloroplast genomes, including Vitis and tobacco. A phylogenetic tree constructed based on 70 protein-coding genes of 33 angiosperms showed that both Saxifragales and Vitaceae diverged from the rosid clade and formed two clades with 100% bootstrap value. The position of the Vitaceae is sister to Saxifragales, and both are the basal and earliest diverging lineages. Moreover, Saxifragales forms a sister clade to Vitaceae of rosids. Overall, the results of

  15. Mitochondrial DNA suggests at least 11 origins of parasitism in angiosperms and reveals genomic chimerism in parasitic plants

    Directory of Open Access Journals (Sweden)

    Croom Henrietta B

    2007-12-01

    Full Text Available Abstract Background Some of the most difficult phylogenetic questions in evolutionary biology involve identification of the free-living relatives of parasitic organisms, particularly those of parasitic flowering plants. Consequently, the number of origins of parasitism and the phylogenetic distribution of the heterotrophic lifestyle among angiosperm lineages is unclear. Results Here we report the results of a phylogenetic analysis of 102 species of seed plants designed to infer the position of all haustorial parasitic angiosperm lineages using three mitochondrial genes: atp1, coxI, and matR. Overall, the mtDNA phylogeny agrees with independent studies in terms of non-parasitic plant relationships and reveals at least 11 independent origins of parasitism in angiosperms, eight of which consist entirely of holoparasitic species that lack photosynthetic ability. From these results, it can be inferred that modern-day parasites have disproportionately evolved in certain lineages and that the endoparasitic habit has arisen by convergence in four clades. In addition, reduced taxon, single gene analyses revealed multiple horizontal transfers of atp1 from host to parasite lineage, suggesting that parasites may be important vectors of horizontal gene transfer in angiosperms. Furthermore, in Pilostyles we show evidence for a recent host-to-parasite atp1 transfer based on a chimeric gene sequence that indicates multiple historical xenologous gene acquisitions have occurred in this endoparasite. Finally, the phylogenetic relationships inferred for parasites indicate that the origins of parasitism in angiosperms are strongly correlated with horizontal acquisitions of the invasive coxI group I intron. Conclusion Collectively, these results indicate that the parasitic lifestyle has arisen repeatedly in angiosperm evolutionary history and results in increasing parasite genomic chimerism over time.

  16. The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea

    KAUST Repository

    Olsen, Jeanine L.

    2016-01-27

    Seagrasses colonized the sea1 on at least three independent occasions to form the basis of one of the most productive and widespread coastal ecosystems on the planet2. Here we report the genome of Zostera marina (L.), the first, to our knowledge, marine angiosperm to be fully sequenced. This reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes3, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing. Seagrasses have also regained functions enabling them to adjust to full salinity. Their cell walls contain all of the polysaccharides typical of land plants, but also contain polyanionic, low-methylated pectins and sulfated galactans, a feature shared with the cell walls of all macroalgae4 and that is important for ion homoeostasis, nutrient uptake and O2/CO2 exchange through leaf epidermal cells. The Z. marina genome resource will markedly advance a wide range of functional ecological studies from adaptation of marine ecosystems under climate warming5, 6, to unravelling the mechanisms of osmoregulation under high salinities that may further inform our understanding of the evolution of salt tolerance in crop plants7.

  17. Mechanisms for independent cytoplasmic inheritance of mitochondria and plastids in angiosperms.

    Science.gov (United States)

    Nagata, Noriko

    2010-03-01

    The inheritance of mitochondria and plastids in angiosperms has been categorized into three modes:maternal, biparental and paternal. Many mechanisms have been proposed for maternal inheritance, including: (1) physical exclusion of the organelle itself during pollenmitosis I (PMI); (2) elimination of the organelle by formation of enucleated cytoplasmic bodies (ECB); (3) autophagic degradation of organelles during male gametophyte development; (4) digestion of the organelle after fertilization; and (5)--the most likely possibility--digestion of organellar DNA in generative cells just after PMI. In detailed cytological observations, the presence or absence of mitochondrial and plastid DNA in generative cells corresponds to biparental/paternal inheritance or maternal inheritance of the respective organelle examined genetically. These improved cytological observations demonstrate that the replication or digestion of organellar DNA in young generative cells just after PMI is a critical point determining the mode of cytoplasmic inheritance. This review describes the independent control mechanisms in mitochondria and plastids that lead to differences in cytoplasmic inheritance in angiosperms. PMID:20196234

  18. Genome size and ploidy influence angiosperm species' biomass under nitrogen and phosphorus limitation.

    Science.gov (United States)

    Guignard, Maïté S; Nichols, Richard A; Knell, Robert J; Macdonald, Andy; Romila, Catalina-Andreea; Trimmer, Mark; Leitch, Ilia J; Leitch, Andrew R

    2016-06-01

    Angiosperm genome sizes (GS) range c. 2400-fold, and as nucleic acids are amongst the most phosphorus- (P) and nitrogen (N)-demanding cellular biomolecules, we test the hypothesis that a key influence on plant biomass and species composition is the interaction between N and P availability and plant GS. We analysed the impact of different nutrient regimes on above-ground biomass of angiosperm species with different GS, ploidy level and Grime's C-S-R (competitive, stress-tolerant, ruderal) plant strategies growing at the Park Grass Experiment (Rothamsted, UK), established in 1856. The biomass-weighted mean GS of species growing on plots with the addition of both N and P fertilizer were significantly higher than that of plants growing on control plots and plots with either N or P. The plants on these N + P plots are dominated by polyploids with large GS and a competitive plant strategy. The results are consistent with our hypothesis that large genomes are costly to build and maintain under N and P limitation. Hence GS and ploidy are significant traits affecting biomass growth under different nutrient regimes, influencing plant community composition and ecosystem dynamics. We propose that GS is a critical factor needed in models that bridge the knowledge gap between biodiversity and ecosystem functioning. PMID:26875784

  19. The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea.

    Science.gov (United States)

    Olsen, Jeanine L; Rouzé, Pierre; Verhelst, Bram; Lin, Yao-Cheng; Bayer, Till; Collen, Jonas; Dattolo, Emanuela; De Paoli, Emanuele; Dittami, Simon; Maumus, Florian; Michel, Gurvan; Kersting, Anna; Lauritano, Chiara; Lohaus, Rolf; Töpel, Mats; Tonon, Thierry; Vanneste, Kevin; Amirebrahimi, Mojgan; Brakel, Janina; Boström, Christoffer; Chovatia, Mansi; Grimwood, Jane; Jenkins, Jerry W; Jueterbock, Alexander; Mraz, Amy; Stam, Wytze T; Tice, Hope; Bornberg-Bauer, Erich; Green, Pamela J; Pearson, Gareth A; Procaccini, Gabriele; Duarte, Carlos M; Schmutz, Jeremy; Reusch, Thorsten B H; Van de Peer, Yves

    2016-02-18

    Seagrasses colonized the sea on at least three independent occasions to form the basis of one of the most productive and widespread coastal ecosystems on the planet. Here we report the genome of Zostera marina (L.), the first, to our knowledge, marine angiosperm to be fully sequenced. This reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing. Seagrasses have also regained functions enabling them to adjust to full salinity. Their cell walls contain all of the polysaccharides typical of land plants, but also contain polyanionic, low-methylated pectins and sulfated galactans, a feature shared with the cell walls of all macroalgae and that is important for ion homoeostasis, nutrient uptake and O2/CO2 exchange through leaf epidermal cells. The Z. marina genome resource will markedly advance a wide range of functional ecological studies from adaptation of marine ecosystems under climate warming, to unravelling the mechanisms of osmoregulation under high salinities that may further inform our understanding of the evolution of salt tolerance in crop plants. PMID:26814964

  20. The bar instability revisited

    CERN Document Server

    Chiodi, Filippo; Claudin, Philippe

    2012-01-01

    The river bar instability is revisited, using a hydrodynamical model based on Reynolds averaged Navier-Stokes equations. The results are contrasted with the standard analysis based on shallow water Saint-Venant equations. We first show that the stability of both transverse modes (ripples) and of small wavelength inclined modes (bars) predicted by the Saint-Venant approach are artefacts of this hydrodynamical approximation. When using a more reliable hydrodynamical model, the dispersion relation does not present any maximum of the growth rate when the sediment transport is assumed to be locally saturated. The analysis therefore reveals the fundamental importance of the relaxation of sediment transport towards equilibrium as it it is responsible for the stabilisation of small wavelength modes. This dynamical mechanism is characterised by the saturation number, defined as the ratio of the saturation length to the water depth Lsat/H. This dimensionless number controls the transition from ripples (transverse patte...

  1. Quantum duel revisited

    International Nuclear Information System (INIS)

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α1 and α2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent. (paper)

  2. Firewall Configuration Errors Revisited

    CERN Document Server

    Wool, Avishai

    2009-01-01

    The first quantitative evaluation of the quality of corporate firewall configurations appeared in 2004, based on Check Point FireWall-1 rule-sets. In general that survey indicated that corporate firewalls were often enforcing poorly written rule-sets, containing many mistakes. The goal of this work is to revisit the first survey. The current study is much larger. Moreover, for the first time, the study includes configurations from two major vendors. The study also introduce a novel "Firewall Complexity" (FC) measure, that applies to both types of firewalls. The findings of the current study indeed validate the 2004 study's main observations: firewalls are (still) poorly configured, and a rule-set's complexity is (still) positively correlated with the number of detected risk items. Thus we can conclude that, for well-configured firewalls, ``small is (still) beautiful''. However, unlike the 2004 study, we see no significant indication that later software versions have fewer errors (for both vendors).

  3. Logistics Innovation Process Revisited

    DEFF Research Database (Denmark)

    Gammelgaard, Britta; Su, Shong-Iee Ivan; Yang, Su-Lan

    2011-01-01

    Purpose – The purpose of this paper is to learn more about logistics innovation processes and their implications for the focal organization as well as the supply chain, especially suppliers. Design/methodology/approach – The empirical basis of the study is a longitudinal action research project...... that was triggered by the practical needs of new ways of handling material flows of a hospital. This approach made it possible to revisit theory on logistics innovation process. Findings – Apart from the tangible benefits reported to the case hospital, five findings can be extracted from this study: the logistics...... innovation process model may include not just customers but also suppliers; logistics innovation in buyer-supplier relations may serve as an alternative to outsourcing; logistics innovation processes are dynamic and may improve supplier partnerships; logistics innovations in the supply chain are as dependent...

  4. Reframing in dentistry: Revisited

    Directory of Open Access Journals (Sweden)

    Sivakumar Nuvvula

    2013-01-01

    Full Text Available The successful practice of dentistry involves a good combination of technical skills and soft skills. Soft skills or communication skills are not taught extensively in dental schools and it can be challenging to learn and at times in treating dental patients. Guiding the child′s behavior in the dental operatory is one of the preliminary steps to be taken by the pediatric dentist and one who can successfully modify the behavior can definitely pave the way for a life time comprehensive oral care. This article is an attempt to revisit a simple behavior guidance technique, reframing and explain the possible psychological perspectives behind it for better use in the clinical practice.

  5. Klein's double discontinuity revisited

    DEFF Research Database (Denmark)

    Winsløw, Carl; Grønbæk, Niels

    2014-01-01

    bridging measures, success rates and many other aspects of these “entrance transition” problems. In this paper, we consider the inverse transition, experienced by university students as they revisit core parts of high school mathematics (in particular, calculus) after completing the undergraduate......Much effort and research has been invested into understanding and bridging the ‘gaps’ which many students experience in terms of contents and expectations as they begin university studies with a heavy component of mathematics, typically in the form of calculus courses. We have several studies of...... mathematics courses which are mandatory to become a high school teacher of mathematics. To what extent does the “advanced” experience enable them to approach the high school calculus in a deeper and more autonomous way ? To what extent can “capstone” courses support such an approach ? How could it be hindered...

  6. Quantum duel revisited

    Science.gov (United States)

    Schmidt, Alexandre G. M.; Paiva, Milena M.

    2012-03-01

    We revisit the quantum two-person duel. In this problem, both Alice and Bob each possess a spin-1/2 particle which models dead and alive states for each player. We review the Abbott and Flitney result—now considering non-zero α1 and α2 in order to decide if it is better for Alice to shoot or not the second time—and we also consider a duel where players do not necessarily start alive. This simple assumption allows us to explore several interesting special cases, namely how a dead player can win the duel shooting just once, or how can Bob revive Alice after one shot, and the better strategy for Alice—being either alive or in a superposition of alive and dead states—fighting a dead opponent.

  7. Lorentz violation naturalness revisited

    CERN Document Server

    Belenchia, Alessio; Liberati, Stefano

    2016-01-01

    We revisit here the naturalness problem of Lorentz invariance violations on a simple toy model of a scalar field coupled to a fermion field via a Yukawa interaction. We first review some well-known results concerning the low-energy percolation of Lorentz violation from high energies, presenting some details of the analysis not explicitly discussed in the literature and discussing some previously unnoticed subtleties. We then show how a separation between the scale of validity of the effective field theory and that one of Lorentz invariance violations can hinder this low-energy percolation. While such protection mechanism was previously considered in the literature, we provide here a simple illustration of how it works and of its general features. Finally, we consider a case in which dissipation is present, showing that the dissipative behaviour does not percolate generically to lower mass dimension operators albeit dispersion does. Moreover, we show that a scale separation can protect from unsuppressed low-en...

  8. Evolution of Xylan Substitution Patterns in Gymnosperms and Angiosperms: Implications for Xylan Interaction with Cellulose.

    Science.gov (United States)

    Busse-Wicher, Marta; Li, An; Silveira, Rodrigo L; Pereira, Caroline S; Tryfona, Theodora; Gomes, Thiago C F; Skaf, Munir S; Dupree, Paul

    2016-08-01

    The interaction between cellulose and xylan is important for the load-bearing secondary cell wall of flowering plants. Based on the precise, evenly spaced pattern of acetyl and glucuronosyl (MeGlcA) xylan substitutions in eudicots, we recently proposed that an unsubstituted face of xylan in a 2-fold helical screw can hydrogen bond to the hydrophilic surfaces of cellulose microfibrils. In gymnosperm cell walls, any role for xylan is unclear, and glucomannan is thought to be the important cellulose-binding polysaccharide. Here, we analyzed xylan from the secondary cell walls of the four gymnosperm lineages (Conifer, Gingko, Cycad, and Gnetophyta). Conifer, Gingko, and Cycad xylan lacks acetylation but is modified by arabinose and MeGlcA. Interestingly, the arabinosyl substitutions are located two xylosyl residues from MeGlcA, which is itself placed precisely on every sixth xylosyl residue. Notably, the Gnetophyta xylan is more akin to early-branching angiosperms and eudicot xylan, lacking arabinose but possessing acetylation on alternate xylosyl residues. All these precise substitution patterns are compatible with gymnosperm xylan binding to hydrophilic surfaces of cellulose. Molecular dynamics simulations support the stable binding of 2-fold screw conifer xylan to the hydrophilic face of cellulose microfibrils. Moreover, the binding of multiple xylan chains to adjacent planes of the cellulose fibril stabilizes the interaction further. Our results show that the type of xylan substitution varies, but an even pattern of xylan substitution is maintained among vascular plants. This suggests that 2-fold screw xylan binds hydrophilic faces of cellulose in eudicots, early-branching angiosperm, and gymnosperm cell walls. PMID:27325663

  9. Multinomial pattern matching revisited

    Science.gov (United States)

    Horvath, Matthew S.; Rigling, Brian D.

    2015-05-01

    Multinomial pattern matching (MPM) is an automatic target recognition algorithm developed for specifically radar data at Sandia National Laboratories. The algorithm is in a family of algorithms that first quantizes pixel value into Nq bins based on pixel amplitude before training and classification. This quantization step reduces the sensitivity of algorithm performance to absolute intensity variation in the data, typical of radar data where signatures exhibit high variation for even small changes in aspect angle. Our previous work has focused on performance analysis of peaky template matching, a special case of MPM where binary quantization is used (Nq = 2). Unfortunately references on these algorithms are generally difficult to locate and here we revisit the MPM algorithm and illustrate the underlying statistical model and decision rules for two algorithm interpretations: the 1-of-K vector form and the scalar. MPM can also be used as a detector and specific attention is given to algorithm tuning where "peak pixels" are chosen based on their underlying empirical probabilities according to a reward minimization strategy aimed at reducing false alarms in the detection scenario and false positives in a classification capacity. The algorithms are demonstrated using Monte Carlo simulations on the AFRL civilian vehicle dataset for variety of choices of Nq.

  10. Revisiting energy efficiency fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lombard, L.; Velazquez, D. [Grupo de Termotecnia, Escuela Superior de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092 Seville (Spain); Ortiz, J. [Building Research Establishment (BRE), Garston, Watford, WD25 9XX (United Kingdom)

    2013-05-15

    Energy efficiency is a central target for energy policy and a keystone to mitigate climate change and to achieve a sustainable development. Although great efforts have been carried out during the last four decades to investigate the issue, focusing into measuring energy efficiency, understanding its trends and impacts on energy consumption and to design effective energy efficiency policies, many energy efficiency-related concepts, some methodological problems for the construction of energy efficiency indicators (EEI) and even some of the energy efficiency potential gains are often ignored or misunderstood, causing no little confusion and controversy not only for laymen but even for specialists. This paper aims to revisit, analyse and discuss some efficiency fundamental topics that could improve understanding and critical judgement of efficiency stakeholders and that could help in avoiding unfounded judgements and misleading statements. Firstly, we address the problem of measuring energy efficiency both in qualitative and quantitative terms. Secondly, main methodological problems standing in the way of the construction of EEI are discussed, and a sequence of actions is proposed to tackle them in an ordered fashion. Finally, two key topics are discussed in detail: the links between energy efficiency and energy savings, and the border between energy efficiency improvement and renewable sources promotion.

  11. Radiation

    International Nuclear Information System (INIS)

    The basic facts about radiation are explained, along with some simple and natural ways of combating its ill-effects, based on ancient healing wisdom as well as the latest biochemical and technological research. Details are also given of the diet that saved thousands of lives in Nagasaki after the Atomic bomb attack. Special comment is made on the use of radiation for food processing. (U.K.)

  12. Radiation

    International Nuclear Information System (INIS)

    Exposure to solar and ionizing radiation increases the risk for cancer in humans. Some 5% of solar radiation is within the ultraviolet spectrum and may cause both malignant melanoma and non-melanocytic skin cancer; the latter is regarded as a benign disease and is accordingly not included in our estimation of avoidable cancers. Under the assumption that the rate of occurrence of malignant melanoma of the buttocks of both men and women and of the scalp of women would apply to all parts of the body in people completely unexposed to solar radiation, it was estimated that approximately 95% of all malignant melanomas arising in the Nordic populations around the year 2000 will be due to exposure to natural ultraviolet radiation, equivalent to an annual number of about 4700 cases, with 2100 in men and 2600 in women, or some 4% of all cancers notified. Exposure to ionizing radiation in the Nordic countries occurs at an average effective dose per capita per year of about 3 mSv (Iceland, 1.1 mSv) from natural sources, and about 1 mSv from man-made sources. While the natural sources are primarily radon in indoor air, natural radionuclides in food, cosmic radiation and gamma radiation from soil and building materials, the man-made sources are dominated by the diagnostic and therapeutic use of ionizing radiation. On the basis of measured levels of radon in Nordic dwellings and associated risk estimates for lung cancer derived from well-conducted epidemiological studies, we estimated that about 180 cases of lung cancer (1% of all lung cancer cases) per year could be avoided in the Nordic countries around the year 2000 if indoor exposure to radon were eliminated, and that an additional 720 cases (6%) could be avoided annually if either radon or tobacco smoking were eliminated. Similarly, it was estimated that the exposure of the Nordic populations to natural sources of ionizing radiation other than radon and to medical sources will each give rise to an annual total of 2120

  13. Leadership and Management Theories Revisited

    DEFF Research Database (Denmark)

    Madsen, Mona Toft

    2001-01-01

    The goal of the paper is to revisit and analyze key contributions to the understanding of leadership and management. As a part of the discussion a role perspective that allows for additional and/or integrated leader dimensions, including a change-centered, will be outlined. Seemingly, a major...

  14. The "Mushroom Cloud" Demonstration Revisited

    Science.gov (United States)

    Panzarasa, Guido; Sparnacci, Katia

    2013-01-01

    A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

  15. Cultural Warping of Childbirth, Revisited

    OpenAIRE

    Budin, Wendy C.

    2007-01-01

    In this column, the editor of The Journal of Perinatal Education revisits Doris Haire's classic 1972 article, “The Cultural Warping of Childbirth,” and describes the birth culture of today. The editor also describes the contents of this issue, which offer a broad range of resources, research, and inspiration for childbirth educators in their efforts to promote normal birth.

  16. Recent Acceleration of Plastid Sequence and Structural Evolution Coincides with Extreme Mitochondrial Divergence in the Angiosperm Genus Silene

    OpenAIRE

    Sloan, Daniel B; Alverson, Andrew J; Wu, Martin; Palmer, Jeffrey D.; Taylor, Douglas R.

    2012-01-01

    The angiosperm genus Silene exhibits some of the most extreme and rapid divergence ever identified in mitochondrial genome architecture and nucleotide substitution rates. These patterns have been considered mitochondrial specific based on the absence of correlated changes in the small number of available nuclear and plastid gene sequences. To better assess the relationship between mitochondrial and plastid evolution, we sequenced the plastid genomes from four Silene species with fully sequenc...

  17. Modes of Gene Duplication Contribute Differently to Genetic Novelty and Redundancy, but Show Parallels across Divergent Angiosperms

    OpenAIRE

    Wang, Yupeng; Wang, Xiyin; Tang, Haibao; Tan, Xu; Ficklin, Stephen P.; Feltus, F. Alex; Andrew H. Paterson

    2011-01-01

    Background Both single gene and whole genome duplications (WGD) have recurred in angiosperm evolution. However, the evolutionary effects of different modes of gene duplication, especially regarding their contributions to genetic novelty or redundancy, have been inadequately explored. Results In Arabidopsis thaliana and Oryza sativa (rice), species that deeply sample botanical diversity and for which expression data are available from a wide range of tissues and physiological conditions, we ha...

  18. Insights into the dynamics of genome size and chromosome evolution in the early diverging angiosperm lineage Nymphaeales (water lilies).

    Science.gov (United States)

    Pellicer, J; Kelly, L J; Magdalena, C; Leitch, I J

    2013-08-01

    Nymphaeales are the most species-rich lineage of the earliest diverging angiosperms known as the ANA grade (Amborellales, Nymphaeales, Austrobaileyales), and they have received considerable attention from morphological, physiological, and ecological perspectives. Although phylogenetic relationships between these three lineages of angiosperms are mainly well resolved, insights at the whole genome level are still limited because of a dearth of information. To address this, genome sizes and chromosome numbers in 34 taxa, comprising 28 species were estimated and analysed together with previously published data to provide an overview of genome size and chromosome diversity in Nymphaeales. Overall, genome sizes were shown to vary 10-fold and chromosome numbers and ploidy levels ranged from 2n = 2x = 18 to 2n = 16x = ∼224. Distinct patterns of genome diversity were apparent, reflecting the differential incidence of polyploidy, changes in repetitive DNA content, and chromosome rearrangements within and between genera. Using model-based approaches, ancestral genome size and basic chromosome numbers were reconstructed to provide insights into the dynamics of genome size and chromosome number evolution. Finally, by combining additional data from Amborellales and Austrobaileyales, a comprehensive overview of genome sizes and chromosome numbers in these early diverging angiosperms is presented. PMID:24168627

  19. Internal habitat quality determines the effects of fragmentation on austral forest climbing and epiphytic angiosperms.

    Directory of Open Access Journals (Sweden)

    Ainhoa Magrach

    Full Text Available Habitat fragmentation has become one of the major threats to biodiversity worldwide, particularly in the case of forests, which have suffered enormous losses during the past decades. We analyzed how changes in patch configuration and habitat quality derived from the fragmentation of austral temperate rainforests affect the distribution of six species of forest-dwelling climbing and epiphytic angiosperms. Epiphyte and vine abundance is primarily affected by the internal characteristics of patches (such as tree size, the presence of logging gaps or the proximity to patch edges rather than patch and landscape features (such as patch size, shape or connectivity. These responses were intimately related to species-specific characteristics such as drought- or shade-tolerance. Our study therefore suggests that plant responses to fragmentation are contingent on both the species' ecology and the specific pathways through which the study area is being fragmented, (i.e. extensive logging that shaped the boundaries of current forest patches plus recent, unregulated logging that creates gaps within patches. Management practices in fragmented landscapes should therefore consider habitat quality within patches together with other spatial attributes at landscape or patch scales.

  20. Emerging roles for microtubules in angiosperm pollen tube growth highlight new research cues

    Directory of Open Access Journals (Sweden)

    Alessandra eMoscatelli

    2015-02-01

    Full Text Available In plants, actin filaments have an important role in organelle movement and cytoplasmic streaming. Otherwise microtubules have a role in restricting organelles to specific areas of the cell and in maintaining organelle morphology. In somatic plant cells, microtubules also participate in cell division and morphogenesis, allowing cells to take their definitive shape in order to perform specific functions. In the latter case, microtubules influence assembly of the cell wall, controlling the delivery of enzymes involved in cellulose synthesis and of wall modulation material to the proper sites.In angiosperm pollen tubes, organelle movement is generally attributed to the acto-myosin system, the main role of which is in distributing organelles in the cytoplasm and in carrying secretory vesicles to the apex for polarized growth. Recent data on membrane trafficking suggests a role of microtubules in fine delivery and repositioning of vesicles to sustain pollen tube growth. This review examines the role of microtubules in secretion and endocytosis, highlighting new research cues regarding cell wall construction and pollen tube-pistil crosstalk, that help unravel the role of microtubules in polarized growth.

  1. Coalescence vs. concatenation: Sophisticated analyses vs. first principles applied to rooting the angiosperms.

    Science.gov (United States)

    Simmons, Mark P; Gatesy, John

    2015-10-01

    It has recently been concluded that phylogenomic data from 310 nuclear genes support the clade of (Amborellales, Nymphaeales) as sister to the remaining angiosperms and that shortcut coalescent phylogenetic methods outperformed concatenation for these data. We falsify both of those conclusions here by demonstrating that discrepant results between the coalescent and concatenation analyses are primarily caused by the coalescent methods applied (MP-EST and STAR) not being robust to the highly divergent and often mis-rooted gene trees that were used. This result reinforces the expectation that low amounts of phylogenetic signal and methodological artifacts in gene-tree reconstruction can be more problematic for shortcut coalescent methods than is the assumption of a single hierarchy for all genes by concatenation methods when these approaches are applied to ancient divergences in empirical studies. We also demonstrate that a third coalescent method, ASTRAL, is more robust to mis-rooted gene trees than MP-EST or STAR, and that both Observed Variability (OV) and Tree Independent Generation of Evolutionary Rates (TIGER), which are two character subsampling procedures, are biased in favor of characters with highly asymmetrical distributions of character states when applied to this dataset. We conclude that enthusiastic application of novel tools is not a substitute for rigorous application of first principles, and that trending methods (e.g., shortcut coalescent methods applied to ancient divergences, tree-independent character subsampling), may be novel sources of previously under-appreciated, systematic errors. PMID:26002829

  2. Variation in ovule and seed size and associated size-number trade-offs in angiosperms.

    Science.gov (United States)

    Greenway, Carly A; Harder, Lawrence D

    2007-05-01

    Unlike pollen and seed size, the extent and causes of variation in ovule size remain unexplored. Based on 45 angiosperm species, we assessed whether intra- and interspecific variation in ovule size is consistent with cost minimization during ovule production or allows maternal plants to dominate conflict with their seeds concerning resource investment. Despite considerable intraspecific variation in ovule volume (mean CV = 0.356), ovule production by few species was subject to a size-number trade-off. Among the sampled species, ovule volume varied two orders of magnitude, whereas seed volume varied four orders of magnitude. Ovule volume varied positively among species with flower mass and negatively with ovule number. Tenuinucellate ovules were generally larger that crassinucellate ovules, and species with apical placentation (which mostly have uniovulate ovaries) had smaller ovules than those with other placentation types. Seed volume varied positively among species with fruit mass and seed development time, but negatively with seed number. Seeds grew a median 93-fold larger than the ovules from which they originated. Our results provide equivocal evidence that selection minimizes ovule size to allow efficient resource allocation after fertilization, but stronger evidence that ovule size affords maternal plants an advantage in parent-offspring conflict. PMID:21636453

  3. Floristic composition and community structure of epiphytic angiosperms in a terra firme forest in central Amazonia

    Directory of Open Access Journals (Sweden)

    Mariana Victória Irume

    2013-06-01

    Full Text Available This survey aimed to describe the floristic composition and structure of the epiphytic community occurring in a terra firme forest in the city of Coari, Brazil, in the Amazon region. Data collection was performed with a 1.5 ha plot method, with which upland, slope and lowland habitats were sampled. All angiosperm epiphytes and their host plants (diameter at breast height > 10 cm were sampled. We recorded 3.528 individuals in 13 families, 48 genera and 164 species. Araceae was the most prevalent family with regard to the importance value and stood out in all related parameters, followed by Bromeliaceae, Cyclanthaceae and Orchidaceae. The species with the highest epiphytic importance values were Guzmania lingulata (L. Mez. and Philodendron linnaei Kunth. The predominant life form was hemiepiphytic. Estimated floristic diversity was 3.2 (H'. The studied epiphytic community was distributed among 727 host plants belonging to 40 families, 123 genera and 324 species. One individual of Guarea convergens T.D. Penn. was the host with the highest richness and abundance of epiphytes. Stems/trunks of host plants were the most colonized segments, and the most favorable habitat for epiphytism was the lowlands, where 84.1% of species and 48.2% of epiphytic specimens were observed.

  4. General Botany of the Angiosperms in high school: a comparative analysis of textbooks

    Directory of Open Access Journals (Sweden)

    Lucas Cardoso Marinho

    2015-12-01

    Full Text Available Much of the textbooks content in Brazil is related to the historical period lived. With the advancement in the field of scientific research, the textbooks have become key pieces in the transfer/adaptation of this knowledge for the basic levels of education influencing positively or negatively in approach and presentation of content. The purpose of this study was to examine comparatively how the contents of General Botany of the Angiosperms are approached in three biology textbooks of high school (1974, 1999 and 2011. The 1974 book have long texts that include an elaborated discussion and there is a tendency to simplify the content. The book of the 1999 presents the content in the form of direct and specific concepts split into separate chapters. In this work, the reduced form compromises the discussion, giving up themes that enrich the study. The book of the 2011 separate the content into different chapters and keeps reducing the content but without losing the quality and clarity of their information. Over the years, from the best understanding of the textbooks objectives and scientific research involving these documents, it is clear that the most current book is more attractive and less dense, contributing of the deconstruct the idea of a boring and decorative Botany.

  5. The Hilbert monopole revisited

    OpenAIRE

    Sanz, Ivan; Anguera Pros, Jaume; Andújar Linares, Aurora; Puente Baliarda, Carles; Borja, C.

    2010-01-01

    A comparison between the resonant performance of the third iteration Hilbert monopole and a spiral shaped one of the same size and resonant frequency is presented. Quality factor, bandwidth, efficiency and radiation patterns are investigated. Although the Hilbert monopole total wire length is longer, it shows nearly the same radiation efficiency yet a lower quality factor. Hence the higher compression efficiency of the spiral shaped monopole does not provide any advantage in the antenna elect...

  6. Atmospheric predictability revisited

    Directory of Open Access Journals (Sweden)

    Lizzie S. R. Froude

    2013-06-01

    Full Text Available This article examines the potential to improve numerical weather prediction (NWP by estimating upper and lower bounds on predictability by re-visiting the original study of Lorenz (1982 but applied to the most recent version of the European Centre for Medium Range Weather Forecasts (ECMWF forecast system, for both the deterministic and ensemble prediction systems (EPS. These bounds are contrasted with an older version of the same NWP system to see how they have changed with improvements to the NWP system. The computations were performed for the earlier seasons of DJF 1985/1986 and JJA 1986 and the later seasons of DJF 2010/2011 and JJA 2011 using the 500-hPa geopotential height field. Results indicate that for this field, we may be approaching the limit of deterministic forecasting so that further improvements might only be obtained by improving the initial state. The results also show that predictability calculations with earlier versions of the model may overestimate potential forecast skill, which may be due to insufficient internal variability in the model and because recent versions of the model are more realistic in representing the true atmospheric evolution. The same methodology is applied to the EPS to calculate upper and lower bounds of predictability of the ensemble mean forecast in order to explore how ensemble forecasting could extend the limits of the deterministic forecast. The results show that there is a large potential to improve the ensemble predictions, but for the increased predictability of the ensemble mean, there will be a trade-off in information as the forecasts will become increasingly smoothed with time. From around the 10-d forecast time, the ensemble mean begins to converge towards climatology. Until this point, the ensemble mean is able to predict the main features of the large-scale flow accurately and with high consistency from one forecast cycle to the next. By the 15-d forecast time, the ensemble mean has lost

  7. Dynamic Topography Revisited

    Science.gov (United States)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The

  8. Remembered Experiences and Revisit Intentions

    DEFF Research Database (Denmark)

    Barnes, Stuart; Mattsson, Jan; Sørensen, Flemming

    2016-01-01

    Tourism is an experience-intensive sector in which customers seek and pay for experiences above everything else. Remembering past tourism experiences is also crucial for an understanding of the present, including the predicted behaviours of visitors to tourist destinations. We adopt a longitudinal...... approach to memory data collection from psychological science, which has the potential to contribute to our understanding of tourist behaviour. In this study, we examine the impact of remembered tourist experiences in a safari park. In particular, using matched survey data collected longitudinally and PLS...... path modelling, we examine the impact of positive affect tourist experiences on the development of revisit intentions. We find that longer-term remembered experiences have the strongest impact on revisit intentions, more so than predicted or immediate memory after an event. We also find that remembered...

  9. Two photosynthetic mechanisms mediating the low photorespiratory state in submersed aquatic angiosperms.

    Science.gov (United States)

    Salvucci, M E; Bowes, G

    1983-10-01

    The submersed angiosperms Myriophyllum spicatum L. and Hydrilla verticillata (L.f.) Royal exhibited different photosynthetic pulse-chase labeling patterns. In Hydrilla, over 50% of the (14)C was initially in malate and aspartate, but the fate of the malate depended upon the photorespiratory state of the plant. In low photorespiration Hydrilla, malate label decreased rapidly during an unlabeled chase, whereas labeling of sucrose and starch increased. In contrast, for high photorespiration Hydrilla, malate labeling continued to increase during a 2-hour chase. Thus, malate formation occurs in both photorespiratory states, but reduced photorespiration results when this malate is utilized in the light. Unlike Hydrilla, in low photorespiration Myriophyllum, (14)C incorporation was via the Calvin cycle, and less than 10% was in C(4) acids.Ethoxyzolamide, a carbonic anhydrase inhibitor and a repressor of the low photorespiratory state, increased the label in glycolate, glycine, and serine of Myriophyllum. Isonicotinic acid hydrazide increased glycine labeling of low photorespiration Myriophyllum from 14 to 25%, and from 12 to 48% with high photorespiration plants. Similar trends were observed with Hydrilla. Increasing O(2) increased the per cent [(14)C]glycine and the O(2) inhibition of photosynthesis in Myriophyllum. In low photorespiration Myriophyllum, glycine labeling and O(2) inhibition of photosynthesis were independent of the CO(2) level, but in high photorespiration plants the O(2) inhibition was competitively decreased by CO(2). Thus, in low but not high photorespiration plants, glycine labeling and O(2) inhibition appeared to be uncoupled from the external [O(2)]/[CO(2)] ratio.These data indicate that the low photorespiratory states of Hydrilla and Myriophyllum are mediated by different mechanisms, the former being C(4)-like, while the latter resembles that of low CO(2)-grown algae. Both may require carbonic anhydrase to enhance the use of inorganic carbon for

  10. Does multiple paternity affect seed mass in angiosperms? An experimental test in Dalechampia scandens.

    Science.gov (United States)

    Pélabon, C; Albertsen, E; Falahati-Anbaran, M; Wright, J; Armbruster, W S

    2015-09-01

    Flowers fertilized by multiple fathers may be expected to produce heavier seeds than those fertilized by a single father. However, the adaptive mechanisms leading to such differences remain unclear, and the evidence inconsistent. Here, we first review the different hypotheses predicting an increase in seed mass when multiple paternity occurs. We show that distinguishing between these hypotheses requires information about average seed mass, but also about within-fruit variance in seed mass, bias in siring success among pollen donors, and whether siring success and seed mass are correlated. We then report the results of an experiment on Dalechampia scandens (Euphorbiaceae), assessing these critical variables in conjunction with a comparison of seed mass resulting from crosses with single vs. multiple pollen donors. Siring success differed among males when competing for fertilization, but average seed mass was not affected by the number of fathers. Furthermore, paternal identity explained only 3.8% of the variance in seed mass, and siring success was not correlated with the mass of the seeds produced. Finally, within-infructescence variance in seed mass was not affected by the number of fathers. These results suggest that neither differential allocation nor sibling rivalry has any effect on the average mass of seeds in multiply sired fruits in D. scandens. Overall, the limited paternal effects observed in most studies and the possibility of diversification bet hedging among flowers (but not within flowers), suggest that multiple paternity within fruits or infructescence is unlikely to affect seed mass in a large number of angiosperm species. PMID:26174371

  11. A draft of the genome and four transcriptomes of a medicinal and pesticidal angiosperm Azadirachta indica

    Directory of Open Access Journals (Sweden)

    Krishnan Neeraja M

    2012-09-01

    Full Text Available Abstract Background The Azadirachta indica (neem tree is a source of a wide number of natural products, including the potent biopesticide azadirachtin. In spite of its widespread applications in agriculture and medicine, the molecular aspects of the biosynthesis of neem terpenoids remain largely unexplored. The current report describes the draft genome and four transcriptomes of A. indica and attempts to contextualise the sequence information in terms of its molecular phylogeny, transcript expression and terpenoid biosynthesis pathways. A. indica is the first member of the family Meliaceae to be sequenced using next generation sequencing approach. Results The genome and transcriptomes of A. indica were sequenced using multiple sequencing platforms and libraries. The A. indica genome is AT-rich, bears few repetitive DNA elements and comprises about 20,000 genes. The molecular phylogenetic analyses grouped A. indica together with Citrus sinensis from the Rutaceae family validating its conventional taxonomic classification. Comparative transcript expression analysis showed either exclusive or enhanced expression of known genes involved in neem terpenoid biosynthesis pathways compared to other sequenced angiosperms. Genome and transcriptome analyses in A. indica led to the identification of repeat elements, nucleotide composition and expression profiles of genes in various organs. Conclusions This study on A. indica genome and transcriptomes will provide a model for characterization of metabolic pathways involved in synthesis of bioactive compounds, comparative evolutionary studies among various Meliaceae family members and help annotate their genomes. A better understanding of molecular pathways involved in the azadirachtin synthesis in A. indica will pave ways for bulk production of environment friendly biopesticides.

  12. Revisiting Mutual Fund Performance Evaluation

    OpenAIRE

    Angelidis, Timotheos; Giamouridis, Daniel; Tessaromatis, Nikolaos

    2012-01-01

    Mutual fund manager excess performance should be measured relative to their self-reported benchmark rather than the return of a passive portfolio with the same risk characteristics. Ignoring the self-reported benchmark introduces biases in the measurement of stock selection and timing components of excess performance. We revisit baseline empirical evidence in mutual fund performance evaluation utilizing stock selection and timing measures that address these biases. We introduce a ...

  13. Markowitz Revisited: Social Portfolio Engineering

    OpenAIRE

    Gasser, Stephan; Kremser, Thomas; Rammerstorfer, Margarethe; Weinmayer, Karl

    2014-01-01

    In recent years socially responsible investing has become an increasingly more popular subject with both private and institutional investors. At the same time, a number of scientific papers have been published on socially responsible investments (SRIs), covering a broad range of topics, from what actually defines SRIs to the financial performance of SRI funds in contrast to non-SRI funds. In this paper, we revisit Markowitz' Portfolio Selection Theory and propose a modification...

  14. Leadership and Management Theories Revisited

    OpenAIRE

    Madsen, Mona Toft

    2001-01-01

    The goal of the paper is to revisit and analyze key contributions to the understanding of leadership and management. As a part of the discussion a role perspective that allows for additional and/or integrated leader dimensions, including a change-centered, will be outlined. Seemingly, a major challenge on the substantive level is the integration of soft and hard managerial functions, while the concepts used in presenting these should at least in transition be able to contain a distinction bet...

  15. Inference of phylogenetic relationships among key angiosperm lineages using a compatibility method on a molecular data set

    Institute of Scientific and Technical Information of China (English)

    Yin-Long QIU; George F.ESTABROOK

    2008-01-01

    Phylogenetic relationships among the five key angiosperm lineages,Ceratophyllum,Chloranthaceae,eudicots,magnoliids,and monocots,have resisted resolution despite several large-scale analyses sampling taxa and characters extensively and using various analytical methods.Meanwhile,compatibility methods,which were explored together with parsimony and likelihood methods during the early development stage of phylogenetics.have been greatly under-appreciated and not been used to analyze the massive amount of sequence data to reconstruct thye basal angiosperm phylogeny.In this study,we used a compatibility method on a data set of eight genes (mitochondrial atp1,matR,and nad5,plastid atpB,marK,rbcL,and rpoC2,and nuclear 18S rDNA)gathered in an earlier study.We selected two sets of characters that are compatible with more of the other characters than a random character would be with at probabilities of pM<0.1 and p<0.5 respectively.The resulting data matrices were subjected to parsimony and likelihood bootstrap analyses.Our unrooted parsimony analyses showed that Ceratophyllum was immediately related to eudicots,this larger lineage was immediately related to magnoliids,and monocots were closely related to Chloranthaceae.All these relationships received 76%-96% bootstrap support.A likelihood analysis of the 8 gene pM<0.5 compatible site matrix recovered the same topology but with low support.Likelihood analyses of other compatible site matrices produced different topologies that were all weakly supported.The topology reconstructed in the parsimony analyses agrees with the one recovered in the previous study using both parsimony and likelihood methods when no character was eliminated.Parts of this topology have also been recovered in several earlier studies.Hence,this topology plausibly reflects the true relationships among the five key angiosperm lineages.

  16. Koedam {beta} factors revisited

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J.E. [Physics Department, University of Wisconsin, Madison, WI (United States); Doughty, D.A. [Perkin-Elmer Optoelectronics, Santa Clara, CA (United States); Lister, G.G. [OSRAM SYLVANIA Inc., Beverly, MA (United States)

    2002-07-21

    A Koedam {beta} factor makes it possible to compute the total output power in line radiation from a positive column discharge using a single radiance measurement normal to an aperture in the wall. The results of analytic derivations of {beta} factors are presented for columns with uniform ({beta}=1.0) and parabolic ({beta}=0.75) excitation rates per unit volume and with negligible opacity. A Monte Carlo code for simulating radiation trapping with a spatially uniform density of absorbing atoms is then used to determine {beta} factors as a function of opacity. The code includes partial frequency redistribution and a Voigt line shape with radiative broadening, resonance collisional broadening, and Doppler broadening. The resulting {beta} factors are found to be nearly independent of opacity over a wide range of column radii for spectral line shapes dominated by Doppler broadening or by resonance collisional broadening. Additional Monte Carlo simulations are used to study {beta} factors as a function of a non-uniform density of absorbing atoms from radial cataphoresis with line shapes dominated by Doppler broadening, foreign gas broadening, and resonance collisional broadening. Radial cataphoresis is found to increase {beta} factors in all cases. Geometrical effects, refraction, and imperfect transmission at the glass wall are studied and found to decrease {beta} factors. (author)

  17. Koedam β factors revisited

    International Nuclear Information System (INIS)

    A Koedam β factor makes it possible to compute the total output power in line radiation from a positive column discharge using a single radiance measurement normal to an aperture in the wall. The results of analytic derivations of β factors are presented for columns with uniform (β=1.0) and parabolic (β=0.75) excitation rates per unit volume and with negligible opacity. A Monte Carlo code for simulating radiation trapping with a spatially uniform density of absorbing atoms is then used to determine β factors as a function of opacity. The code includes partial frequency redistribution and a Voigt line shape with radiative broadening, resonance collisional broadening, and Doppler broadening. The resulting β factors are found to be nearly independent of opacity over a wide range of column radii for spectral line shapes dominated by Doppler broadening or by resonance collisional broadening. Additional Monte Carlo simulations are used to study β factors as a function of a non-uniform density of absorbing atoms from radial cataphoresis with line shapes dominated by Doppler broadening, foreign gas broadening, and resonance collisional broadening. Radial cataphoresis is found to increase β factors in all cases. Geometrical effects, refraction, and imperfect transmission at the glass wall are studied and found to decrease β factors. (author)

  18. Revisiting the scattering greenhouse effect of CO2 ice clouds

    CERN Document Server

    Kitzmann, Daniel

    2016-01-01

    Carbon dioxide ice clouds are thought to play an important role for cold terrestrial planets with thick CO2 dominated atmospheres. Various previous studies showed that a scattering greenhouse effect by carbon dioxide ice clouds could result in a massive warming of the planetary surface. However, all of these studies only employed simplified two-stream radiative transfer schemes to describe the anisotropic scattering. Using accurate radiative transfer models with a general discrete ordinate method, this study revisits this important effect and shows that the positive climatic impact of carbon dioxide clouds was strongly overestimated in the past. The revised scattering greenhouse effect can have important implications for the early Mars, but also for planets like the early Earth or the position of the outer boundary of the habitable zone.

  19. Revisiting the Scattering Greenhouse Effect of CO2 Ice Clouds

    Science.gov (United States)

    Kitzmann, D.

    2016-02-01

    Carbon dioxide ice clouds are thought to play an important role for cold terrestrial planets with thick CO2 dominated atmospheres. Various previous studies showed that a scattering greenhouse effect by carbon dioxide ice clouds could result in a massive warming of the planetary surface. However, all of these studies only employed simplified two-stream radiative transfer schemes to describe the anisotropic scattering. Using accurate radiative transfer models with a general discrete ordinate method, this study revisits this important effect and shows that the positive climatic impact of carbon dioxide clouds was strongly overestimated in the past. The revised scattering greenhouse effect can have important implications for the early Mars, but also for planets like the early Earth or the position of the outer boundary of the habitable zone.

  20. Incentives for partitioning, revisited

    International Nuclear Information System (INIS)

    The incentives for separating and eliminating various elements from radioactive waste prior to final geologic disposal were investigated. Exposure pathways to humans were defined, and potential radiation doses to an individual living within the region of influence of the underground storage site were calculated. The assumed radionuclide source was 1/5 of the accumulated high-level waste from the US nuclear power economy through the year 2000. The repository containing the waste was assumed to be located in a reference salt site geology. The study required numerous assumptions concerning the transport of radioactivity from the geologic storage site to man. The assumptions used maximized the estimated potential radiation doses, particularly in the case of the intrusion water well scenario, where hydrologic flow field dispersion effects were ignored. Thus, incentives for removing elements from the waste tended to be maximized. Incentives were also maximized by assuming that elements removed from the waste could be eliminated from the earth without risk. The results of the study indicate that for reasonable disposal conditions, incentives for partitioning any elements from the waste in order to minimize the risk to humans are marginal at best

  1. MADS-box genes active in developing pollen cones of Norway spruce (Picea abies) are homologous to the B-class floral homeotic genes in angiosperms.

    Science.gov (United States)

    Sundström, J; Carlsbecker, A; Svensson, M E; Svenson, M; Johanson, U; Theissen, G; Engström, P

    1999-09-01

    The reproductive organs of conifers, the pollen cones and seed cones, differ in morphology from the angiosperm flower in several fundamental respects. In this report we present evidence to suggest that the two plant groups, in spite of these morphological differences and the long evolutionary distance between them, share important features in regulating the development of the reproductive organs. We present the cloning of three genes, DAL11, DAL12, and DAL13, from Norway spruce, all of which are related to the angiosperm B-class of homeotic genes. The B-class genes determine the identities of petals and stamens. They are members of a family of MADS-box genes, which also includes C-class genes that act to determine the identity of carpels and, in concert with B genes specify stamens in the angiosperm flower. Phylogenetic analyses and the presence of B-class specific C-terminal motifs in the DAL protein sequences imply homology to the B-class genes. Specific expression of all three genes in developing pollen cones suggests that the genes are involved in one aspect of B function, the regulation of development of the pollen-bearing organs. The different temporal and spatial expression patterns of the three DAL genes in the developing pollen cones indicate that the genes have attained at least in part distinct functions. The DAL11, DAL12, and 13 expression patterns in the pollen cone partly overlap with that of the previously identified DAL2 gene, which is structurally and functionally related to the angiosperm C-class genes. This result supports the hypothesis that an interaction between B- and C-type genes is required for male organ development in conifers like in the angiosperms. Taken together, our data suggests that central components in the regulatory mechanisms for reproductive organ development are conserved between conifers and angiosperms and, thus, among all seed plants. PMID:10528266

  2. Differential phylogenetic expansions in BAHD acyltransferases across five angiosperm taxa and evidence of divergent expression among Populus paralogues

    Directory of Open Access Journals (Sweden)

    Johnson Virgil E

    2011-05-01

    Full Text Available Abstract Background BAHD acyltransferases are involved in the synthesis and elaboration of a wide variety of secondary metabolites. Previous research has shown that characterized proteins from this family fall broadly into five major clades and contain two conserved protein motifs. Here, we aimed to expand the understanding of BAHD acyltransferase diversity in plants through genome-wide analysis across five angiosperm taxa. We focus particularly on Populus, a woody perennial known to produce an abundance of secondary metabolites. Results Phylogenetic analysis of putative BAHD acyltransferase sequences from Arabidopsis, Medicago, Oryza, Populus, and Vitis, along with previously characterized proteins, supported a refined grouping of eight major clades for this family. Taxon-specific clustering of many BAHD family members appears pervasive in angiosperms. We identified two new multi-clade motifs and numerous clade-specific motifs, several of which have been implicated in BAHD function by previous structural and mutagenesis research. Gene duplication and expression data for Populus-dominated subclades revealed that several paralogous BAHD members in this genus might have already undergone functional divergence. Conclusions Differential, taxon-specific BAHD family expansion via gene duplication could be an evolutionary process contributing to metabolic diversity across plant taxa. Gene expression divergence among some Populus paralogues highlights possible distinctions between their biochemical and physiological functions. The newly discovered motifs, especially the clade-specific motifs, should facilitate future functional study of substrate and donor specificity among BAHD enzymes.

  3. Neutron radiobiology revisited

    International Nuclear Information System (INIS)

    The present paper reviews the experimental results of normal tissue and tumour studies in animals. The dose per fraction dependence of the RBE in normal tissues has been long recognised, together with the steeper increase of RBE at low doses for late responding tissues compared with acute reactions. The dose dependence for tumours is more complex, because of hypoxia and reoxygenation, as well as differences in repair capability after high LET damage. A comparison of tumour and normal tissue RBE values shows that there is little experimental evidence for a therapeutic advantage at clinically relevant doses. In particular, the RBE for slow growing tumours is even lower than that for the faster growing mouse tumours. The reasons for the loss of expected neutron benefits in clinically relevant experiments are discussed. The disappointing prospects for neutrons are contrasted with the current multifactorial approaches to overcoming resistance to more conventional low LET radiations, including acceleration, hyperfractionation and several types of hypoxic cell radiosensitizers. (orig.)

  4. Des aliments tu feras medecine: Hippocrate revisite

    OpenAIRE

    Lahlou, Saadi

    1999-01-01

    "Let foods be your medicine Hippocrates revisited". In this article the author discusses the behaviour of consumers, concepts of 'health foods' and helth eating towards food and the rise of businesses built around the health food industry.

  5. Orthovoltage machines revisited

    International Nuclear Information System (INIS)

    Until the advent of megavoltage radiation, orthovoltage units operating up to 300 KV were used to deliver radiotherapy. Side effects due to higher doses to normal organs were inevitable because of less penetrating photon beams. With the advent of the megavoltage equipment more penetrating photon beams replaced the orthovoltage beams to treat deep seated tumours more effectively. The use of the orthovoltage energy range has since been limited to superficial skin cancers and many palliative treatments such as bony metastases, in particular ribs and spine. When the Linear Accelerators (linacs) with electron energy range were introduced into the radiotherapy field the use of orthovoltage range was further reduced. The electron beams were successfully used to treat superficial cancers and the demand for the orthovoltage units became less. Because of this many of the reputable manufacturers of orthovoltage units (eg. Philips) ceased the production of these units over a decade. During the eighties, the only available orthovoltage unit was the Siemens Stabilopan. In the early nineties Pantak introduced a new orthovoltage unit incorporated with new technology. NSW cancer treatment centres purchased several of these machines. Considering the capital cost and the annual maintenance cost, reliability, computer controlled accurate dose delivery, number of RT staff required to operate the unit and the Medicare revenue, it is cost beneficial to install an orthovoltage unit in a modern radiotherapy department. Copyright (1999) Australian Institute of Radiography

  6. The Phantom brane revisited

    Science.gov (United States)

    Sahni, Varun

    2016-07-01

    The Phantom brane is based on the normal branch of the DGP braneworld. It possesses a phantom-like equation of state at late times, but no big-rip future singularity. In this braneworld, the cosmological constant is dynamically screened at late times. Consequently it provides a good fit to SDSS DR11 measurements of H(z) at high redshifts. We obtain a closed system of equations for scalar perturbations on the brane. Perturbations of radiation, matter and the Weyl fluid are self-consistently evolved until the present epoch. We find that the late time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials φ, Ψ evolve differently on the brane than in ΛCDM, for which φ = Ψ. On the Brane, by contrast, the ratio φ/Ψ exceeds unity during the late matter dominated epoch (z ≤ 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large scale structure. The phantom brane also displays a pole in its equation of state, which provides a key test of this dark energy model.

  7. Photoevaporation of Circumstellar Disks Revisited: The Dust-Free Case

    CERN Document Server

    Tanaka, Kei E I; Omukai, Kazuyuki

    2013-01-01

    Photoevaporation by stellar ionizing radiation is believed to play an important role in the dispersal of disks around young stars. The mass loss model for dust-free disks developed by Hollenbach et al. is currently regarded as a conventional one and has been used in a wide variety of studies. However, the rate in this model was derived by the crude so-called 1+1D approximation of ionizing radiation transfer, which assumes that diffuse radiation propagates in a direction vertical to the disk. In this study, we revisit the photoevaporation of dust-free disks by solving the 2D axisymmetric radiative transfer for steady-state disks. Unlike that solved by the conventional model, we determine that direct stellar radiation is more important than the diffuse field at the disk surface. The radial density distribution at the ionization boundary is represented by the single power-law with an index -3/2 in contrast to the conventional double power-law. For this distribution, the photoevaporation rate from the entire disk...

  8. Hypogonadotropic Hypogonadism Revisited

    Directory of Open Access Journals (Sweden)

    Renato Fraietta

    2013-01-01

    Full Text Available Impaired testicular function, i.e., hypogonadism, can result from a primary testicular disorder (hypergonadotropic or occur secondary to hypothalamic-pituitary dysfunction (hypogonadotropic. Hypogonadotropic hypogonadism can be congenital or acquired. Congenital hypogonadotropic hypogonadism is divided into anosmic hypogonadotropic hypogonadism (Kallmann syndrome and congenital normosmic isolated hypogonadotropic hypogonadism (idiopathic hypogonadotropic hypogonadism. The incidence of congenital hypogonadotropic hypogonadism is approximately 1-10:100,000 live births, and approximately 2/3 and 1/3 of cases are caused by Kallmann syndrome (KS and idiopathic hypogonadotropic hypogonadism, respectively. Acquired hypogonadotropic hypogonadism can be caused by drugs, infiltrative or infectious pituitary lesions, hyperprolactinemia, encephalic trauma, pituitary/brain radiation, exhausting exercise, abusive alcohol or illicit drug intake, and systemic diseases such as hemochromatosis, sarcoidosis and histiocytosis X. The clinical characteristics of hypogonadotropic hypogonadism are androgen deficiency and a lack/delay/stop of pubertal sexual maturation. Low blood testosterone levels and low pituitary hormone levels confirm the hypogonadotropic hypogonadism diagnosis. A prolonged stimulated intravenous GnRH test can be useful. In Kallmann syndrome, cerebral MRI can show an anomalous morphology or even absence of the olfactory bulb. Therapy for hypogonadotropic hypogonadism depends on the patient's desire for future fertility. Hormone replacement with testosterone is the classic treatment for hypogonadism. Androgen replacement is indicated for men who already have children or have no desire to induce pregnancy, and testosterone therapy is used to reverse the symptoms and signs of hypogonadism. Conversely, GnRH or gonadotropin therapies are the best options for men wishing to have children. Hypogonadotropic hypogonadism is one of the rare conditions in

  9. Cytogenetics of Chilean angiosperms: Advances and prospects Citogenética de angiospermas chilenas: Avances y proyecciones

    Directory of Open Access Journals (Sweden)

    PEDRO JARA-SEGUEL

    2012-03-01

    Full Text Available Cytogenetic data on Chilean angiosperms have been reported since at least eight decades ago; however, much of this information is disperse in diverse sources and is not readily available as a comprehensive document that allows having a general vision on advances and gaps in this matter. The goal of this paper is to summarize the advances and prospets on cytogenetic studies of the Chilean angiosperms based on compiled publications from 1929 to 2010. We found 78 publications supplied by four groups of Chilean researchers and some foreign specialists. Cytogenetic data have been reported for 139 Chilean angiosperm species (2.8 % of the total, which belong to 58 genera and 34 families. During 2001-2010 there was an increase in the number of publications, being available 40 reports including 95 additional species. Based on these data, we hope that such a trend can be maintained in the next decade if the current research groups and young specialists continue to be interested in the study of native plants.Los datos citogenéticos sobre angiospermas chilenas han sido reportados desde al menos ocho décadas atrás; sin embargo, mucha de esta información está dispersa en diversas fuentes y no está disponible como un documento completo que permita tener una visión general sobre los avances y vacíos en esta materia. El objetivo de este trabajo es resumir los avances y proyecciones sobre los estudios citogenéticos disponibles para angiospermas chilenas, basado en publicaciones recopiladas desde 1929 hasta el 2010. Nosotros encontramos 78 publicaciones aportadas por cuatro grupos de investigadores chilenos y por algunos especialistas extranjeros. Datos citogenéticos han sido reportados para 139 especies de angiospermas chilenas (2.8 % del total, las cuales pertenecen a 58 géneros y 34 familias. Durante los años 2001-2010, existió un incremento en el número de publicaciones estando disponibles 40 reportes que incluyen 95 especies adicionales. Basados

  10. The complete nucleotide sequence of the coffee (Coffea arabica L.) chloroplast genome: organization and implications for biotechnology and phylogenetic relationships among angiosperms.

    Science.gov (United States)

    The chloroplast genome sequence of Coffea arabica L., first member of family Rubiaceae (fourth largest family of angiosperms) is reported. The genome is 155,189 bp in length, including a pair of inverted repeats of 25,943 bp, separated by a small single copy region of 18,137 bp and a large single co...

  11. Geranyllinalool synthases in solanaceae and other angiosperms constitute an ancient branch of diterpene synthases involved in the synthesis of defensive compounds

    NARCIS (Netherlands)

    V. Falara; J.M. Alba; M.R. Kant; R.C. Schuurink; E. Pichersky

    2014-01-01

    Many angiosperm plants, including basal dicots, eudicots, and monocots, emit (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene, which is derived from geranyllinalool, in response to biotic challenge. An Arabidopsis (Arabidopsis thaliana) geranyllinalool synthase (GLS) belonging to the e/f clade of the

  12. Measuring chlorophyll a and 14C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer

    International Nuclear Information System (INIS)

    A compound that quantitatively correlated with chlorophyll a could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 600C but rapidly degraded in sunlight or when acidified. 14C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H14CO3, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be use to determine both chlorophyll a content and 14C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material

  13. Measuring chlorophyll α and 14C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer

    International Nuclear Information System (INIS)

    A compound that quantitatively correlated with chlorophyll α could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 600C but rapidly degraded in sunlight or when acidified. 14C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H14CO3, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be used to determine both chlorophyll α content and 14C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams)

  14. The complete chloroplast genome sequence of Citrus sinensis (L. Osbeck var 'Ridge Pineapple': organization and phylogenetic relationships to other angiosperms

    Directory of Open Access Journals (Sweden)

    Jansen Robert K

    2006-09-01

    Full Text Available Abstract Background The production of Citrus, the largest fruit crop of international economic value, has recently been imperiled due to the introduction of the bacterial disease Citrus canker. No significant improvements have been made to combat this disease by plant breeding and nuclear transgenic approaches. Chloroplast genetic engineering has a number of advantages over nuclear transformation; it not only increases transgene expression but also facilitates transgene containment, which is one of the major impediments for development of transgenic trees. We have sequenced the Citrus chloroplast genome to facilitate genetic improvement of this crop and to assess phylogenetic relationships among major lineages of angiosperms. Results The complete chloroplast genome sequence of Citrus sinensis is 160,129 bp in length, and contains 133 genes (89 protein-coding, 4 rRNAs and 30 distinct tRNAs. Genome organization is very similar to the inferred ancestral angiosperm chloroplast genome. However, in Citrus the infA gene is absent. The inverted repeat region has expanded to duplicate rps19 and the first 84 amino acids of rpl22. The rpl22 gene in the IRb region has a nonsense mutation resulting in 9 stop codons. This was confirmed by PCR amplification and sequencing using primers that flank the IR/LSC boundaries. Repeat analysis identified 29 direct and inverted repeats 30 bp or longer with a sequence identity ≥ 90%. Comparison of protein-coding sequences with expressed sequence tags revealed six putative RNA edits, five of which resulted in non-synonymous modifications in petL, psbH, ycf2 and ndhA. Phylogenetic analyses using maximum parsimony (MP and maximum likelihood (ML methods of a dataset composed of 61 protein-coding genes for 30 taxa provide strong support for the monophyly of several major clades of angiosperms, including monocots, eudicots, rosids and asterids. The MP and ML trees are incongruent in three areas: the position of Amborella and

  15. Forensic seismology revisited

    Science.gov (United States)

    Douglas, A.

    2007-01-01

    antinode of P is in the source window is the m b: M s criterion predicted to fail. The results from modelling are consistent with observation—in particular there are earthquakes, “anomalous events”, which look explosion-like on the m b: M s criterion, that turn out to have mechanisms close to 45° dip-slip. Fortunately the P seismograms from such earthquakes usually show pP and sP, the reflections from the free surface of P and S waves radiated upwards. From the pP P and sP P times the focal depth can be estimated. So far the estimated depth of the anomalous events have turned out to be ˜20 km, too deep to be explosions. Studies show that the observation that P seismograms are more complex than predicted by simple models can be explained on the weak-signal hypothesis: the standard phases, direct P and the surface reflections, are weak because of amongst other things, the effects of the radiation pattern or obstacles on the source-to-receiver path; other non-standard arrivals then appear relatively large on the seismograms. What has come out of the modelling of P seismograms is a criterion for recognising suspicious disturbances based on simplicity rather than complexity. Simple P seismograms for earthquakes at depths of more than a few kilometres are likely to be radiated only to stations that lie in a confined range of azimuths and distances. If then, simple seismograms are recorded over a wide range of distances and particularly azimuths, it is unlikely the source is an earthquake at depth. It is possible to test this using the relative amplitudes of direct P and later arrivals that might be surface reflections. The procedure is to use only the simple P seismograms on the assumption that whereas the propagation through Earth may make a signal more complex it is unlikely to make it simpler. From the amplitude of the coda of these seismograms, bounds can be placed on the size of possible pP and sP. The relative-amplitude method is then used to search for

  16. Comparative Genomics of NAC Transcriptional Factors in Angiosperms: Implications for the Adaptation and Diversification of Flowering Plants

    Science.gov (United States)

    Pereira-Santana, Alejandro; Alcaraz, Luis David; Castaño, Enrique; Sanchez-Calderon, Lenin; Sanchez-Teyer, Felipe; Rodriguez-Zapata, Luis

    2015-01-01

    NAC proteins constitute one of the largest groups of plant-specific transcription factors and are known to play essential roles in various developmental processes. They are also important in plant responses to stresses such as drought, soil salinity, cold, and heat, which adversely affect growth. The current knowledge regarding the distribution of NAC proteins in plant lineages comes from relatively small samplings from the available data. In the present study, we broadened the number of plant species containing the NAC family origin and evolution to shed new light on the evolutionary history of this family in angiosperms. A comparative genome analysis was performed on 24 land plant species, and NAC ortholog groups were identified by means of bidirectional BLAST hits. Large NAC gene families are found in those species that have experienced more whole-genome duplication events, pointing to an expansion of the NAC family with divergent functions in flowering plants. A total of 3,187 NAC transcription factors that clustered into six major groups were used in the phylogenetic analysis. Many orthologous groups were found in the monocot and eudicot lineages, but only five orthologous groups were found between P. patens and each representative taxa of flowering plants. These groups were called basal orthologous groups and likely expanded into more recent taxa to cope with their environmental needs. This analysis on the angiosperm NAC family represents an effort to grasp the evolutionary and functional diversity within this gene family while providing a basis for further functional research on vascular plant gene families. PMID:26569117

  17. Expansion and diversification of BTL ring-H2 ubiquitin ligases in angiosperms: putative Rabring7/BCA2 orthologs.

    Science.gov (United States)

    Aguilar-Hernández, Victor; Medina, Juliana; Aguilar-Henonin, Laura; Guzmán, Plinio

    2013-01-01

    RING finger E3 ligases are components of the ubiquitin proteasome system (UPS) that mediate the transfer of ubiquitin to substrates. Single-subunit RING finger E3s binds the E2 ubiquitin-conjugating enzyme and contains recognition sequences for the substrate within the same polypeptide. Here we describe the characterization of a class of RING finger E3 ligases that is conserved among eukaryotes. This class encodes a RING-H2 domain related in sequence to the ATL RING-H2 domain, another class of E3 ligases, and a C2/C2 zing finger at the amino-terminus, formerly described as BZF. In viridiplantae (green algae and land plants), we designed this family as BTL for BZF ATLs. BTLs are putative orthologs of the mammalian Rabring7/BCA2 RING-H2 E3s that have expanded in angiosperms. They are found in numbers ranging from three to thirty-one, which is in contrast to the one to three members normally found in animals, fungi, and protists. Furthermore, the number of sequence LOGOs generated in angiosperms is four times greater than that in other eukaryotes. In contrast to ATLs, which show expansion by tandem duplication, tandemly duplicated BTLs are scarce. The mode of action of Rabring7/BCA2 and BTLs may be similar since both the Rabring7/BCA2 BZF and the ath|BTL4 BZF are likely to mediate the binding of ubiquitin. This study introduces valuable information on the evolution and domain structure of the Rabring7/BCA2/BTL class of E3 ligases which may be important for core eukaryotic genes. PMID:23951330

  18. Scaling of stomatal size and density optimizes allocation of leaf epidermal space for gas exchange in angiosperms

    Science.gov (United States)

    de Boer, Hugo Jan; Price, Charles A.; Wagner-Cremer, Friederike; Dekker, Stefan C.; Franks, Peter J.; Veneklaas, Erik J.

    2015-04-01

    Stomata on plant leaves are key traits in the regulation of terrestrial fluxes of water and carbon. The basic morphology of stomata consists of a diffusion pore and two guard cells that regulate the exchange of CO2 and water vapour between the leaf interior and the atmosphere. This morphology is common to nearly all land plants, yet stomatal size (defined as the area of the guard cell pair) and stomatal density (the number of stomata per unit area) range over three orders of magnitude across species. Evolution of stomatal sizes and densities is driven by selection pressure on the anatomical maximum stomatal conductance (gsmax), which determines the operational range of leaf gas exchange. Despite the importance of stomata traits for regulating leaf gas exchange, a quantitative understanding of the relation between adaptation of gsmax and the underlying co-evolution of stomatal sizes and densities is still lacking. Here we develop a theoretical framework for a scaling relationship between stomatal sizes and densities within the constraints set by the allocation of epidermal space and stomatal gas exchange. Our theory predicts an optimal scaling relationship that maximizes gsmax and minimizes epidermal space allocation to stomata. We test whether stomatal sizes and densities reflect this optimal scaling with a global compilation of stomatal trait data on 923 species reflecting most major clades. Our results show optimal scaling between stomatal sizes and densities across all species in the compiled data set. Our results also show optimal stomatal scaling across angiosperm species, but not across gymnosperm and fern species. We propose that the evolutionary flexibility of angiosperms to adjust stomatal sizes underlies their optimal allocation of leaf epidermal space to gas exchange.

  19. A remote coal deposit revisited

    DEFF Research Database (Denmark)

    Bojesen-Kofoed, Jørgen A.; Kalkreuth, Wolfgang; Petersen, Henrik I.;

    2012-01-01

    In 1908, members of the “Danmark Expedition” discovered a coal deposit in a very remote area in western Germania Land, close to the margin of the inland ice in northeast Greenland. The deposit was, however, neither sampled nor described, and was revisited in 2009 for the first time since its...... discovery. The outcrops found in 2009 amount to approximately 8 m of sediment including a coal seam of 2 m thickness. More outcrops and additional coal deposits most certainly are to be found, pending further fieldwork. The deposits are Middle Jurassic, Callovian, in age and were deposited in a floodplain...... environment related to meandering river channels. Spores and pollen in the lower fluvial deposits reflect abundant vegetation of ferns along the river banks. In contrast, a sparse spore and pollen flora in the coals show a mixed vegetation of ferns and gymnosperms. Based on proximate and petrographic analyses...

  20. Angiosperms Are Unique among Land Plant Lineages in the Occurrence of Key Genes in the RNA-Directed DNA Methylation (RdDM) Pathway.

    Science.gov (United States)

    Ma, Lu; Hatlen, Andrea; Kelly, Laura J; Becher, Hannes; Wang, Wencai; Kovarik, Ales; Leitch, Ilia J; Leitch, Andrew R

    2015-09-01

    The RNA-directed DNA methylation (RdDM) pathway can be divided into three phases: 1) small interfering RNA biogenesis, 2) de novo methylation, and 3) chromatin modification. To determine the degree of conservation of this pathway we searched for key genes among land plants. We used OrthoMCL and the OrthoMCL Viridiplantae database to analyze proteomes of species in bryophytes, lycophytes, monilophytes, gymnosperms, and angiosperms. We also analyzed small RNA size categories and, in two gymnosperms, cytosine methylation in ribosomal DNA. Six proteins were restricted to angiosperms, these being NRPD4/NRPE4, RDM1, DMS3 (defective in meristem silencing 3), SHH1 (SAWADEE homeodomain homolog 1), KTF1, and SUVR2, although we failed to find the latter three proteins in Fritillaria persica, a species with a giant genome. Small RNAs of 24 nt in length were abundant only in angiosperms. Phylogenetic analyses of Dicer-like (DCL) proteins showed that DCL2 was restricted to seed plants, although it was absent in Gnetum gnemon and Welwitschia mirabilis. The data suggest that phases (1) and (2) of the RdDM pathway, described for model angiosperms, evolved with angiosperms. The absence of some features of RdDM in F. persica may be associated with its large genome. Phase (3) is probably the most conserved part of the pathway across land plants. DCL2, involved in virus defense and interaction with the canonical RdDM pathway to facilitate methylation of CHH, is absent outside seed plants. Its absence in G. gnemon, and W. mirabilis coupled with distinctive patterns of CHH methylation, suggest a secondary loss of DCL2 following the divergence of Gnetales. PMID:26338185

  1. Identifying the Basal Angiosperm Node in Chloroplast GenomePhylogenies: Sampling One's Way Out of the Felsenstein Zone

    Energy Technology Data Exchange (ETDEWEB)

    Leebens-Mack, Jim; Raubeson, Linda A.; Cui, Liying; Kuehl,Jennifer V.; Fourcade, Matthew H.; Chumley, Timothy W.; Boore, JeffreyL.; Jansen, Robert K.; dePamphilis, Claude W.

    2005-05-27

    While there has been strong support for Amborella and Nymphaeales (water lilies) as branching from basal-most nodes in the angiosperm phylogeny, this hypothesis has recently been challenged by phylogenetic analyses of 61 protein-coding genes extracted from the chloroplast genome sequences of Amborella, Nymphaea and 12 other available land plant chloroplast genomes. These character-rich analyses placed the monocots, represented by three grasses (Poaceae), as sister to all other extant angiosperm lineages. We have extracted protein-coding regions from draft sequences for six additional chloroplast genomes to test whether this surprising result could be an artifact of long-branch attraction due to limited taxon sampling. The added taxa include three monocots (Acorus, Yucca and Typha), a water lily (Nuphar), a ranunculid(Ranunculus), and a gymnosperm (Ginkgo). Phylogenetic analyses of the expanded DNA and protein datasets together with microstructural characters (indels) provided unambiguous support for Amborella and the Nymphaeales as branching from the basal-most nodes in the angiospermphylogeny. However, their relative positions proved to be dependent on method of analysis, with parsimony favoring Amborella as sister to all other angiosperms, and maximum likelihood and neighbor-joining methods favoring an Amborella + Nympheales clade as sister. The maximum likelihood phylogeny supported the later hypothesis, but the likelihood for the former hypothesis was not significantly different. Parametric bootstrap analysis, single gene phylogenies, estimated divergence dates and conflicting in del characters all help to illuminate the nature of the conflict in resolution of the most basal nodes in the angiospermphylogeny. Molecular dating analyses provided median age estimates of 161 mya for the most recent common ancestor of all extant angiosperms and 145 mya for the most recent common ancestor of monocots, magnoliids andeudicots. Whereas long sequences reduce variance in

  2. NLTE in a Hot Hydrogen Star: Auer & Mihalas Revisited

    Science.gov (United States)

    Wiersma, J.; Rutten, R. J.; Lanz, T.

    2003-01-01

    We pay tribute to two landmark papers published by Auer & Mihalas in 1969. They modeled hot-star NLTE-RE hydrogen-only atmospheres, using two simplified hydrogen atoms: ApJ 156, 157: H I levels 1, 2 and c, Lyman α the only line ApJ 156, 681: H I levels 1, 2, 3 and c, Balmer α the only line and computed LTE and NLTE models with the single line turned on and off. The results were extensively analyzed in the two papers. Any student of stellar line formation should take these beautiful papers to heart. The final exercise in Rutten's lecture notes ``Radiative Transfer in Stellar Atmospheres'' asks the student to work through five pages of questions concerning diagrams from the first paper alone! That exercise led to the present work in which we recompute the Auer-Mihalas hot-hydrogen-star models with TLUSTY, adding results from a complete hydrogen atom for comparison. Our motivation for this Auer-Mihalas re-visitation is twofold: 1. to add diagnostic diagrams to the ones published by Auer & Mihalas, in particular Bν, Jν, Sν graphs to illustrate the role of the radiation field, and radiative heating & cooling graphs to illustrate the radiative energy budget, 2. to see the effect of adding the rest of the hydrogen atom.

  3. Divergent expression patterns of miR164 and CUP-SHAPED COTYLEDON genes in palms and other monocots : implication for the evolution of meristem function in angiosperms

    OpenAIRE

    Adam, Hélène; Marguerettaz, M.; Qadri, R.; Adroher, B.; Richaud, F; Collin, Myriam; Thuillet, Anne-Céline; Vigouroux, Yves; Laufs, P.; Tregear, James; Jouannic, Stefan

    2011-01-01

    In order to understand how the morphology of plant species has diversified over time, it is necessary to decipher how the underlying developmental programs have evolved. The regulatory network controlling shoot meristem activity is likely to have played an important role in morphological diversification and useful insights can be gained by comparing monocots and eudicots. These two distinct monophyletic groups of angiosperms diverged 130 Ma and are characterized by important differences in th...

  4. Fine structure of the butterfly diagram revisited

    Science.gov (United States)

    Major, Balázs

    The latitudinal time distribution of sunspots (butterfly diagram) was studied by Becker (1959) and Antalová & Gnevyshev (1985). Our goal is to revisit these studies. In the first case we check whether there is a poleward migration in sunspot activity. In the second case we confirm the results, and make more quantitative statements concerning their significance and the position of the activity peaks.

  5. The Rotating Morse-Pekeris Oscillator Revisited

    Science.gov (United States)

    Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

    2008-01-01

    The Morse-Pekeris oscillator model for the calculation of the vibration-rotation energy levels of diatomic molecules is revisited. This model is based on the realization of a second-order exponential expansion of the centrifugal term about the minimum of the vibrational Morse oscillator and the subsequent analytical resolution of the resulting…

  6. Patterns of ROS Accumulation in the Stigmas of Angiosperms and Visions into Their Multi-Functionality in Plant Reproduction.

    Science.gov (United States)

    Zafra, Adoración; Rejón, Juan D; Hiscock, Simon J; Alché, Juan de Dios

    2016-01-01

    Accumulation of reactive oxygen species (ROS) in the stigma of several plant species has been investigated. Four developmental stages (unopened flower buds, recently opened flowers, dehiscent anthers, and flowers after fertilization) were analyzed by confocal laser scanning microscopy using the ROS-specific probe DCFH2-DA. In all plants scrutinized, the presence of ROS in the stigmas was detected at higher levels during those developmental phases considered "receptive" to pollen interaction. In addition, these molecules were also present at early (unopened flower) or later (post-fertilization) stages, by following differential patterns depending on the different species. The biological significance of the presence ROS may differ between these stages, including defense functions, signaling and senescence. Pollen-stigma signaling is likely involved in the different mechanisms of self-incompatibility in these plants. The study also register a general decrease in the presence of ROS in the stigmas upon pollination, when NO is supposedly produced in an active manner by pollen grains. Finally, the distribution of ROS in primitive Angiosperms of the genus Magnolia was determined. The production of such chemical species in these plants was several orders of magnitude higher than in the remaining species evoking a massive displacement toward the defense function. This might indicate that signaling functions of ROS/NO in the stigma evolved later, as fine tune likely involved in specialized interactions like self-incompatibility. PMID:27547207

  7. A gene family derived from transposable elements during early angiosperm evolution has reproductive fitness benefits in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Zoé Joly-Lopez

    2012-09-01

    Full Text Available The benefits of ever-growing numbers of sequenced eukaryotic genomes will not be fully realized until we learn to decipher vast stretches of noncoding DNA, largely composed of transposable elements. Transposable elements persist through self-replication, but some genes once encoded by transposable elements have, through a process called molecular domestication, evolved new functions that increase fitness. Although they have conferred numerous adaptations, the number of such domesticated transposable element genes remains unknown, so their evolutionary and functional impact cannot be fully assessed. Systematic searches that exploit genomic signatures of natural selection have been employed to identify potential domesticated genes, but their predictions have yet to be experimentally verified. To this end, we investigated a family of domesticated genes called MUSTANG (MUG, identified in a previous bioinformatic search of plant genomes. We show that MUG genes are functional. Mutants of Arabidopsis thaliana MUG genes yield phenotypes with severely reduced plant fitness through decreased plant size, delayed flowering, abnormal development of floral organs, and markedly reduced fertility. MUG genes are present in all flowering plants, but not in any non-flowering plant lineages, such as gymnosperms, suggesting that the molecular domestication of MUG may have been an integral part of early angiosperm evolution. This study shows that systematic searches can be successful at identifying functional genetic elements in noncoding regions and demonstrates how to combine systematic searches with reverse genetics in a fruitful way to decipher eukaryotic genomes.

  8. Moisture availability constraints on the leaf area to sapwood area ratio: analysis of measurements on Australian evergreen angiosperm trees

    Science.gov (United States)

    Togashi, Henrique; Prentice, Colin; Evans, Bradley; Forrester, David; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2014-05-01

    The leaf area to sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. Pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease towards drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. We found considerable scatter in LA:SA among species. However quantile regression showed strong (0.2

  9. Revisiting the 1761 Transatlantic Tsunami

    Science.gov (United States)

    Baptista, Maria Ana; Wronna, Martin; Miranda, Jorge Miguel

    2016-04-01

    The tsunami catalogs of the Atlantic include two transatlantic tsunamis in the 18th century the well known 1st November 1755 and the 31st March 1761. The 31st March 1761 earthquake struck Portugal, Spain, and Morocco. The earthquake occurred around noontime in Lisbon alarming the inhabitants and throwing down ruins of the past 1st November 1755 earthquake. According to several sources, the earthquake was followed by a tsunami observed as far as Cornwall (United Kingdom), Cork (Ireland) and Barbados (Caribbean). The analysis of macroseismic information and its compatibility with tsunami travel time information led to a source area close to the Ampere Seamount with an estimated epicenter circa 34.5°N 13°W. The estimated magnitude of the earthquake was 8.5. In this study, we revisit the tsunami observations, and we include a report from Cadiz not used before. We use the results of the compilation of the multi-beam bathymetric data, that covers the area between 34°N - 38°N and 12.5°W - 5.5°W and use the recent tectonic map published for the Southwest Iberian Margin to select among possible source scenarios. Finally, we use a non-linear shallow water model that includes the discretization and explicit leap-frog finite difference scheme to solve the shallow water equations in the spherical or Cartesian coordinate to compute tsunami waveforms and tsunami inundation and check the results against the historical descriptions to infer the source of the event. This study received funding from project ASTARTE- Assessment Strategy and Risk Reduction for Tsunamis in Europe a collaborative project Grant 603839, FP7-ENV2013 6.4-3

  10. Noncommutative information is revealed from Hawking radiation as tunneling

    Science.gov (United States)

    Zhang, Baocheng; Cai, Qing-yu; Zhan, Ming-sheng; You, Li

    2011-04-01

    We revisit the tunneling process from a Schwarzschild black hole in the noncommutative spacetime and obtain the nonthermal tunneling probability. In such nonthermal spectrum, the correlations are discovered, which can carry the information about the noncommutativity. Thus this enlightens a way to find the noncommutative information in the Hawking radiation. The entropy is also shown to be conserved in the whole radiation process, which implies that the unitarity is held even for the Hawking radiation from noncommutative black holes.

  11. Noncommutative information is revealed from Hawking radiation as tunneling

    CERN Document Server

    Zhang, Baocheng; Zhan, Ming-sheng; You, Li

    2013-01-01

    We revisit the tunneling process from a Schwarzschild black hole in the noncommutative spacetime and obtain the non-thermal tunneling probability. In such non-thermal spectrum, the correlations are discovered, which can carry the information about the noncommutativity. Thus this enlightens a way to find the noncommutative information in the Hawking radiation. The entropy is also shown to be conserved in the whole radiation process, which implies that the unitarity is held even for the Hawking radiation from noncommutative black holes.

  12. Evidence for radiations of cheilanthoid ferns in the Greater Cape Floristic Region

    DEFF Research Database (Denmark)

    Eiserhardt, Wolf L.; Rohwer, Jens G.; Russell, Stephen J.;

    2011-01-01

    The Greater Cape Floristic Region (GCFR) of southern Africa is characterised by large, endemic radiations of flowering plants, the so-called ‘Cape Clades’, but it is unknown whether such radiations are also found in non-angiosperms. We hypothesise that GCFR-endemic lineages exist in the xeric...... cheilanthoid fern species occurring in the GCFR. With two exceptions, all GCFR-endemics are part of two clades that diversified in the Afro-Madagascan region. The GCFR-endemics are further concentrated in three high-endemism subclades that did not originate simultaneously, but within the timeframe of...... angiosperm Cape Clades diversification. According to ancestral area reconstructions the ancestors of the two larger Afro-Madagascan clades were likely GCFR-endemic, and a substantial part of the diversification history of these clades took place in the GCFR. The high diversity of cheilanthoids in the GCFR...

  13. Useful ethnophytomedicinal recipes of angiosperms used against diabetes in South East Asian Countries (India, Pakistan & Sri Lanka).

    Science.gov (United States)

    Marwat, Sarfaraz Khan; Rehman, Fazalur; Khan, Ejaz Ahmad; Khakwani, Abdul Aziz; Ullah, Imdad; Khan, Kaleem Ullah; Khan, Inam Ullah

    2014-09-01

    This paper is based on data recorded from various literatures pertaining to ethnophytomedicinal recipes used against diabetes in South East Asia (India, Pakistan and Srilanka). Traditional plant treatments have been used throughout the world for the therapy of diabetes mellitus. In total 419 useful phytorecipes of 270 plant species belonging to 74 Angiospermic families were collected. From the review it was revealed that plants showing hypoglycemic potential mainly belong to the families, Cucurbitaceae (16 spp.), Euphorbiaceae (15 spp.), Caesalpiniaceae and Papilionaceae (13 spp. each), Moraceae (11 spp.), Acanthaceae (10 spp.), Mimosaceae (09 spp.), Asteraceae, Malvaceae and Poaceae (08 spp. each), Hippocrateaceae, Rutaceae and Zingiberaceae (07 spp. each), Apocynaceae, Asclepiadaceae and Verbenaceae (06 spp. each), Apiaceae, Convolvulaceae, Lamiaceae, Myrtaceae, Solanaceae (05 spp.each). The most active plants are Syzigium cumini (14 recipes), Phyllanthus emblica (09 recipes), Centella asiatica and Momordica charantia (08 recipes each), Azadirachta indica (07 recipes), Aegle marmelos, Catharanthus roseus, Ficus benghalensis, Ficus racemosa, Gymnema sylvestre (06 recipes each), Allium cepa, A. sativum, Andrographis paniculata, Curcuma longa (05 recipes each), Citrullus colocynthis, Justicia adhatoda, Nelumbo nucifera, Tinospora cordifolia, Trigonella foenum-graecum, Ziziphus mauritiana and Wattakaka volubilis (4 recipes each). These traditional recipes include extracts, leaves, powders, flour, seeds, vegetables, fruits and herbal mixtures. Data inventory consists of botanical name, recipe, vernacular name, English name. Some of the plants of the above data with experimentally confirmed antidiabetic properties have also been recorded. More investigations must be carried out to evaluate the mechanism of action of diabetic medicinal plants. Toxicity of these plants should also be explained. Scientific validation of these recipes may help in discovering new drugs from

  14. Citogenética de Angiospermas coletadas em Pernambuco: V Cytogenetics of Angiosperms collected in the State of Pernambuco: V

    Directory of Open Access Journals (Sweden)

    Andrea Pedrosa

    1999-04-01

    Full Text Available Foram analisadas 33 espécies, entre nativas e introduzidas, pertencentes a 20 famílias de angiospermas ocorrentes no Estado de Pernambuco. A caracterização cariotípica da maioria das espécies foi baseada no número e morfologia cromossômica, padrão de condensação de cromossomos profásicos e estrutura de núcleo interfásico. Cinco espécies tiveram seus números cromossômicos determinados pela primeira vez, sendo elas: Cereus jamacaru (2n=22, Clitoria fairchildiana (2n=22, Eugenia luschnathiana (2n=22, Licania tomentosa (2n=22 e Spondias tuberosa (n=16. No caso de Licania tomentosa esta é a primeira citação de número cromossômico para o gênero. Das outras 28 espécies, três (Cecropia cf. palmata, 2n=26; Crinum erubescens, 2n=70; e Schinus terebentifolius, 2n=28 apresentaram números cromossômicos diferentes dos registrados previamente na literatura.Thirty three native and introduced species from 20 families of angiosperms collected in the State of Pernambuco were analysed. The karyotype description of the majority of the species was based on chromosome number and morphology, condensation pattern of prophase chromosomes as well as interphase nuclear structure. In five species (Cereus jamacaru, 2n=22; Clitoria fairchildiana, 2n=22; Eugenia luschnathiana, 2n=22; Licania tomentosa, 2n=22; and Spondias tuberosa, n=16 the chromosome number is reported here for the first time. In the case of Licania tomentosa, this is also the first report for the genus. Among the other 28 species, three (Cecropia cf. palmata, 2n=26; Crinum erubescens, 2n=70; and Schinus terebentifolius, 2n=28 showed chromosome numbers different from what has previously been reported.

  15. Revisiting Pattern Structures for Structured Attribute Sets

    OpenAIRE

    Alam, Mehwish; Buzmakov, Aleksey; Napoli, Amedeo; Sailanbayev, Alibek

    2015-01-01

    In this paper, we revisit an original proposition on pattern structures for structured sets of attributes. There are several reasons for carrying out this kind of research work. The original proposition does not give many details on the whole framework, and especially on the possible ways of implementing the similarity operation. There exists an alternative definition without any reference to pattern structures, and we would like to make a parallel between two points of view. Moreover we disc...

  16. Hyperinflation in Brazil, Israel, and Nicaragua revisited

    OpenAIRE

    Szybisz, M. A.; Szybisz, L.

    2016-01-01

    The aim of this work is to address the description of hyperinflation regimes in economy. The spirals of hyperinflation developed in Brazil, Israel, and Nicaragua are revisited. This new analysis of data indicates that the episodes occurred in Brazil and Nicaragua can be understood within the frame of the model available in the literature, which is based on a nonlinear feedback (NLF) characterized by an exponent $\\beta>0$. In the NLF model the accumulated consumer price index carries a finite ...

  17. Directed animals and Gas Models Revisited

    OpenAIRE

    Le Borgne, Yvan; Marckert, Jean-François

    2007-01-01

    In this paper, we revisit the enumeration of directed animals using gas models. We show that there exists a natural construction of random directed animals on any directed graph together with a particle system that explains at the level of objects the formal link known between the density of the gas model and the generating function of directed animals counted according to the area. This provides some new methods to compute the generating function of directed animals counted according to area...

  18. THE MATHEMATICAL FOUNDATIONS OF GENERAL RELATIVITY REVISITED

    OpenAIRE

    Jean-Francois Pommaret

    2013-01-01

    The purpose of this paper is to present for the first time an elementary summary of a few recent results obtained through the application of the formal theory of partial differential equations and Lie pseudogroups in order to revisit the mathematical foundations of general relativity. Other engineering examples (control theory, elasticity theory, electromagnetism) will also be considered in order to illustrate the three fundamental results that we shall provide successively. 1) VESSIOT VERSU...

  19. Revisiting the texture zero neutrino mass matrices

    CERN Document Server

    Singh, Madan; Gupta, Manmohan

    2016-01-01

    In the light of refined and large reactor mixing angle $\\theta_{13}$, we have revisited the texture three and two zero neutrino mass matrices in the flavor basis. For Majorana neutrinos, it has been explicitly shown that all the texture three zero mass matrices remain ruled out. Further, for both normal and inverted mass ordering, for the texture two zero neutrino mass matrices one finds interesting constraints on the Dirac-like CP violating phase $\\delta$ and Majorana phases $\\rho$ and $\\sigma$.

  20. Parallel R&D Paths Revisited

    OpenAIRE

    Scherer, Frederic Michael

    2011-01-01

    This paper revisits the logic of pursuing parallel R&D paths when there is uncertainty as to which approaches will succeed technically and/or economically. The previous findings by Richard Nelson and the present author are reviewed. A further analysis then seeks to determine how sensitive optimal strategies are to parameter variations and the extent to which parallel and series strategies are integrated. It pays to support more approaches, the deeper the stream of benefits is and the lower is...

  1. Szemer\\'edi's regularity lemma revisited

    OpenAIRE

    2005-01-01

    Szemer\\'edi's regularity lemma is a basic tool in graph theory, and also plays an important role in additive combinatorics, most notably in proving Szemer\\'edi's theorem on arithmetic progressions . In this note we revisit this lemma from the perspective of probability theory and information theory instead of graph theory, and observe a variant of this lemma which introduces a new parameter $F$. This stronger version of the regularity lemma was iterated in a recent paper of the author to repr...

  2. Spine revisited: Principles and parlance redefined

    Directory of Open Access Journals (Sweden)

    Kothari M

    2005-01-01

    Full Text Available A revised appreciation of the evolution and the nature of bone in general and of vertebrae in particular, allows revisiting the human spine to usher in some new principles and more rational parlance, that embody spine′s phylogeny, ontogeny, anatomy and physiology. Such an approach accords primacy to spine′s soft-tissues, and relegates to its bones a secondary place.

  3. ConocoPhillips’ share price model revisited

    OpenAIRE

    Kitov, Ivan

    2012-01-01

    Three years ago we found a statistically reliable link between ConocoPhillips’ (NYSE: COP) stock price and the difference between the core and headline CPI in the United States. In this article, the original relationship is revisited with new data available since 2009. The agreement between the observed monthly closing price (adjusted for dividends and splits) and that predicted from the CPI difference is confirmed. The original quantitative link is validated. In order to improve the accurac...

  4. The plastid genome of Najas flexilis: adaptation to submersed environments is accompanied by the complete loss of the NDH complex in an aquatic angiosperm.

    Directory of Open Access Journals (Sweden)

    Elena L Peredo

    Full Text Available The re-colonization of aquatic habitats by angiosperms has presented a difficult challenge to plants whose long evolutionary history primarily reflects adaptations to terrestrial conditions. Many aquatics must complete vital stages of their life cycle on the water surface by means of floating or emergent leaves and flowers. Only a few species, mainly within the order Alismatales, are able to complete all aspects of their life cycle including pollination, entirely underwater. Water-pollinated Alismatales include seagrasses and water nymphs (Najas, the latter being the only freshwater genus in the family Hydrocharitaceae with subsurface water-pollination. We have determined the complete nucleotide sequence of the plastid genome of Najas flexilis. The plastid genome of N. flexilis is a circular AT-rich DNA molecule of 156 kb, which displays a quadripartite structure with two inverted repeats (IR separating the large single copy (LSC from the small single copy (SSC regions. In N. flexilis, as in other Alismatales, the rps19 and trnH genes are localized in the LSC region instead of within the IR regions as in other monocots. However, the N. flexilis plastid genome presents some anomalous modifications. The size of the SSC region is only one third of that reported for closely related species. The number of genes in the plastid is considerably less. Both features are due to loss of the eleven ndh genes in the Najas flexilis plastid. In angiosperms, the absence of ndh genes has been related mainly to the loss of photosynthetic function in parasitic plants. The ndh genes encode the NAD(PH dehydrogenase complex, believed essential in terrestrial environments, where it increases photosynthetic efficiency in variable light intensities. The modified structure of the N. flexilis plastid genome suggests that adaptation to submersed environments, where light is scarce, has involved the loss of the NDH complex in at least some photosynthetic angiosperms.

  5. The plastid genome of Najas flexilis: adaptation to submersed environments is accompanied by the complete loss of the NDH complex in an aquatic angiosperm.

    Science.gov (United States)

    Peredo, Elena L; King, Ursula M; Les, Donald H

    2013-01-01

    The re-colonization of aquatic habitats by angiosperms has presented a difficult challenge to plants whose long evolutionary history primarily reflects adaptations to terrestrial conditions. Many aquatics must complete vital stages of their life cycle on the water surface by means of floating or emergent leaves and flowers. Only a few species, mainly within the order Alismatales, are able to complete all aspects of their life cycle including pollination, entirely underwater. Water-pollinated Alismatales include seagrasses and water nymphs (Najas), the latter being the only freshwater genus in the family Hydrocharitaceae with subsurface water-pollination. We have determined the complete nucleotide sequence of the plastid genome of Najas flexilis. The plastid genome of N. flexilis is a circular AT-rich DNA molecule of 156 kb, which displays a quadripartite structure with two inverted repeats (IR) separating the large single copy (LSC) from the small single copy (SSC) regions. In N. flexilis, as in other Alismatales, the rps19 and trnH genes are localized in the LSC region instead of within the IR regions as in other monocots. However, the N. flexilis plastid genome presents some anomalous modifications. The size of the SSC region is only one third of that reported for closely related species. The number of genes in the plastid is considerably less. Both features are due to loss of the eleven ndh genes in the Najas flexilis plastid. In angiosperms, the absence of ndh genes has been related mainly to the loss of photosynthetic function in parasitic plants. The ndh genes encode the NAD(P)H dehydrogenase complex, believed essential in terrestrial environments, where it increases photosynthetic efficiency in variable light intensities. The modified structure of the N. flexilis plastid genome suggests that adaptation to submersed environments, where light is scarce, has involved the loss of the NDH complex in at least some photosynthetic angiosperms. PMID:23861923

  6. Geranyllinalool synthases in solanaceae and other angiosperms constitute an ancient branch of diterpene synthases involved in the synthesis of defensive compounds

    OpenAIRE

    Falara, V.; Alba, J.M.; Kant, M.R.; Schuurink, R. C.; Pichersky, E

    2014-01-01

    Many angiosperm plants, including basal dicots, eudicots, and monocots, emit (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene, which is derived from geranyllinalool, in response to biotic challenge. An Arabidopsis (Arabidopsis thaliana) geranyllinalool synthase (GLS) belonging to the e/f clade of the terpene synthase (TPS) family and two Fabaceae GLSs that belong to the TPS-g clade have been reported, making it unclear which is the main route to geranyllinalool in plants. We characterized a to...

  7. Radiative decays of mesons in the NJL model

    CERN Document Server

    Epele, L N; Dumm, D G; Grunfeld, A G

    2001-01-01

    We revisit the theoretical predictions for anomalous radiative decays of pseudoscalar and vector mesons. Our analysis is performed in the framework of the Nambu-Jona-Lasinio model, introducing adequate parameters to account for the breakdown of chiral symmetry. The results are comparable with those obtained in previous approaches.

  8. Revisiting radiation patterns in e+e- collisions

    International Nuclear Information System (INIS)

    We propose four simple event-shape variables for semi-inclusive e+e-→4-jet events. The observables and cuts are designed to be especially sensitive to subleading aspects of the event structure, and allow to test the reliability of phenomenological QCD models in greater detail. Three of them, θ14, θ*, and C(1/5)2, focus on soft emissions off three-jet topologies with a small opening angle, for which coherence effects beyond the leading QCD dipole pattern are expected to be enhanced. A complementary variable, M2L/M2H, measures the ratio of the hemisphere masses in 4-jet events with a compressed scale hierarchy (Durham y23∝y34), for which subleading 1→3 splitting effects are expected to be enhanced. We consider several different parton-shower models, spanning both conventional and dipole/antenna ones, all tuned to the same e+e- reference data, and show that a measurement of the proposed observables would allow for additional significant discriminating power between the models.

  9. Revisiting Radiation Patterns in $e^+e^-$ Collisions

    CERN Document Server

    Fischer, Nadine; Plätzer, Simon; Skands, Peter

    2014-01-01

    We propose four simple event-shape variables for semi-inclusive $e^+e^- \\to 4$-jet events. The observables and cuts are designed to be especially sensitive to subleading aspects of the event structure, and allow to test the reliability of phenomenological QCD models in greater detail. Three of them, $\\theta_{14}$, $\\theta^*$, and $C_2^{(1/5)}$, focus on soft emissions off three-jet topologies with a small opening angle, for which coherence effects beyond the leading QCD dipole pattern are expected to be enhanced. A complementary variable, $M_L^2/M_H^2$, measures the ratio of the hemisphere masses in 4-jet events with a compressed scale hierarchy (Durham $y_{23}\\sim y_{34}$), for which subleading $1\\to 3$ splitting effects are expected to be enhanced. We consider several different parton-shower models, spanning both conventional and dipole/antenna ones, all tuned to the same $e^+e^-$ reference data, and show that a measurement of the proposed observables would allow for additional significant discriminating po...

  10. Running of Radiative Neutrino Masses: The Scotogenic Model - REVISITED

    CERN Document Server

    Merle, Alexander

    2015-01-01

    A few years ago, it had been shown that effects stemming from renormalisation group running can be quite large in the scotogenic model, where neutrinos obtain their mass only via a 1-loop diagram (or, more generally, in many models in which the light neutrino mass is generated via quantum corrections at loop-level). We present a new computation of the renormalisation group equations (RGEs) for the scotogenic model, thereby updating previous results. We discuss the matching in detail, in particular in what regards the different mass spectra possible for the new particles involved. We furthermore develop approximate analytical solutions to the RGEs for an extensive list of illustrative cases, covering all general tendencies that can appear in the model. Comparing them with fully numerical solutions, we give a comprehensive discussion of the running in the scotogenic model. Our approach is mainly top-down, but we also discuss an attempt to get information on the values of the fundamental parameters when inputtin...

  11. Revisiting Discrete Dark Matter Model:\\theta_{13}\

    CERN Document Server

    Hamada, Yuta; Ogasahara, Atsushi; Omura, Yuji; Takayama, Fumihiro; Yasuhara, Daiki

    2014-01-01

    We revisit the discrete dark matter model with $A_4$ flavor symmetry originally introduced by M.Hirsch {\\it et.al}. We show that radiative corrections can lead to non-zero $\\theta_{13}$ and non-zero mass for the lightest neutrino. We find an interesting relation among neutrino mixing parameters and it indicates the sizable deviation of $s_{23}$ from the maximal angle $s_{23}^2=1/2$ and the degenerate mass spectrum for neutrinos. Also we study the possibilities that the right-handed neutrino is a dark matter candidate. Assuming the thermal freeze-out explains observed dark matter abundance, TeV-scale right-handed neutrino and flavored scalar bosons are required. In such a case, flavor symmetry plays an important role for the suppression of lepton flavor violating processes as well as for the stability of dark matter. We show that this scenario can be viable against currently existing constraints from collider, low energy experiments and cosmological observations.

  12. Darwin-Wallace Demons: survival of the fastest in populations of duckweeds and the evolutionary history of an enigmatic group of angiosperms.

    Science.gov (United States)

    Kutschera, U; Niklas, K J

    2015-01-01

    In evolutionary biology, the term 'Darwinian fitness' refers to the lifetime reproductive success of an individual within a population of conspecifics. The idea of a 'Darwinian Demon' emerged from this concept and is defined here as an organism that commences reproduction almost immediately after birth, has a maximum fitness, and lives forever. It has been argued that duckweeds (sub-family Lemnoideae, order Alismatales), a group containing five genera and 34 species of small aquatic monocotyledonous plants with a reduced body plan, can be interpreted as examples of 'Darwinian Demons'. Here we focus on the species Spirodela polyrhiza (Great duckweed) and show that these miniaturised aquatic angiosperms display features that fit the definition of the hypothetical organism that we will call a 'Darwin-Wallace Demon' in recognition of the duel proponents of evolution by natural selection. A quantitative analysis (log-log bivariate plot of annual growth in dry biomass versus standing dry body mass of various green algae and land plants) revealed that duckweeds are thus far the most rapidly growing angiosperms in proportion to their body mass. In light of this finding, we discuss the disposable soma and metabolic optimising theories, summarise evidence for and against the proposition that the Lemnoideae (family Araceae) reflect an example of reductive evolution, and argue that, under real-world conditions (environmental constraints and other limitations), 'Darwin-Wallace Demons' cannot exist, although the concept remains useful in much the same way that the Hardy-Weinberg law does. PMID:24674028

  13. CP violation and antigravity (revisited)

    Science.gov (United States)

    Chardin, G.

    1993-06-01

    Several arguments favour gravitation as the "Master Arrow of Time". Providing an explanation in terms of gravitation for the CP (and T) violation observed in the neutral kaon system, which provides the only example of a microscopic "arrow of time", is therefore extremely tempting. We show qualitatively that "antigravity" would provide just the amount of anomalous regeneration that we call CP violation and that a consequence of antigravity would be that any massive body would evaporate with the timescale of the Hawking radiation of black holes, which is linked to the generalized Second Law of Thermodynamics. Tests of this idea are proposed.

  14. Black hole formation by incoming electromagnetic radiation

    International Nuclear Information System (INIS)

    I revisit a known solution of the Einstein field equations to show that it describes the formation of non-spherical black holes by the collapse of pure electromagnetic monochromatic radiation. Both positive and negative masses are feasible without ever violating the dominant energy condition. The solution can also be used to model the destruction of naked singularities and the evaporation of white holes by emission or reception of light. (note)

  15. Coccolithophorids in polar waters: Pappomonas spp. revisited

    DEFF Research Database (Denmark)

    Thomsen, Helge Abildhauge; Østergaard, J.B.

    2014-01-01

    A contingent of weakly calcified coccolithophorid genera and species were described from polar regions almost 40 years ago. In the interim period a few additional findings have been reported enlarging the realm of some of the species. The genus Pappomonas is revisited here with the purpose of...... providing, based on additional sampling from both polar regions, an update on species morphology, life history aspects and biogeography that can serve as a reference for the future. The examination of a substantial number of cells unequivocally supports the elevation to species level of P. borealis stat...

  16. Sloan Digital Sky Survey Photometric Calibration Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  17. Conjure Revisited: Towards Automated Constraint Modelling

    CERN Document Server

    Akgun, Ozgur; Hnich, Brahim; Jefferson, Chris; Miguel, Ian

    2011-01-01

    Automating the constraint modelling process is one of the key challenges facing the constraints field, and one of the principal obstacles preventing widespread adoption of constraint solving. This paper focuses on the refinement-based approach to automated modelling, where a user specifies a problem in an abstract constraint specification language and it is then automatically refined into a constraint model. In particular, we revisit the Conjure system that first appeared in prototype form in 2005 and present a new implementation with a much greater coverage of the specification language Essence.

  18. Polynomial chaotic inflation in supergravity revisited

    Directory of Open Access Journals (Sweden)

    Kazunori Nakayama

    2014-10-01

    Full Text Available We revisit a polynomial chaotic inflation model in supergravity which we proposed soon after the Planck first data release. Recently some issues have been raised in Ref. [12], concerning the validity of our polynomial chaotic inflation model. We study the inflaton dynamics in detail, and confirm that the inflaton potential is very well approximated by a polynomial potential for the parameters of our interest in any practical sense, and in particular, the spectral index and the tensor-to-scalar ratio can be estimated by single-field approximation. This justifies our analysis of the polynomial chaotic inflation in supergravity.

  19. Sloan Digital Sky Survey Photometric Calibration Revisited

    Science.gov (United States)

    Marriner, J.

    2016-05-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  20. Persegrams of Compositional Models Revisited: conditional independence

    Czech Academy of Sciences Publication Activity Database

    Jiroušek, Radim

    Malaga: University Malaga, 2008 - (Magdalena, L.; Ojeda Aciego, M.; Verdegay, J.), s. 915-922 ISBN 978-84-612-3061-7. [12th International Conference on Information Processing and Management of Uncertianlty in Konowledge-based Systems . Malaga (ES), 22.06.2008-27.06.2008] R&D Projects: GA MŠk(CZ) 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : conditional independence * probability distribution * multidimensionality Subject RIV: IN - Informatics, Computer Science http://library.utia.cas.cz/separaty/2008/MTR/jirousek-persegrams of compositional models revisited conditional independence.pdf

  1. Re-visiting the Piper Alpha accident

    OpenAIRE

    Dykesteen, Mette Kahrs

    2013-01-01

    The main objective of this thesis has been to re-visit the Piper Alpha accident using the latest version of the FLACS simulation code. In 1988/89 simulations of the gas explosion in the C Module of Piper Alpha were performed by Jan Roar Bakke and Idar Storvik at Christian Michelsen Institute, in conjunction with the investigation after the accident. For these simulations the computer code FLACS was used [1, 2]. In this thesis, the same simulation cases have been looked into, and the results o...

  2. A common origin for woody Sonchus and five related genera in the Macaronesian islands: molecular evidence for extensive radiation.

    OpenAIRE

    Kim, S. C.; Crawford, D J; Francisco-Ortega, J.; Santos-Guerra, A.

    1996-01-01

    Woody Sonchus and five related genera (Babcockia, Taeckholmia, Sventenia, Lactucosonchus, and Prenanthes) of the Macaronesian islands have been regarded as an outstanding example of adaptive radiation in angiosperms. Internal transcribed spacer region of the nuclear rDNA (ITS) sequences were used to demonstrate that, despite the extensive morphological and ecological diversity of the plants, the entire alliance in insular Macaronesia has a common origin. The sequence data place Lactucosonchus...

  3. Noncommutative information is revealed from Hawking radiation as tunneling

    OpenAIRE

    Zhang, Baocheng; Cai, Qing-yu; Zhan, Ming-sheng; You, Li

    2013-01-01

    We revisit the tunneling process from a Schwarzschild black hole in the noncommutative spacetime and obtain the non-thermal tunneling probability. In such non-thermal spectrum, the correlations are discovered, which can carry the information about the noncommutativity. Thus this enlightens a way to find the noncommutative information in the Hawking radiation. The entropy is also shown to be conserved in the whole radiation process, which implies that the unitarity is held even for the Hawking...

  4. Influences of evergreen gymnosperm and deciduous angiosperm tree species on the functioning of temperate and boreal forests.

    Science.gov (United States)

    Augusto, Laurent; De Schrijver, An; Vesterdal, Lars; Smolander, Aino; Prescott, Cindy; Ranger, Jacques

    2015-05-01

    It has been recognized for a long time that the overstorey composition of a forest partly determines its biological and physical-chemical functioning. Here, we review evidence of the influence of evergreen gymnosperm (EG) tree species and deciduous angiosperm (DA) tree species on the water balance, physical-chemical soil properties and biogeochemical cycling of carbon and nutrients. We used scientific publications based on experimental designs where all species grew on the same parent material and initial soil, and were similar in stage of stand development, former land use and current management. We present the current state of the art, define knowledge gaps, and briefly discuss how selection of tree species can be used to mitigate pollution or enhance accumulation of stable organic carbon in the soil. The presence of EGs generally induces a lower rate of precipitation input into the soil than DAs, resulting in drier soil conditions and lower water discharge. Soil temperature is generally not different, or slightly lower, under an EG canopy compared to a DA canopy. Chemical properties, such as soil pH, can also be significantly modified by taxonomic groups of tree species. Biomass production is usually similar or lower in DA stands than in stands of EGs. Aboveground production of dead organic matter appears to be of the same order of magnitude between tree species groups growing on the same site. Some DAs induce more rapid decomposition of litter than EGs because of the chemical properties of their tissues, higher soil moisture and favourable conditions for earthworms. Forest floors consequently tend to be thicker in EG forests compared to DA forests. Many factors, such as litter lignin content, influence litter decomposition and it is difficult to identify specific litter-quality parameters that distinguish litter decomposition rates of EGs from DAs. Although it has been suggested that DAs can result in higher accumulation of soil carbon stocks, evidence from

  5. The isotropic radio background revisited

    CERN Document Server

    Fornengo, Nicolao; Regis, Marco; Taoso, Marco

    2014-01-01

    We present an extensive analysis on the determination of the isotropic radio background. We consider six different radio maps, ranging from 22 MHz to 2.3 GHz and covering a large fraction of the sky. The large scale emission is modeled as a linear combination of an isotropic component plus the Galactic synchrotron radiation and thermal bremsstrahlung. Point-like and extended sources are either masked or accounted for by means of a template. We find a robust estimate of the isotropic radio background, with limited scatter among different Galactic models. The level of the isotropic background lies significantly above the contribution obtained by integrating the number counts of observed extragalactic sources. Since the isotropic component dominates at high latitudes, thus making the profile of the total emission flat, a Galactic origin for such excess appears unlikely. We conclude that, unless a systematic offset is present in the maps, and provided that our current understanding of the Galactic synchrotron emi...

  6. The role of brand destination experience in determining revisit intention

    DEFF Research Database (Denmark)

    Mattsson, Jan; Barnes, Stuart; Sørensen, Flemming

    experience, which provides a more holistic and unified view of the brand destination. The research uses a logistic regression model to determine the role of satisfaction and brand experience in determining revisit intentions. The study also examines differences among subgroups and four brand experience sub......-constructs. The findings suggest that brand experience is an important determinant of revisit intentions, but that there is variation among respondent groups. The paper rounds off with conclusions and implications for research and practice....

  7. Ground Zero revisits shape outbreaks: Zika and beyond

    CERN Document Server

    Manrique, Pedro D; Johnson, Neil F

    2016-01-01

    During an infection outbreak, many people continue to revisit Ground Zero - such as the one square mile of Miami involved in the current Zika outbreak- for work, family or social reasons. Public health planning must account for the counterintuitive ways in which this human flow affects the outbreak's duration, severity and time-to-peak. Managing this flow of revisits can allow the outbreak's evolution to be tailored.

  8. Ornithogalum virens as a plant assay for beta and gamma radiation effects

    International Nuclear Information System (INIS)

    The purpose of this study was to determine if the monocotyledonous angiosperm, Ornithogalum virens (Quintanilha and Cabral, 1947), could be used in such a biological assay system. After exposing O. virens plants to acute (60Co) and chronic (137Cs) gamma radiation and internal beta radiation (32P), lethality (LD50, LD100), growth inhibition, and chromosome aberrations were investigated. The LD50 and LD100 for acute gamma radiation were estimated to be between 0.91 to 1.8 krad and less than 3.6 krad, respectively. Though growth inhibition and abnormal growth were observed in the acute and chronic gamma radiation studies, the changes in the growth of the plants were so variable that these parameters were found to be unreliable measures of radiation effects. Chromosome aberrations were a more reliable measure of radiation damage because linear relationships between total aberrations and dose were found for both gamma and beta radiation

  9. A revisited standard solar model

    International Nuclear Information System (INIS)

    Recent models of the Sun, including our own, based on canonical physics and featuring modern reaction rates and radiative opacities are presented. They lead to a presolar helium abundance of approximately 0.28 by mass, at variance with the value of 0.25 proposed by Bahcall et al. (1982, 1985), but in better agreement with the value found in the Orion nebula. Most models predict a neutrino counting rate greater than 6 SNU in the chlorine-argon detector, which is at least 3 times higher than the observed rate. The primordial helium abundance derived from the solar one, on the basis of recent models of helium production from the birth of the Galaxy to the birth of the sun, Ysub(P) approximately 0.26, is significantly higher than the value inferred from observations of extragalactic metal-poor nebulae (Y approximately 0.23). This indicates that the stellar production of helium is probably underestimated by the models considered

  10. Newton's law of cooling revisited

    International Nuclear Information System (INIS)

    The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer from any object to its surrounding is not only due to conduction and convection but also due to radiation. The latter does not vary linearly with temperature difference, which leads to deviations from Newton's law. This paper presents a theoretical analysis of the cooling of objects with a small Biot number. It is shown that Newton's law of cooling, i.e. simple exponential behaviour, is mostly valid if temperature differences are below a certain threshold which depends on the experimental conditions. For any larger temperature differences appreciable deviations occur which need the complete nonlinear treatment. This is demonstrated by results of some laboratory experiments which use IR imaging to measure surface temperatures of solid cooling objects with temperature differences of up to 300 K.

  11. Molecular phylogeny and radiation time of erysiphales inferred from the nuclear ribosomal DNA sequences

    International Nuclear Information System (INIS)

    Phylogenetic relationships of Erysiphales within Ascomycota were inferred from the newly determined sequences of the 18S rDNA and partial sequences of the 28S rDNA including the D1 and D2 regions of 10 Erysiphales taxa. Phylogenetic analyses revealed that the Erysiphales form a distinct clade among ascomycetous fungi suggesting that the Erysiphales diverged from a single ancestral taxon. The Myxotrichaceae of the Onygenales was distantly related to the other onygenalean families and was the sister group to the Erysiphales calde, with which it combined to form a clade. The Erysiphales/Myxotrichaceae clade was also closely related to some discomycetous fungi (Leotiales, Cyttariales and Thelebolaceae) including taxa that form cleistothecial ascomata. The present molecular analyses as well as previously reported morphological observations suggest the possible existence of a novel evolutionary pathway from cleistothecial discomycetous fungi to Erysiphales and Myxotrichaceae. However, since most of these fungi, except for the Erysiphales, are saprophytic on dung and/or plant materials, the questions of how and why an obligate biotroph like the Erysiphales radiated from the saprophytic fungi remain to be addressed. We also estimated the radiation time of the Erysiphales using the 18S rDNA sequences and the two molecular clockes that have been previously reported. The calculation showed that the Erysiphales split from the Myxotrichaceae 190–127 myr ago. Since the radiation time of the Erysiphales does not exceed 230 myr ago, even when allowance is made for the uncertainty of the molecular clocks, it is possible to consider that the Erysiphales evolved after the radiation of angiosperms. The results of our calculation also showed that the first radiation within the Erysiphales (138–92 myr ago) coincided with the date of a major diversification of angiosperms (130–90 myr ago). These results may support our early assumption that the radiation of the Erysiphales

  12. Copper doped borate dosimeters revisited

    International Nuclear Information System (INIS)

    We render a panoramic overview on copper (Cu) doped borate dosimeters. Preparing a dosimeter by mixing specific materials with precise weights and methods is a never-ending quest. The recommended composition is highly decisive for accurate estimation of the absorbed dose, prediction of the biological outcome, determination of the treatment dose for radiation therapy and facilitation of personal monitoring. Based on these principles, the proposed dosimeter must cover a series of dosimetric properties to realize the exact results and assessment. The doped borate dosimeters indeed demonstrate attractive thermoluminescence (TL) features. Several dedicated efforts are attempted to improve the luminescence properties by doping various transition metals or rare-earth elements. The Cu ion being one of the preferred activators shows excellent TL properties as revealed via detail comparison with other dosimeters. Two oxide states of Cu (Cu+ and Cu++) with reasonable atomic number allow easy interaction with boron network. Interestingly, the intrinsic luminescent centers of borate lattice are in cross linked with that of Cu+ ions. Thus, the activation of borate dosimeter with Cu ions for the enhancement of the TL sensitivity is recognized. These dosimeters reveal similar glow curves as the standard TLD-100 (LiF:Mg,Ti) one irrespective of the use of modifiers and synthesis techniques. They display high sensitivity, low fading, dose response linearity over wide range and practical minimum detectable dose. Furthermore, the effective atomic number being the most beneficial aspect (equivalent to that of human tissue) of borate dosimeters do not show any change due to Cu ion activations. The past development, major challenges, excitement, applications, recent progress and the future promises of Cu doped borate TL dosimeters are highlighted. - Highlights: • The manuscript gives a panoramic overview on copper doped borate dosimeters. • Cu ions activated technique in borate

  13. Copper doped borate dosimeters revisited

    Energy Technology Data Exchange (ETDEWEB)

    Alajerami, Y.S.M. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Department of Medical Radiography, Al-Azhar University, Gaza Strip, Palestine (Country Unknown); Hashim, S., E-mail: suhairul@utm.my [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Oncology Treatment Centre, Sultan Ismail Hospital, 81100 Johor Bahru (Malaysia); Ghoshal, S.K. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Bradley, D.A. [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Mhareb, M. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Saleh, M.A. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); National Atomic Energy Commission (NATEC), Sana' a (Yemen)

    2014-11-15

    We render a panoramic overview on copper (Cu) doped borate dosimeters. Preparing a dosimeter by mixing specific materials with precise weights and methods is a never-ending quest. The recommended composition is highly decisive for accurate estimation of the absorbed dose, prediction of the biological outcome, determination of the treatment dose for radiation therapy and facilitation of personal monitoring. Based on these principles, the proposed dosimeter must cover a series of dosimetric properties to realize the exact results and assessment. The doped borate dosimeters indeed demonstrate attractive thermoluminescence (TL) features. Several dedicated efforts are attempted to improve the luminescence properties by doping various transition metals or rare-earth elements. The Cu ion being one of the preferred activators shows excellent TL properties as revealed via detail comparison with other dosimeters. Two oxide states of Cu (Cu{sup +} and Cu{sup ++}) with reasonable atomic number allow easy interaction with boron network. Interestingly, the intrinsic luminescent centers of borate lattice are in cross linked with that of Cu{sup +} ions. Thus, the activation of borate dosimeter with Cu ions for the enhancement of the TL sensitivity is recognized. These dosimeters reveal similar glow curves as the standard TLD-100 (LiF:Mg,Ti) one irrespective of the use of modifiers and synthesis techniques. They display high sensitivity, low fading, dose response linearity over wide range and practical minimum detectable dose. Furthermore, the effective atomic number being the most beneficial aspect (equivalent to that of human tissue) of borate dosimeters do not show any change due to Cu ion activations. The past development, major challenges, excitement, applications, recent progress and the future promises of Cu doped borate TL dosimeters are highlighted. - Highlights: • The manuscript gives a panoramic overview on copper doped borate dosimeters. • Cu ions activated

  14. Evolution of plant phage-type RNA polymerases: the genome of the basal angiosperm Nuphar advena encodes two mitochondrial and one plastid phage-type RNA polymerases

    Directory of Open Access Journals (Sweden)

    Börner Thomas

    2010-12-01

    Full Text Available Abstract Background In mono- and eudicotyledonous plants, a small nuclear gene family (RpoT, RNA polymerase of the T3/T7 type encodes mitochondrial as well as chloroplast RNA polymerases homologous to the T-odd bacteriophage enzymes. RpoT genes from angiosperms are well characterized, whereas data from deeper branching plant species are limited to the moss Physcomitrella and the spikemoss Selaginella. To further elucidate the molecular evolution of the RpoT polymerases in the plant kingdom and to get more insight into the potential importance of having more than one phage-type RNA polymerase (RNAP available, we searched for the respective genes in the basal angiosperm Nuphar advena. Results By screening a set of BAC library filters, three RpoT genes were identified. Both genomic gene sequences and full-length cDNAs were determined. The NaRpoT mRNAs specify putative polypeptides of 996, 990 and 985 amino acids, respectively. All three genes comprise 19 exons and 18 introns, conserved in their positions with those known from RpoT genes of other land plants. The encoded proteins show a high degree of conservation at the amino acid sequence level, including all functional crucial regions and residues known from the phage T7 RNAP. The N-terminal transit peptides of two of the encoded polymerases, NaRpoTm1 and NaRpoTm2, conferred targeting of green fluorescent protein (GFP exclusively to mitochondria, whereas the third polymerase, NaRpoTp, was targeted to chloroplasts. Remarkably, translation of NaRpoTp mRNA has to be initiated at a CUG codon to generate a functional plastid transit peptide. Thus, besides AGAMOUS in Arabidopsis and the Nicotiana RpoTp gene, N. advena RpoTp provides another example for a plant mRNA that is exclusively translated from a non-AUG codon. In contrast to the RpoT of the lycophyte Selaginella and those of the moss Physcomitrella, which are according to phylogenetic analyses in sister positions to all other phage

  15. Flavonoids can protect maize DNA from the induction of ultraviolet radiation damage

    International Nuclear Information System (INIS)

    Diverse flavonoid compounds are widely distributed in angiosperm families. Flavonoids absorb radiation in the ultraviolet (UV) region of the spectrum, and it has been proposed that these compounds function as UV filters. We demonstrate that the DNA in Zea mays plants that contain flavonoids (primarily anthocyanins) is protected from the induction of damage caused by UV radiation relative to the DNA in plants that are genetically deficient in these compounds. DNA damage was measured with a sensitive and simple assay using individual monoclonal antibodies, one specific for cyclobutane pyrimidine dimer damage and the other specific for pyrimidine(6,4)pyrimidone damage. (author)

  16. The Faraday effect revisited: General theory

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

    2006-01-01

    the Fermi energy lies in a spectral gap, we rigorously prove theWidom-Streda formula. For free electrons, the transverse conductivity can be explicitly computed and coincides with the classical result. In the general case, using magnetic perturbation theory, the conductivity tensor is expanded in......This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. At zero temperature and zero frequency, if...... field Bloch functions and energies. No derivatives with respect to the quasimomentum appear and thereby all ambiguities are removed, in contrast to earlier work....

  17. The Faraday effect revisited: General theory

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Nenciu, Gheorghe; Pedersen, Thomas Garm

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse...... conductivity can be explicitly computed and coincides with the classical result. In the general case, using magnetic perturbation theory, the conductivity tensor is expanded in powers of the strength of the magnetic field B. Then the linear term in B of this expansion is written down in terms of the zero...... magnetic field Green function and the zero field current operator. In the periodic case, the linear term in B of the conductivity tensor is expressed in terms of zero magnetic field Bloch functions and energies. No derivatives with respect to the quasimomentum appear and thereby all ambiguities are removed...

  18. Visser's Massive Gravity Bimetric Theory Revisited

    CERN Document Server

    de Roany, Alain; Pacheco, J A de Freitas

    2011-01-01

    A massive gravity theory was proposed by Visser in the late nineties. This theory, based on a backgroung metric $b_{\\alpha \\beta}$ and on an usual dynamical metric $g_{\\alpha \\beta}$ has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with a particular care on the related conservation laws.\\ It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a non-static background metric is required in order to obtain a solution able to mimic the $\\Lambda$CDM cosmology.

  19. The Faraday effect revisited General theory

    CERN Document Server

    Cornean, H D; Pedersen, T G

    2005-01-01

    This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. For free electrons, the transverse conductivity can be explicitly computed and coincides with the classical result. In the general case, using magnetic perturbation theory, the conductivity tensor is expanded in powers of the strength of the magnetic field $B$. Then the linear term in $B$ of this expansion is written down in terms of the zero magnetic field Green function and the zero field current operator. In the periodic case, the linear term in $B$ of the conductivity tensor is expressed in terms of zero magnetic field Bloch functions and energies. No derivatives with respect to the quasimomentum appear and thereby all ambiguities are removed, in contrast to earlier work.

  20. Three dimensional maximally supersymmetric field theory revisited

    International Nuclear Information System (INIS)

    The field theoretical realization of maximally extended supersymmetry algebra in 3 dimensions is revisited here. The existence of an interacting field theory which also manifests the full automorphism demands the existence of extra global symmetry transformations. They form the infinite-dimensional group of volume-preserving diffeomorphisms of an internal 3-dimensional space. Upon regularization, it will be truncated to a finite-dimensional unitary group. This extra symmetry together with multiplicity of component fields allow one to consistently introduce self-interactions through Nambu brackets or matrix 4-commutators. It turns out that there exists a conformal field theory which is invariant under OSp(4 | 8) x U(N) groups of global transformations. Relaxing full automorphism to its biggest subgroup, one can consistently mass-deforms the theory. In addition to ordinary associative algebraic structures, a non-associative structure also underlies this theory. (author)

  1. Sparse random matrices: The eigenvalue spectrum revisited

    International Nuclear Information System (INIS)

    We revisit the derivation of the density of states of sparse random matrices. We derive a recursion relation that allows one to compute the spectrum of the matrix of incidence for finite trees that determines completely the low concentration limit. Using the iterative scheme introduced by Biroli and Monasson [J. Phys. A 32, L255 (1999)] we find an approximate expression for the density of states expected to hold exactly in the opposite limit of large but finite concentration. The combination of the two methods yields a very simple geometric interpretation of the tails of the spectrum. We test the analytic results with numerical simulations and we suggest an indirect numerical method to explore the tails of the spectrum. (author)

  2. Revisiting light neutralino scenarios in the MSSM

    CERN Document Server

    Vasquez, Daniel Albornoz; Boehm, Celine

    2011-01-01

    We revisit the case of a light neutralino LSP in the framework of the MSSM. We consider a model with eleven free parameters. We show that all scenarios where the annihilation of light neutralinos rely mainly on the exchange of a light pseudoscalar are excluded by direct detection searches and by Fermi measurements of the gamma-flux from dwarf spheroidal galaxies. On the other hand, we find scenarios with light sleptons that satisfy all collider and astroparticle physics constraints. In this case, the lower limit on the LSP mass is 12.6 GeV. We discuss how the parameter space of the model will be further probed by new physics searches at the LHC.

  3. Revisiting monotop production at the LHC

    CERN Document Server

    Boucheneb, Idir; Deandrea, Aldo; Fuks, Benjamin

    2015-01-01

    Scenarios of new physics where a single top quark can be produced in association with large missing energy (monotop) have been recently studied both from the theoretical point of view and by experimental collaborations. We revisit the originally proposed monotop setup by embedding the effective couplings of the top quark in an SU(2)L invariant formalism. We show that minimality selects one model for each of the possible production mechanisms: a scalar field coupling to a right-handed top quark and an invisible fermion when the monotop system is resonantly produced, and a vector field mediating the interactions of a dark sector to right-handed quarks for the non-resonant production mode. We study in detail constraints on the second class of scenarios, originating from contributions to standard single top processes when the mediator is lighter than the top quark and from the dark matter relic abundance when the mediator is heavier than the top quark.

  4. The Species Problem in Myxomycetes Revisited.

    Science.gov (United States)

    Walker, Laura M; Stephenson, Steven L

    2016-08-01

    Species identification in the myxomycetes (plasmodial slime molds or myxogastrids) poses particular challenges to researchers as a result of their morphological plasticity and frequent alteration between sexual and asexual life strategies. Traditionally, myxomycete morphology has been used as the primary method of species delimitation. However, with the increasing availability of genetic information, traditional myxomycete taxonomy is being increasingly challenged, and new hypotheses continue to emerge. Due to conflicts that sometimes occur between traditional and more modern species concepts that are based largely on molecular data, there is a pressing need to revisit the discussion surrounding the species concept used for myxomycetes. Biological diversity is being increasingly studied with molecular methods and data accumulates at ever-faster rates, making resolution of this matter urgent. In this review, currently used and potentially useful species concepts (biological, morphological, phylogenetic and ecological) are reviewed, and an integrated approach to resolve the myxomycete species problem is discussed. PMID:27351595

  5. Revisiting instanton corrections to the Konishi multiplet

    CERN Document Server

    Alday, Luis F

    2016-01-01

    We revisit the calculation of instanton effects in correlation functions in ${\\cal N}=4$ SYM involving the Konishi operator and operators of twist two. Previous studies revealed that the scaling dimensions and the OPE coefficients of these operators do not receive instanton corrections in the semiclassical approximation. We go beyond this approximation and demonstrate that, while operators belonging to the same ${\\cal N}=4$ supermultiplet ought to have the same conformal data, the evaluation of quantum instanton corrections for one operator can be mapped into a semiclassical computation for another operator in the same supermultiplet. This observation allows us to compute explicitly the leading instanton correction to the scaling dimension of operators in the Konishi supermultiplet as well as to their structure constants in the OPE of two half-BPS scalar operators. We then use these results, together with crossing symmetry, to determine instanton corrections to scaling dimensions of twist-four operators with ...

  6. Revisiting Weak Simulation for Substochastic Markov Chains

    DEFF Research Database (Denmark)

    Jansen, David N.; Song, Lei; Zhang, Lijun

    2013-01-01

    The spectrum of branching-time relations for probabilistic systems has been investigated thoroughly by Baier, Hermanns, Katoen and Wolf (2003, 2005), including weak simulation for systems involving substochastic distributions. Weak simulation was proven to be sound w.r.t. the liveness fragment...... of the logic PCTL\\x, and its completeness was conjectured. We revisit this result and show that soundness does not hold in general, but only for Markov chains without divergence. It is refuted for some systems with substochastic distributions. Moreover, we provide a counterexample to completeness....... In this paper, we present a novel definition that is sound for live PCTL\\x, and a variant that is both sound and complete. A long version of this article containing full proofs is available from [11]....

  7. Seasonal dating of Sappho's 'Midnight Poem' revisited

    Science.gov (United States)

    Cuntz, Manfred; Gurdemir, Levent; George, Martin

    2016-04-01

    Sappho was a Greek lyric poet who composed a significant array of pristine poetry. Although much of it has been lost, her reputation has endured thanks to numerous surviving fragments. One of her contributions includes the so-called 'Midnight Poem', which contains a line about the Pleiades, setting sometime before midnight, and supposedly observed from the island of Lesbos. This poem also refers to the setting of the Moon. Sappho's Midnight Poem thus represents a prime example of where ancient poetry and astronomy merge, and it also offers the possibility of seasonal dating. Previously, Herschberg and Mebius (1990) estimated that the poem was composed in late winter/early spring, a time frame that is not unusual for lyrics of an amorous nature. The aim of our paper is to revisit this earlier finding by using modern-day software. Our study confirms Herschberg and Mebius' result, but also conveys further information.

  8. Neutrino dark energy. Revisiting the stability issue

    International Nuclear Information System (INIS)

    A coupling between a light scalar field and neutrinos has been widely discussed as a mechanism for linking (time varying) neutrino masses and the present energy density and equation of state of dark energy. However, it has been pointed out that the viability of this scenario in the non-relativistic neutrino regime is threatened by the strong growth of hydrodynamic perturbations associated with a negative adiabatic sound speed squared. In this paper we revisit the stability issue in the framework of linear perturbation theory in a model independent way. The criterion for the stability of a model is translated into a constraint on the scalar-neutrino coupling, which depends on the ratio of the energy densities in neutrinos and cold dark matter. We illustrate our results by providing meaningful examples both for stable and unstable models. (orig.)

  9. Revisiting Lepton Flavour Universality in B Decays

    CERN Document Server

    Feruglio, Ferruccio; Pattori, Andrea

    2016-01-01

    Lepton flavour universality (LFU) in B-decays is revisited in a model-independent way by considering semileptonic operators defined at a scale Lambda above the electroweak scale v. The importance of quantum effects, so far neglected in the literature, is emphasised. We construct the low-energy effective Lagrangian taking into account the running effects from Lambda down to v through the one-loop renormalization group equations (RGE) in the limit of exact electroweak symmetry and QED RGEs from v down to the 1 GeV scale. The most important quantum effects turn out to be the modification of the leptonic couplings of the vector boson Z and the generation of a purely leptonic effective Lagrangian. Large LFU breaking effects in Z and tau decays and visible lepton flavour violating (LFV) effects in the processes tau -> mu ll, tau -> mu rho, tau -> mu pi and tau -> mu eta^(') are induced.

  10. Resolution of Reflection Seismic Data Revisited

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Mosegaard, Klaus; Zunino, Andrea

    lower vertical resolution of reflection seismic data. In the following we will revisit think layer model and demonstrate that there is in practice no limit to the vertical resolution using the parameterization of Widess (1973), and that the vertical resolution is limited by the noise in the data. In......The Rayleigh Principle states that the minimum separation between two reflectors that allows them to be visually separated is the separation where the wavelet maxima from the two superimposed reflections combine into one maximum. This happens around Δtres = λb/8, where λb is the predominant...... general, we discuss that the resolution of reflection seismic data is controlled by the noise level and the a priori information available...

  11. Both water source and atmospheric water impact leaf wax n-alkane 2H/1H values of hydroponically grown angiosperm trees

    Science.gov (United States)

    Tipple, B. J.; Berke, M. A.; Hambach, B.; Roden, J. S.; Ehleringer, J. R.

    2013-12-01

    The extent to which both water source and leaf water 2H-enrichment affect the δ2H values of terrestrial plant leaf waxes is an area of active research as ecologists seek a mechanistic understanding of the environmental determinants of leaf wax isotope values before applying δ2H values of leaf waxes to reconstruct past hydrologic conditions. To elucidate the effects of both water source and atmospheric water vapor on δ2H values of leaf waxes for broad-leaved angiosperms, we analyzed hydrogen isotope ratios of high-molecular weight n-alkanes from two tree species that were grown throughout the spring and summer (five months) in a hydroponic system under controlled atmospheric conditions. Here, 12 subpopulations each of Populus fremontii and Betula occidentalis saplings were grown under one of six source different waters ranging in hydrogen isotope ratio values from -120 to +180 ‰ and under either 40 % or 75 % relative humidity conditions. We found n-alkane δ2H values of both species were linearly related to source water δ2H values with differences in slope associated with differing atmospheric humidity. A Craig-Gordon model was used to predict the δ2H values of leaf water and, by extension, n-alkane δ2H values under the range of growth conditions. The modeled leaf water values were found to be linearly related to observed n-alkane δ2H values with a statistically indistinguishable slope between the high and low humidity treatments. These leaf wax observations support a constant biosynthetic fractionation factor between evaporatively-enriched leaf water and n-alkanes for each species. However, we found the calculated biosynthetic fractionation between modeled leaf-water and n-alkane to be different between the two species. We submit that these dissimilarities were due to model inputs and not differences in the specific-species biochemistry. Nonetheless, these results are significant as they indicated that the δ2H value of atmospheric water vapor and

  12. Charge symmetry breaking in $\\Lambda$ hypernuclei revisited

    CERN Document Server

    Gal, Avraham

    2015-01-01

    The large charge symmetry breaking (CSB) implied by the $\\Lambda$ binding energy difference $\\Delta B^{4}_{\\Lambda}(0^+_{\\rm g.s.})\\equiv B_{\\Lambda}(_{\\Lambda}^4$He)$-$$B_{\\Lambda}(_{\\Lambda}^4$H) = 0.35$\\pm$0.06 MeV of the $A=4$ mirror hypernuclei ground states, determined from emulsion studies, has defied theoretical attempts to reproduce it in terms of CSB in hyperon masses and in hyperon-nucleon interactions, including one pion exchange arising from $\\Lambda-\\Sigma^0$ mixing. Using a schematic strong-interaction $\\Lambda N\\leftrightarrow\\Sigma N$ coupling model developed by Akaishi and collaborators for $s$-shell $\\Lambda$ hypernuclei, we revisit the evaluation of CSB in the $A=4$ $\\Lambda$ hypernuclei and extend it to $p$-shell mirror $\\Lambda$ hypernuclei. The model yields values of $\\Delta B^{4}_{\\Lambda} (0^+_{\\rm g.s.})\\sim 0.25$ MeV. Smaller size and mostly negative $p$-shell binding energy differences are calculated for the $A=7-10$ mirror hypernuclei, in rough agreement with the few available dat...

  13. Revisiting Twomey's approximation for peak supersaturation

    Directory of Open Access Journals (Sweden)

    B. J. Shipway

    2015-04-01

    Full Text Available Twomey's seminal 1959 paper provided lower and upper bound approximations to the estimation of peak supersaturation within an updraft and thus provides the first closed expression for the number of nucleated cloud droplets. The form of this approximation is simple, but provides a surprisingly good estimate and has subsequently been employed in more sophisticated treatments of nucleation parametrization. In the current paper, we revisit the lower bound approximation of Twomey and make a small adjustment that can be used to obtain a more accurate calculation of peak supersaturation under all potential aerosol loadings and thermodynamic conditions. In order to make full use of this improved approximation, the underlying integro-differential equation for supersaturation evolution and the condition for calculating peak supersaturation are examined. A simple rearrangement of the algebra allows for an expression to be written down that can then be solved with a single lookup table with only one independent variable for an underlying lognormal aerosol population. While multimodal aerosol with N different dispersion characteristics requires 2N+1 inputs to calculate the activation fraction, only N of these one-dimensional lookup tables are needed. No additional information is required in the lookup table to deal with additional chemical, physical or thermodynamic properties. The resulting implementation provides a relatively simple, yet computationally cheap, physically based parametrization of droplet nucleation for use in climate and Numerical Weather Prediction models.

  14. No-scale ripple inflation revisited

    International Nuclear Information System (INIS)

    We revisit the no-scale ripple inflation model, where no-scale supergravity is modified by an additional term for the inflaton field in the Kähler potential. This term not only breaks one SU(N,1) symmetry explicitly, but also plays an important role for inflation. We generalize the superpotential in the no-scale ripple inflation model slightly. There exists a discrete Z2 symmetry/parity in the scalar potential in general, which can be preserved or violated by the non-canonical nomalized inflaton kinetic term. Thus, there are three inflation paths: one parity invariant path, and the left and right paths for parity violating scenario. We show that the inflations along the parity invariant path and right path are consistent with the Planck results. However, the gavitino mass for the parity invariant path is so large that the inflation results will be invalid if we consider the inflaton supersymmetry breaking soft mass term. Thus, only the inflation along the right path gives the correct and consistent results. Notably, the tensor-to-scalar ratio in such case can be large, with a value around 0.05, which may be probed by the future Planck experiment

  15. Spin-orbit evolution of Mercury revisited

    CERN Document Server

    Noyelles, Benoit; Makarov, Valeri; Efroimsky, Michael

    2013-01-01

    Mercury is a peculiar case, in that it is locked into the 3:2 spin-orbit resonance. Its rotation period, 58 days, is exactly two thirds of its orbital period. It is accepted that the eccentricity of Mercury (0.206) favours the trapping into this resonance. More controversial is how the capture took place. A recent study by Makarov has shown that entrapment into this resonance is certain if the eccentricity is larger than 0.2, provided that we use a realistic tidal model, based on the Darwin-Kaula expansion of the tidal torque, including both the elastic rebound and anelastic creep of solids. We here revisit the scenario of Mercury's capture into the supersynchronous spin-orbit resonances. The study is based on a realistic model of tidal friction in solids, that takes into account the rheology and the self-gravitation of the planet. Developed in Efroimsky, it was employed by Makarov et al. to determine the likely spin state of the planet GJ581d, with its eccentricity evolution taken into account. It was also u...

  16. Targeting Cancer Metabolism - Revisiting the Warburg Effects.

    Science.gov (United States)

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-07-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  17. ANAL FISSURE REVISITED : A SYSTEMATIC REVIEW

    Directory of Open Access Journals (Sweden)

    Manju

    2015-07-01

    Full Text Available Anal fissure is one of the most common anorectal problems. Anal fissure is largely associated with high anal sphincter pressures and most treatment options are based on reducing anal pressures. There are many options to treat chronic fissures in ano. Some of them are non - surgical while the others are su rgical. The efficacy claimed by each of the prevalent method is very high but the inconsistencies and contraindications are equally strong. To date, lateral sphincterotomy has been favoured by most of the proctologists, because it is the least extensive su rgical procedure and is offering a long lasting relief in sphincter spasm. Various management technique are reviewed in this article along with Advancement flap for anterior fissure and a new method combining the age - old technique of Lord's manual dilatati on followed by radio surgery is also highlighted along with their complications. The addition of radio surgery is found useful for refreshing the edges of the fissure and to tackle pathologies namely sentinel pile, small internal piles or hypertrophied ana l papillae often found associated with chronic fissures. Revisiting the trends of treatment of chronic anal fissures, the most preferred options are the manual dilatation with radio surgery and the subcutaneous lateral anal sphincterotomy. Both methods are easy to perform, have negligible complications and no special setup is needed, except the radio surgical unit, in case of the first procedure.

  18. Revisiting the argument from fetal potential

    Directory of Open Access Journals (Sweden)

    Manninen Bertha

    2007-05-01

    Full Text Available Abstract One of the most famous, and most derided, arguments against the morality of abortion is the argument from potential, which maintains that the fetus' potential to become a person and enjoy the valuable life common to persons, entails that its destruction is prima facie morally impermissible. In this paper, I will revisit and offer a defense of the argument from potential. First, I will criticize the classical arguments proffered against the importance of fetal potential, specifically the arguments put forth by philosophers Peter Singer and David Boonin, by carefully unpacking the claims made in these arguments and illustrating why they are flawed. Secondly, I will maintain that fetal potential is morally relevant when it comes to the morality of abortion, but that it must be accorded a proper place in the argument. This proper place, however, cannot be found until we first answer a very important and complex question: we must first address the issue of personal identity, and when the fetus becomes the type of being who is relevantly identical to a future person. I will illustrate why the question of fetal potential can only be meaningfully addressed after we have first answered the question of personal identity and how it relates to the human fetus.

  19. Revisiting the relaxation dynamics of isolated pyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Montero, Raúl; Ovejas, Virginia; Fernández-Fernández, Marta; Longarte, Asier, E-mail: asier.longarte@ehu.es [Departamento de Química Física, Universidad del País Vasco (UPV/EHU), Apart. 644, 48080 Bilbao (Spain); Peralta Conde, Álvaro [Centro de Láseres Pulsados (CLPU), Edificio M3, Parque Científico, 37185 Villamayor (Spain)

    2014-07-07

    Herein, the interpretation of the femtosecond-scale temporal evolution of the pyrrole ion signal, after excitation in the 267–217 nm interval, recently published by our group [R. Montero, A. Peralta Conde, V. Ovejas, M. Fernández-Fernández, F. Castaño, J. R. Vázquez de Aldana, and A. Longarte, J. Chem. Phys.137, 064317 (2012)] is re-visited. The observation of a shift in the pyrrole{sup +} transient respect to zero delay reference, initially attributed to ultrafast dynamics on the πσ{sup *} type state (3s a{sub 1} ← π 1a{sub 2}), is demonstrated to be caused by the existence of pump + probe populated states, along the ionization process. The influence of these resonances in pump-prone ionization experiments, when multi-photon probes are used, and the significance of a proper zero-time reference, is discussed. The possibility of preparing the πσ{sup *} state by direct excitation is investigated by collecting 1 + 1 photoelectron spectra, at excitation wavelengths ranging from 255 to 219 nm. No conclusive evidences of ionization through this state are found.

  20. The Super-GUT CMSSM Revisited

    CERN Document Server

    Ellis, John; Mustafayev, Azar; Nagata, Natsumi; Olive, Keith A

    2016-01-01

    We revisit minimal supersymmetric SU(5) grand unification (GUT) models in which the soft supersymmetry-breaking parameters of the minimal supersymmetric Standard Model (MSSM) are universal at some input scale, $M_{in}$, above the supersymmetric gauge coupling unification scale, $M_{GUT}$. As in the constrained MSSM (CMSSM), we assume that the scalar masses and gaugino masses have common values, $m_0$ and $m_{1/2}$ respectively, at $M_{in}$, as do the trilinear soft supersymmetry-breaking parameters $A_0$. Going beyond previous studies of such a super-GUT CMSSM scenario, we explore the constraints imposed by the lower limit on the proton lifetime and the LHC measurement of the Higgs mass, $m_h$. We find regions of $m_0$, $m_{1/2}$, $A_0$ and the parameters of the SU(5) superpotential that are compatible with these and other phenomenological constraints such as the density of cold dark matter, which we assume to be provided by the lightest neutralino. Typically, these allowed regions appear for $m_0$ and $m_{1/...

  1. Revisiting Twomey's approximation for peak supersaturation

    Directory of Open Access Journals (Sweden)

    B. J. Shipway

    2014-10-01

    Full Text Available Twomey's seminal 1959 paper provided lower and upper bound approximations to the estimation of peak supersaturation within an updraft and thus provides the first closed expression for the number of nucleated cloud droplets. The form of this approximation is simple, but provides a surprisingly good estimate and has subsequently been employed in more sophisticated treatments of nucleation parametrization. In the current paper, we revisit the lower bound approximation of Twomey and make a small adjustment which can be used to obtain a more accurate calculation of peak supersaturation under all potential aerosol loadings and thermodynamic conditions. In order to make full use of this improved approximation, the underlying integro-differential equation for supersaturation evolution and the condition for calculating peak supersaturation are examined. A simple rearrangement of the algebra allows for an expression to be written down which can then be solved with a single lookup table with only one independent variable for an underlying lognormal aerosol population. Multimode aerosol with only N different dispersion characteristics require only N of these one-dimensional lookup tables. No additional information is required in the lookup table to deal with additional chemical, physical or thermodynamic properties. The resulting implementation provides a relatively simple, yet computationally cheap and very accurate physically-based parametrization of droplet nucleation for use in climate and NWP models.

  2. Nursing knowledge, theory and method revisited.

    Science.gov (United States)

    Booth, K; Kenrick, M; Woods, S

    1997-10-01

    With the approach of the 21st century, nursing is having to respond to diverse influences which are remoulding the professional landscape. Not least of these is the changing status of western economies which underpins a drive towards evidence-based practice and an increased emphasis on multidisciplinary approaches to health care delivery. Certainty in health care is now a thing of the past. Central to the way the nursing profession embraces the future is its underlying philosophy: that which articulates professional values and shapes practice, research, education and management. In a time of change it is therefore essential to revisit the philosophical framework which underpins nursing. The debate in nursing research and theory appears to have stressed the polarization of viewpoints. It may be the case that feminist writers, ethnographers, positivist researchers and nursing theorists, in defending their own points of view, diminish rather than enhance professional dialogue. This paper reviews the nature of this debate within nursing and considers the implications that a dichotomous position may have for knowledge, theory and research method within the current context of health care. It then suggests a philosophical framework which could be relevant and accessible across the whole spectrum of nursing activity. In so doing, the paper aims to contribute to the discussion around epistemology and method in a way which encompasses the diversity found within the broad church of nursing. PMID:9354995

  3. Searle's"Dualism Revisited"

    Energy Technology Data Exchange (ETDEWEB)

    P., Henry

    2008-11-20

    A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

  4. Pair Production Constraints on Superluminal Neutrinos Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.

    2012-02-16

    We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p{sup 2} can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

  5. Targeting Cancer Metabolism - Revisiting the Warburg Effects

    Science.gov (United States)

    Tran, Quangdon; Lee, Hyunji; Park, Jisoo; Kim, Seon-Hwan; Park, Jongsun

    2016-01-01

    After more than half of century since the Warburg effect was described, this atypical metabolism has been standing true for almost every type of cancer, exhibiting higher glycolysis and lactate metabolism and defective mitochondrial ATP production. This phenomenon had attracted many scientists to the problem of elucidating the mechanism of, and reason for, this effect. Several models based on oncogenic studies have been proposed, such as the accumulation of mitochondrial gene mutations, the switch from oxidative phosphorylation respiration to glycolysis, the enhancement of lactate metabolism, and the alteration of glycolytic genes. Whether the Warburg phenomenon is the consequence of genetic dysregulation in cancer or the cause of cancer remains unknown. Moreover, the exact reasons and physiological values of this peculiar metabolism in cancer remain unclear. Although there are some pharmacological compounds, such as 2-deoxy-D-glucose, dichloroacetic acid, and 3-bromopyruvate, therapeutic strategies, including diet, have been developed based on targeting the Warburg effect. In this review, we will revisit the Warburg effect to determine how much scientists currently understand about this phenomenon and how we can treat the cancer based on targeting metabolism. PMID:27437085

  6. Carbon emission from global hydroelectric reservoirs revisited.

    Science.gov (United States)

    Li, Siyue; Zhang, Quanfa

    2014-12-01

    Substantial greenhouse gas (GHG) emissions from hydropower reservoirs have been of great concerns recently, yet the significant carbon emitters of drawdown area and reservoir downstream (including spillways and turbines as well as river reaches below dams) have not been included in global carbon budget. Here, we revisit GHG emission from hydropower reservoirs by considering reservoir surface area, drawdown zone and reservoir downstream. Our estimates demonstrate around 301.3 Tg carbon dioxide (CO2)/year and 18.7 Tg methane (CH4)/year from global hydroelectric reservoirs, which are much higher than recent observations. The sum of drawdown and downstream emission, which is generally overlooked, represents 42 % CO2 and 67 % CH4 of the total emissions from hydropower reservoirs. Accordingly, the global average emissions from hydropower are estimated to be 92 g CO2/kWh and 5.7 g CH4/kWh. Nonetheless, global hydroelectricity could currently reduce approximate 2,351 Tg CO2eq/year with respect to fuel fossil plant alternative. The new findings show a substantial revision of carbon emission from the global hydropower reservoirs. PMID:24943886

  7. The phylogeny of C/S1 bZIP transcription factors reveals a shared algal ancestry and the pre-angiosperm translational regulation of S1 transcripts.

    Science.gov (United States)

    Peviani, Alessia; Lastdrager, Jeroen; Hanson, Johannes; Snel, Berend

    2016-01-01

    Basic leucine zippers (bZIPs) form a large plant transcription factor family. C and S1 bZIP groups can heterodimerize, fulfilling crucial roles in seed development and stress response. S1 sequences also harbor a unique regulatory mechanism, termed Sucrose-Induced Repression of Translation (SIRT). The conservation of both C/S1 bZIP interactions and SIRT remains poorly characterized in non-model species, leaving their evolutionary origin uncertain and limiting crop research. In this work, we explored recently published plant sequencing data to establish a detailed phylogeny of C and S1 bZIPs, investigating their intertwined role in plant evolution, and the origin of SIRT. Our analyses clarified C and S1 bZIP orthology relationships in angiosperms, and identified S1 sequences in gymnosperms. We experimentally showed that the gymnosperm orthologs are regulated by SIRT, tracing back the origin of this unique regulatory mechanism to the ancestor of seed plants. Additionally, we discovered an earlier S ortholog in the charophyte algae Klebsormidium flaccidum, together with a C ortholog. This suggests that C and S groups originated by duplication from a single algal proto-C/S ancestor. Based on our observations, we propose a model wherein the C/S1 bZIP dimer network evolved in seed plants from pre-existing C/S bZIP interactions. PMID:27457880

  8. Contradiction between plastid gene transcription and function due to complex posttranscriptional splicing: an exemplary study of ycf15 function and evolution in angiosperms.

    Directory of Open Access Journals (Sweden)

    Chao Shi

    Full Text Available Plant chloroplast genes are usually co-transcribed while its posttranscriptional splicing is fairly complex and remains largely unsolved. On basis of sequencing the three complete Camellia (Theaceae chloroplast genomes for the first time, we comprehensively analyzed the evolutionary patterns of ycf15, a plastid gene quite paradoxical in terms of its function and evolution, along the inferred angiosperm phylogeny. Although many species in separate lineages including the three species reported here contained an intact ycf15 gene in their chloroplast genomes, the phylogenetic mixture of both intact and obviously disabled ycf15 genes imply that they are all non-functional. Both intracellular gene transfer (IGT and horizontal gene transfer (HGT failed to explain such distributional anomalies. While, transcriptome analyses revealed that ycf15 was transcribed as precursor polycistronic transcript which contained ycf2, ycf15 and antisense trnL-CAA. The transcriptome assembly was surprisingly found to cover near the complete Camellia chloroplast genome. Many non-coding regions including pseudogenes were mapped by multiple transcripts, indicating the generality of pseudogene transcriptions. Our results suggest that plastid DNA posttranscriptional splicing may involve complex cleavage of non-functional genes.

  9. New Distribution Record of Angiosperm in Fujian Province (IV)%福建被子植物分布新记录 IV

    Institute of Scientific and Technical Information of China (English)

    杨成梓; 刘小芬; 黄泽豪; 范世明; 吴锦忠

    2012-01-01

      According to the investigation on the vegetation in Fujian Province, 1 newly recorded genus, Arabis; and 5 newly recorded species, Arabis flagellosa, Sedum emarginatum, Sedum polytrichoides, Sedum tetractinum, Hylotelephium erythrostictum of angiosperms were reported. The voucher specimens were deposited in the Herbarium of FJTCM.%  在福建省药用植物资源调查中,陆续发现了福建省被子植物地理新分布记录属及种多个,经整理鉴定,本文继续报道1个新分布记录属(南芥属 Arabis)和5个新分布记录种(匍匐南芥 Arabis flagellosa、凹叶景天Sedum emarginatum、藓状景天 Sedum polytrichoides、四芒景天 Sedum tetractinum、八宝 Hylotelephium erythrostictum)。标本存放于福建中医药大学药用植物标本室。

  10. Plant functional types are more efficient than climate in predicting spectrums of trait variation in evergreen angiosperm trees of tropical Australia and China

    Science.gov (United States)

    Togashi, H. F.; Prentice, I. C. C.; Atkin, O. K.; Bloomfield, K. J.; Bradford, M.; Weerasinghe, L. K.; Harrison, S. P.; Evans, B. J.; Liddell, M. J.; Wang, H.; Cao, K. F.; Fan, Z.

    2015-12-01

    The representation of Plant Functional Types (PFTs) in current generation of Dynamic Global Vegetation Models (DGVMs) is excessively simplistically. Key ecophysiological properties, such as photosynthesis biochemistry, are most times merely averaged and trade-off with other plant traits is often neglected. Validation of a PFT framework based in photosynthetic process is crucial to improve reliability of DGVMs. We present 431 leaf-biochemical and wood level measurements in evergreen angiosperm trees of tropical forests in Australia and China that were divided in four spectrums of plant trait variation: metabolic, structural, hydraulic and height dimensions. Plant traits divided in each of these dimensions adopt survival strategies reflected more clearly by trade-off within each spectrum, and in some extent across spectrums. Co-ordination theory (that Rubisco- and electron-transport limited rates of photosynthesis are co-limiting) and least-coast theory (that intercellular to ambient CO2 concentration minimizes the combined costs per unit carbon assimilation, regulating maximum height and wood density) expectations matched PFT (which takes in account canopy position and light access, and life spam) variation. Our findings suggest that climate (air moisture, air temperature, light) has lower power representing these dimensions, in comparison to the PFT framework.

  11. New Distribution Record of Angiosperm in Fujian Province (Ⅲ)%福建被子植物分布新记录Ⅲ

    Institute of Scientific and Technical Information of China (English)

    杨成梓; 刘小芬; 黄泽豪; 范世明; 吴锦忠

    2012-01-01

      在福建省药用植物资源调查中,陆续发现了福建省被子植物地理新分布记录属及种多个,经整理鉴定,本文继续报道新分布记录属4个,乳豆属 Galactia、米口袋属 Gueldenstaedtia、山靛属 Mercurialis、刺芹属Eryngium,以及乳豆 Galactia tenuiflora、少花米口袋 Gueldenstaedtia verna、山靛 Mercurialis leiocarpa、刺芹Eryngium foetidum、泡果苘 Herissantia crispa 等5个新分布记录种,标本存放于福建中医药大学药用植物标本室%  According to the investigation on the vegetation in Fujian Province, 4 Newly recorded genera, Galactia, Gueldenstaedtia, Mercurialis, Eryngium, and 5 newly recorded species, Galactia tenuiflora, Gueldenstaedtia verna, Mercurialis leiocarpa, Herissantia crispa, Eryngium foetidum of Angiosperm were found. The voucher specimens were deposited in the Herbarium of FJTCM.

  12. Intramolecular Amide Hydrolysis in N-Methylmaleamic Acid Revisited

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The intramolecular amide hydrolysis of N-methylmaleamic acid have been revisited by use of density functional theory and inclusion of solvent effects. The results indicate that concerted reaction mechanism is favored over stepwise reaction mechanism. This is in agreement with the previous theoretical study. Sovlent effects have significant influence on the reaction barrier.

  13. Bohr’s ‘Light and Life’ revisited

    Science.gov (United States)

    Nussenzveig, H. M.

    2015-11-01

    I revisit Niels Bohr’s famous 1932 ‘Light and Life’ lecture, confronting it with current knowledge. Topics covered include: life origin and evolution, quantum mechanics and life, brain and mind, consciousness and free will, and light as a tool for biology, with special emphasis on optical tweezers and their contributions to biophysics. Specialized knowledge of biology is not assumed.

  14. Closing Achievement Gaps: Revisiting Benjamin S. Bloom's "Learning for Mastery"

    Science.gov (United States)

    Guskey, Thomas R.

    2007-01-01

    The problem of achievement gaps among different subgroups of students has been evident in education for many years. This manuscript revisits the work of renowned educator Benjamin S. Bloom, who saw reducing gaps in the achievement of various groups of students as a simple problem of reducing variation in student learning outcomes. Bloom observed…

  15. Educational Administration and the Management of Knowledge: 1980 Revisited

    Science.gov (United States)

    Bates, Richard

    2013-01-01

    This paper revisits the thesis of a 1980 paper that suggested a new approach to educational administration based upon the New Sociology of Education. In particular it updates answers to the six key questions asked by that paper: what counts as knowledge; how is what counts as knowledge organised; how is what counts as knowledge transmitted; how is…

  16. Transport benchmarks for one-dimensional binary Markovian mixtures revisited

    International Nuclear Information System (INIS)

    The classic benchmarks for transport through a binary Markovian mixture are revisited to look at the probability distribution function of the chosen 'results': reflection, transmission and scalar flux. We argue that the knowledge of the ensemble averaged results is not sufficient for reliable predictions: a measure of the dispersion must also be obtained. An algorithm to estimate this dispersion is tested. (author)

  17. The Wealth Paradox Revisited: Credit Market Imperfections and Child Labor

    OpenAIRE

    Congdon Fors, Heather

    2008-01-01

    We revisit the model of child labor in a peasant household presented in Bhalotra and Heady (2003), and demonstrate that the e¤ect of credit market imperfections on child labor di¤ers between households that save and households that borrow. This in turn is important for the interpretation of empirical results.

  18. Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited

    DEFF Research Database (Denmark)

    Miao, L.; Lomholt, Michael Andersen; Kleis, J.

    2002-01-01

    In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy...

  19. Additively homomorphic encryption with a double decryption mechanism, revisited

    NARCIS (Netherlands)

    Peter, A.; Kronberg, M.; Trei, W.; Katzenbeisser, S.

    2012-01-01

    We revisit the notion of additively homomorphic encryption with a double decryption mechanism (DD-PKE), which allows for additions in the encrypted domain while having a master decryption procedure that can decrypt all properly formed ciphertexts by using a special master secret. This type of encryp

  20. Revisiting Jack Goody to Rethink Determinisms in Literacy Studies

    Science.gov (United States)

    Collin, Ross

    2013-01-01

    This article revisits Goody's arguments about literacy's influence on social arrangements, culture, cognition, economics, and other domains of existence. Whereas some of his arguments tend toward technological determinism (i.e., literacy causes change in the world), other of his arguments construe literacy as a force that shapes and is shaped by…

  1. Complex and detailed balancing of chemical reaction networks revisited

    NARCIS (Netherlands)

    van der Schaft, Abraham; Rao, Shodhan; Jayawardhana, Bayu

    2015-01-01

    The characterization of the notions of complex and detailed balancing for mass action kinetics chemical reaction networks is revisited from the perspective of algebraic graph theory, in particular Kirchhoff’s Matrix Tree theorem for directed weighted graphs. This yields an elucidation of previously

  2. Revisiting the calculation of effective free distance of turbo codes

    OpenAIRE

    Chatzigeorgiou, I; Wassell, I. J.

    2008-01-01

    The expression for the minimum Hamming weight of the output of a constituent convolutional encoder, when its input is a weight-2 sequence is revisited. The new expression particularly facilitates the calculation of the effective free distance of recently proposed schemes, namely non-systematic turbo codes and pseudo-randomly punctured turbo codes.

  3. A Simple Algorithm for Maximum Margin Classification, Revisited

    OpenAIRE

    Har-Peled, Sariel

    2015-01-01

    In this note, we revisit the algorithm of Har-Peled et. al. [HRZ07] for computing a linear maximum margin classifier. Our presentation is self contained, and the algorithm itself is slightly simpler than the original algorithm. The algorithm itself is a simple Perceptron like iterative algorithm. For more details and background, the reader is referred to the original paper.

  4. A Multi-Level Model of Moral Functioning Revisited

    Science.gov (United States)

    Reed, Don Collins

    2009-01-01

    The model of moral functioning scaffolded in the 2008 "JME" Special Issue is here revisited in response to three papers criticising that volume. As guest editor of that Special Issue I have formulated the main body of this response, concerning the dynamic systems approach to moral development, the problem of moral relativism and the role of…

  5. Revisiting the Role of Organizational Effectiveness in Educational Evaluation.

    Science.gov (United States)

    Lotto, Linda S.

    Organizational effectiveness ought to play a role in educational evaluation, and the development of alternative perspectives for viewing organizations could be a starting point for revisiting organizational evaluation in education. Five possible perspectives and criteria for evaluating organizations have been developed. If an organization is…

  6. "An analysis of the classical Doppler Effect"[1] revisited

    OpenAIRE

    Rothenstein, Bernhard; Nafornita, Corina

    2004-01-01

    After having shown that the formula which describes the Doppler effect in the general case holds only in the case of the "very high" frequency assumption, we derive free of assumptions Doppler formulas for two scenarios presented in the revisited paper.

  7. The Angular Momentum of Baryons and Dark Matter Halos Revisited

    Science.gov (United States)

    Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated

  8. Revisiting El Niño Modokis

    Science.gov (United States)

    Marathe, Shamal; Ashok, Karumuri; Swapna, P.; Sabin, T. P.

    2015-12-01

    The suggestion that there exist two types of El Niño in the tropical Pacific has generated a debate in the community. Applying various linear and non-linear approaches and composite analysis technique on observed and reanalyzed climate datasets primarily for the 1950-2010 period, we revisit the variability of the tropical Pacific in the light of this debate. Our objective is to examine whether the proposed El Niño Modokis need a classification distinct from canonical El Niños. Even if the distinction is subject to short data records, we demonstrate that the El Niño Modoki events indeed display a seasonal evolution and teleconnections different from the canonical El Niños, and that the distinction is not subject to inclusion of the two extreme El Niños 1982 and 1997 as canonical El Niños. We show that the El Niño Modoki events are not an artifact associated with the orthogonality constraint associated with the EOF technique. Our cluster analysis shows that evolutions of the canonical El Niño and El Niño Modokis through various seasons differ from one another. Importantly, the dynamic and thermodynamic air-sea coupling strength is distinctly different between the El Niño Modoki and the canonical El Niño events. We find that, dynamic feedback intensity is stronger for El Niño Modoki (canonical El Niño) during boreal summer (winter); though the air-sea coupling strength, a major contributor to Bjerknes feedback, is maximum for Modokis during the developing stages, it decreases thereafter. In case of thermodynamic feedback intensity, SST-wind-evaporation feedback is dominant for El Niños while SST-SHF feedback is important during El Niño Modokis. However, we find that the thermodynamic feedback values significantly differ across the flux datasets.

  9. Clifford Algebra Implying Three Fermion Generations Revisited

    International Nuclear Information System (INIS)

    The author's idea of algebraic compositeness of fundamental particles, allowing to understand the existence in Nature of three fermion generations, is revisited. It is based on two postulates. Primo, for all fundamental particles of matter the Dirac square-root procedure √p2 → Γ(N)·p works, leading to a sequence N=1, 2, 3, ... of Dirac-type equations, where four Dirac-type matrices Γ(N)μ are embedded into a Clifford algebra via a Jacobi definition introducing four ''centre-of-mass'' and (N - 1) x four ''relative'' Dirac-type matrices. These define one ''centre-of-mass'' and N - 1 ''relative'' Dirac bispinor indices. Secundo, the ''centre-of-mass'' Dirac bispinor index is coupled to the Standard Model gauge fields, while N - 1 ''relative'' Dirac bispinor indices are all free indistinguishable physical objects obeying Fermi statistics along with the Pauli principle which requires the full antisymmetry with respect to ''relative'' Dirac indices. This allows only for three Dirac-type equations with N = 1, 3, 5 in the case of N odd, and two with N = 2, 4 in the case of N even. The first of these results implies unavoidably the existence of three and only three generations of fundamental fermions, namely leptons and quarks, as labelled by the Standard Model signature. At the end, a comment is added on the possible shape of Dirac 3 x 3 mass matrices for four sorts of spin-1/2 fundamental fermions appearing in three generations. For charged leptons a prediction is mτ = 1776.80 MeV, when the input of experimental me and mμ is used. (author)

  10. Backwardation in energy futures markets: Metalgesellschaft revisited

    International Nuclear Information System (INIS)

    Energy supply contracts negotiated by the US Subsidiary of Metalgesellschaft Refining and Marketing (MGRM), which were the subject of much subsequent debate, are re-examined. The contracts were hedged by the US Subsidiary barrel-for-barrel using short-dated energy derivatives. When the hedge program experienced difficulties, the derivatives positions were promptly liquidated by the parent company. Revisiting the MGRM contracts also provides the opportunity to explore the latest evidence on backwardation in energy markets. Accordingly, the paper discusses first the theoretical reasons for backwardation, followed by an empirical examination using the MGRM data available at the time of the hedge program in 1992 and a second set of data that became available in 2000. By using a more up-to-date data set covering a longer time period and by controlling the time series properties of the data, the authors expect to provide more reliable empirical evidence on the behaviour of energy futures prices. Results based on the 1992 data suggest that the strategy employed by MGRM could be expected to be profitable while the risks are relatively low. However, analysis based on the 2000 data shows lower, although still significant profits, but higher risks. The final conclusion was that the likelihood of problems similar to those faced by MGRM in 1992 are twice as high with the updated 2000 data, suggesting that the risk-return pattern of the stack-and-roll hedging strategy using short-dated energy future contracts to hedge long-tem contracts is less appealing now than when MGRM implemented its hedging program in 1992. 24 refs., 3 tabs., 6 figs

  11. Schwinger Effect, Hawking Radiation, and Unruh Effect

    CERN Document Server

    Kim, Sang Pyo

    2016-01-01

    We revisit the Schwinger effect in de Sitter, anti-de Sitter spaces and charged black holes, and explore the interplay between quantum electrodynamics and the quantum gravity effect at one-loop level. We then advance a thermal interpretation of the Schwinger effect in curved spacetimes. Finally, we show that the Schwinger effect in a near-extremal black hole differs from Hawking radiation of charged particles in a non-extremal black hole and is factorized into those in an anti-de Sitter space and a Rindler space with the surface gravity for acceleration.

  12. Schwinger Effect, Hawking Radiation, and Unruh Effect

    OpenAIRE

    Kim, Sang Pyo

    2016-01-01

    We revisit the Schwinger effect in de Sitter, anti-de Sitter spaces and charged black holes, and explore the interplay between quantum electrodynamics and the quantum gravity effect at one-loop level. We then advance a thermal interpretation of the Schwinger effect in curved spacetimes. Finally, we show that the Schwinger effect in a near-extremal black hole differs from Hawking radiation of charged particles in a non-extremal black hole and is factorized into those in an anti-de Sitter space...

  13. De novo assembly of the carrot mitochondrial genome using next generation sequencing of whole genomic DNA provides first evidence of DNA transfer into an angiosperm plastid genome

    Directory of Open Access Journals (Sweden)

    Iorizzo Massimo

    2012-05-01

    Full Text Available Abstract Background Sequence analysis of organelle genomes has revealed important aspects of plant cell evolution. The scope of this study was to develop an approach for de novo assembly of the carrot mitochondrial genome using next generation sequence data from total genomic DNA. Results Sequencing data from a carrot 454 whole genome library were used to develop a de novo assembly of the mitochondrial genome. Development of a new bioinformatic tool allowed visualizing contig connections and elucidation of the de novo assembly. Southern hybridization demonstrated recombination across two large repeats. Genome annotation allowed identification of 44 protein coding genes, three rRNA and 17 tRNA. Identification of the plastid genome sequence allowed organelle genome comparison. Mitochondrial intergenic sequence analysis allowed detection of a fragment of DNA specific to the carrot plastid genome. PCR amplification and sequence analysis across different Apiaceae species revealed consistent conservation of this fragment in the mitochondrial genomes and an insertion in Daucus plastid genomes, giving evidence of a mitochondrial to plastid transfer of DNA. Sequence similarity with a retrotransposon element suggests a possibility that a transposon-like event transferred this sequence into the plastid genome. Conclusions This study confirmed that whole genome sequencing is a practical approach for de novo assembly of higher plant mitochondrial genomes. In addition, a new aspect of intercompartmental genome interaction was reported providing the first evidence for DNA transfer into an angiosperm plastid genome. The approach used here could be used more broadly to sequence and assemble mitochondrial genomes of diverse species. This information will allow us to better understand intercompartmental interactions and cell evolution.

  14. The role of O2 as an electron acceptor alternative to CO2 in photosynthesis of the common marine angiosperm Zostera marina L.

    Science.gov (United States)

    Buapet, Pimchanok; Björk, Mats

    2016-07-01

    This study investigates the role of O2 as an electron acceptor alternative to CO2 in photosynthesis of the common marine angiosperm Zostera marina L. Electron transport rates (ETRs) and non-photochemical quenching (NPQ) of Z. marina were measured under saturating irradiance in synthetic seawater containing 2.2 mM DIC and no DIC with different O2 levels (air-equilibrated levels, 3 % of air equilibrium and restored air-equilibrated levels). Lowering O2 did not affect ETR when DIC was provided, while it caused a decrease in ETR and an increase in NPQ in DIC-free media, indicating that O2 acted as an alternative electron acceptor under low DIC. The ETR and NPQ as a function of irradiance were subsequently assessed in synthetic seawater containing (1) 2.2 mM DIC, air-equilibrated O2; (2) saturating CO2, no O2; and (3) no DIC, air-equilibrated O2. These treatments were combined with glycolaldehyde pre-incubation. Glycolaldehyde caused a marked decrease in ETR in DIC-free medium, indicating significant electron flow supported by photorespiration. Combining glycolaldehyde with O2 depletion completely suppressed ETR suggesting the operation of the Mehler reaction, a possibility supported by the photosynthesis-dependent superoxide production. However, no notable effect of suppressing the Mehler reaction on NPQ was observed. It is concluded that during DIC-limiting conditions, such as those frequently occurring in the habitats of Z. marina, captured light energy exceeds what is utilised for the assimilation of available carbon, and photorespiration is a major alternative electron acceptor, while the contribution of the Mehler reaction is minor. PMID:27125819

  15. Revisiting cytogenetic paradigms armed with new tools

    International Nuclear Information System (INIS)

    It could be argued that most of the fundamental tenets of radiation biology were either discovered, or subsequently confirmed, by observing eukaryotic chromosomes under the microscope. These include, but are certainly not limited to, dose-response relationships with respect to intensity (dose rate/dose fractionation) and radiation quality (LET/track structure). Chromosome aberrations are exquisitely sensitive indicators of radiation damage, and provide quantitative information of biological effect on a cell-by-cell-basis. As such, they have long been a favored endpoint for theoreticians, thereby figuring prominently in the development of generalized models of radiation action. Most of these seminal contributions to radiation biology occurred over a period of time when cytogenetic techniques were, of course, less refined than today. Considering the increasing rate at which technological advances have been made available to the researcher over the past few years, a reexamination of some of the radiological principles that cytogenetics helped to found seems in order. As an example of such effort, this talk will center around improvements to the use of whole chromosome painting by FISH- principally combinatorial painting techniques like mFISH and SKY- for the purposes of examining in greater detail structural aberrations to chromosomes produced following exposure to ionizing radiations of differing quality and intensity. This and related approaches by various laboratories around the world have turned up a few surprise discoveries that do not always fit established paradigms, and which serve to sharpen arguments that have been used to buttress existing models of aberration formation

  16. Revisit ocean thermal energy conversion system

    International Nuclear Information System (INIS)

    by-products, especially drinking water, aquaculture and mariculture, can easily translate into billions of dollars in business opportunities. The current status of the OTEC system definitely deserves to be carefully revisited. This paper will examine recent major advancements in technology, evaluate costs and effectiveness, and assess the overall market environment of the OTEC system and describe its great renewable energy potential and overall benefits to the nations of the world

  17. Nuclear non-proliferation: Revisiting the basics

    International Nuclear Information System (INIS)

    The 1970 Treaty on the Non- Proliferation of Nuclear Weapons (NPT), with 188 States party, represents the cornerstone of the global nuclear non-proliferation and disarmament effort -- and despite recent challenges, it has never been more relevant than it is today. But if we are to move forward, it is essential to revisit a number of the basic assumptions and features of the existing regime, and consider a number of new approaches. A key assumption at the core of the NPT was that the asymmetry between nuclear-weapon States and non-nuclear-weapon States would gradually disappear. Progress has been made on the nuclear disarmament front, but much more remains to be done. Nuclear disarmament strategies have for the most part focused on the negotiation of bilateral nuclear arms control agreements between the holders of the two largest nuclear arsenals, and a few multilateral agreements designed to curb the quantitative and qualitative development of nuclear weapons. With the end of the Cold War as an impetus, some progress was made in the early and mid-1990s, but the process unfortunately slowed in the latter part of the decade. The discoveries of a clandestine nuclear weapon programme in Iraq after the 1991 Gulf War made it painfully clear that the IAEA verification system, with its focus on declared nuclear activities and its limited rights of access to information and sites, was not adequate for the IAEA to provide the comprehensive peaceful use assurances required under the NPT. This stark realization prompted the international community to significantly expand the IAEA's verification rights. These new rights were incorporated into a 1997 protocol additional to safeguards agreements, with a request for all States to subscribe to it. For the IAEA to provide the required assurances, it must have the required authority. It is clear that the success of the IAEA verification regime will depend heavily on achieving universal adherence to the required safeguards agreements

  18. Spectral brilliance of channeling radiation at the ASTA photoinjector

    International Nuclear Information System (INIS)

    We study channeling radiation from electron beams with energies under 100 MeV. We introduce a phenomenological model of dechanneling, correct nonradiative transition rates from thermal scattering, and discuss in detail the population dynamics in low-order bound states. These are used to revisit the X-ray properties measured at the ELBE facility in Forschungszentrum Dresden Rosenstock (FZDR), extract parameters for dechanneling states, and obtain satisfactory agreement with measured photon yields. The importance of rechanneling phenomena in thick crystals is emphasized. The model is then used to calculate the expected X-ray energies, linewidths and brilliance for forthcoming channeling radiation experiments at Fermilab's ASTA photoinjector

  19. The significance test controversy revisited the fiducial Bayesian alternative

    CERN Document Server

    Lecoutre, Bruno

    2014-01-01

    The purpose of this book is not only to revisit the “significance test controversy,”but also to provide a conceptually sounder alternative. As such, it presents a Bayesian framework for a new approach to analyzing and interpreting experimental data. It also prepares students and researchers for reporting on experimental results. Normative aspects: The main views of statistical tests are revisited and the philosophies of Fisher, Neyman-Pearson and Jeffrey are discussed in detail. Descriptive aspects: The misuses of Null Hypothesis Significance Tests are reconsidered in light of Jeffreys’ Bayesian conceptions concerning the role of statistical inference in experimental investigations. Prescriptive aspects: The current effect size and confidence interval reporting practices are presented and seriously questioned. Methodological aspects are carefully discussed and fiducial Bayesian methods are proposed as a more suitable alternative for reporting on experimental results. In closing, basic routine procedures...

  20. Revisiting the Panko-Halverson Taxonomy of Spreadsheet Errors

    OpenAIRE

    Panko, Raymond R.

    2008-01-01

    The purpose of this paper is to revisit the Panko-Halverson taxonomy of spreadsheet errors and suggest revisions. There are several reasons for doing so: First, the taxonomy has been widely used. Therefore, it should have scrutiny; Second, the taxonomy has not been widely available in its original form and most users refer to secondary sources. Consequently, they often equate the taxonomy with the simplified extracts used in particular experiments or field studies; Third, perhaps as a consequ...

  1. The Houk–List transition states for organocatalytic mechanisms revisited

    OpenAIRE

    Armstrong, Alan; Boto, Roberto A.; Dingwall, Paul; Contreras-Garcia, Julia; Harvey, Matt J; Mason, Nicholas J; Rzepa, Henry S

    2014-01-01

    The ten year old Houk–List model for rationalising the origin of stereoselectivity in the organocatalysed intermolecular aldol addition is revisited, using a variety of computational techniques that have been introduced or improved since the original study. Even for such a relatively small system, the role of dispersion interactions is shown to be crucial, along with the use of basis sets where the superposition errors are low. An NCI (non-covalent interactions) analysis of the transition sta...

  2. China in 2005 Revisited: The Implications of International Capital Mobility

    OpenAIRE

    Ianchovichina, Elena; McDougall, Robert; Hertel, Thomas

    2000-01-01

    This paper revisits the analysis of the implications of China's economic growth on her trading partners presented in Arndt et al. (1997) using a dynamic, applied general equilibrium model that features international capital mobility. We find that accounting for the impact of China's growth on international capital markets reverses some of the findings in the paper by Arndt et al. In particular, net creditor regions lose while net debtor regions benefit from an economic slowdown in China du...

  3. Indoor air and human health revisited: A recent IAQ symposium

    Energy Technology Data Exchange (ETDEWEB)

    Gammage, R.B.

    1994-12-31

    Indoor Air and Human Health Revisited was a speciality symposium examining the scientific underpinnings of sensory and sensitivity effects, allergy and respiratory disease, neurotoxicity and cancer. An organizing committee selected four persons to chain the sessions and invite experts to give state-of-the-art presentations that will be published as a book. A summary of the presentations is made and some critical issues identified.

  4. Cost-sensitive learning and decision making revisited.

    OpenAIRE

    Viaene, Stijn; Dedene, Guido

    2005-01-01

    In many real-life decision making situations the default assumption of equal misclassification costs underlying pattern recognition techniques is most likely violated. Then, cost-sensitive learning and decision making bring help for making cost-benefit-wise optimal decisions. This paper brings an up-to-date overview of several methods that aim to make a broad variety of error-based learners cost-sensitive. More specifically, we revisit direct minimum expected cost classification, MetaCost, ov...

  5. Revisiting Barriers to Trade: Do Foregone Health Benefits Matter?

    OpenAIRE

    Zhang, Sidi; Kerr, William A.

    2009-01-01

    This paper examins the question of revisiting the imposition of existing trade barriers in one case of an evolving marketplace – when a traditional food product is altered to provide, or discovered to have, human health benefits that increases their value to consumers. In other words, the food becomes a functional food. A functional food has the potential provide direct benefits to consumers as well as indirect benefits to society in the form of health care cost savings. If the trade barrier ...

  6. Probit Model Estimation Revisited: Trinomial Models of Household Car Ownership

    OpenAIRE

    Bunch, David S; Kitamura, Ryuichi

    1991-01-01

    In this paper we revisit various important issues relating to practical estimation of the multinomial probit model, using an empirical analysis of car ownership as a test case. To provide context, a brief literature review of empirical probit studies is included. Estimates are obtained for a full range of model specifications, including models with random (uncorrelated and correlated) taste variation and/or a general random error structure, and issues of estimability, specification testing, a...

  7. The transverse momentum dependent statistical parton distributions revisited

    OpenAIRE

    Bourrely, Claude; Buccella, Franco; Soffer, Jacques

    2013-01-01

    The extension of the statistical parton distributions to include their transverse momentum dependence (TMD) is revisited by considering that the proton target has a finite longitudinal momentum. The TMD will be generated by means of a transverse energy sum rule. The new results are mainly relevant for electron-proton inelastic collisions in the low $Q^2$ region. We take into account the effects of the Melosh-Wigner rotation for the helicity distributions.

  8. The Transverse Momentum Dependent Statistical Parton Distributions Revisited

    Science.gov (United States)

    Bourrely, Claude; Buccella, Franco; Soffer, Jacques

    2013-04-01

    The extension of the statistical parton distributions to include their transverse momentum dependence (TMD) is revisited by considering that the proton target has a finite longitudinal momentum. The TMD will be generated by means of a transverse energy sum rule. The new results are mainly relevant for electron-proton inelastic collisions in the low Q2 region. We take into account the effects of the Melosh-Wigner rotation for the helicity distributions.

  9. Simulation of Two-Way Pushdown Automata Revisited

    OpenAIRE

    Robert Glück

    2013-01-01

    The linear-time simulation of 2-way deterministic pushdown automata (2DPDA) by the Cook and Jones constructions is revisited. Following the semantics-based approach by Jones, an interpreter is given which, when extended with random-access memory, performs a linear-time simulation of 2DPDA. The recursive interpreter works without the dump list of the original constructions, which makes Cook's insight into linear-time simulation of exponential-time automata more intuitive and the complexity arg...

  10. The angular momentum of baryons and dark matter halos revisited

    OpenAIRE

    Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive mesh refinement, we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole....

  11. Trade and civil conflict : revisiting the cross-country evidence

    OpenAIRE

    Cali, Massimiliano; Mulabdic, Alen

    2014-01-01

    This paper revisits and expands the evidence on the impact of trade shocks on intra-state conflict with a large sample of developing countries in the 1960-2010 period. The results suggest that increases in the prices of a country's exported commodities raise the country's risk of civil conflict and its duration. The effect on conflict risk is mainly driven by the price of point-source comm...

  12. Revisiting regional trade agreements and their impact on services trade

    OpenAIRE

    Marconini, Mario

    2009-01-01

    This issue paper, titled 'Revisiting Regional Trade Agreements and Their Impact on Services Trade' written by Mr. Mario Marconini, is a contribution to that process. The paper exhaustively reviews services disciplines included in several Free Trade Agreements (FTA). The aim of the paper is to enable stakeholders to understand how rules and commitments regarding trade in services have been introduced in FTAs, and how those policies might impact sustainable development in developing countries. ...

  13. New Families in the Stable Homotopy of Spheres Revisited

    Institute of Scientific and Technical Information of China (English)

    LIN Jin Kun

    2002-01-01

    This paper constructs a new family in the stable homotopy of spheres πt-6S representedby hngoγ3 ∈ E26,t in the Adams spectral sequence which revisits the bn-1g0γ3-elements ∈πt-7S con-structed in [3], where t = 2pn(p- 1) +6(p2 + p+ 1)(p- 1) and p ≥ 7 is a prime, n ≥ 4.

  14. Revisiting k-means: New Algorithms via Bayesian Nonparametrics

    OpenAIRE

    Kulis, Brian; Jordan, Michael I.

    2011-01-01

    Bayesian models offer great flexibility for clustering applications---Bayesian nonparametrics can be used for modeling infinite mixtures, and hierarchical Bayesian models can be utilized for sharing clusters across multiple data sets. For the most part, such flexibility is lacking in classical clustering methods such as k-means. In this paper, we revisit the k-means clustering algorithm from a Bayesian nonparametric viewpoint. Inspired by the asymptotic connection between k-means and mixtures...

  15. Revisiting the Response Mechanism of Polymeric Membrane Based Heparin Electrodes

    OpenAIRE

    Bell, Andrea K.; Höfler, Lajos; Meyerhoff, Mark E.

    2011-01-01

    Potentiometric membrane electrodes that respond to heparin and other polyanions were introduced in the early 1990s. Herein, the mechanism of polymer membrane electrode type heparin sensors is revisited. The extraction/diffusion of heparin is studied via both potentiometric and impedance spectroscopic techniques using a pre-fractionated heparin preparation that contains polyanionic species > 10000 Daltons. The reversal in EMF response using this heparin preparation indicates diffusion of highe...

  16. The Dutch Disease revisited: absorption constraint and learning by doing

    OpenAIRE

    Iacono, Roberto

    2014-01-01

    This paper revisits the Dutch disease by analyzing the general equilibrium effects of a resource shock on a dependent economy, both in a static and dynamic setting. The novel aspect of this study is to incorporate two features of the Dutch disease literature that have only been analyzed in isolation from each other: capital accumulation with absorption constraint and productivity growth induced by learning by doing. The conventional result of long-run exchange rate appreciation is maintained ...

  17. Audit probability versus effectiveness: The Beckerian approach revisited

    OpenAIRE

    Rablen, M

    2014-01-01

    This is the accepted version of the following article: RABLEN, M. D. (2014), Audit Probability versus Effectiveness: The Beckerian Approach Revisited. Journal of Public Economic Theory, 16: 322–342, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/jpet.12062/abstract. The Beckerian approach to tax compliance examines how a tax authority can maximize social welfare by trading-off audit probability against the fine rate on undeclared tax. This paper offers...

  18. Clausius/Cosserat/Maxwell/Weyl Equations: The Virial Theorem Revisited

    OpenAIRE

    Pommaret, Jean-François

    2015-01-01

    This paper must be published under the title " FROM THERMODYNAMICS TO GAUGE THEORY: THE VIRIAL THEOREM REVISITED " as a chapter of a forthcoming book " GAUGE THEORY AND DIFFERENTIAL GEOMETRY " published by Nova Editors. In 1870, R. Clausius found the virial theorem which amounts to introduce the trace of the stress tensor when studying the foundations of thermodynamics, as a way to relate the absolute temperature of an ideal gas to the mean kinetic energy of its molecules. In 1901, H. Poin...

  19. Radiation dosimetry.

    OpenAIRE

    Cameron, J.

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists.

  20. Aplanatic lenses revisited: the full landscape.

    Science.gov (United States)

    Mashaal, Heylal; Feuermann, Daniel; Gordon, Jeffrey M

    2016-04-01

    The full scope of solutions for dual-contour aplanatic lenses that can approach the basic limit for radiation transfer are identified, analyzed, and illustrated. Complementary solutions are shown to yield lenses that are either monolithic or have two refractive contours separated by an air gap. The performance of a promising representative design for LED collimation is presented. PMID:27139654

  1. Sequencing of the needle transcriptome from Norway spruce (Picea abies Karst L. reveals lower substitution rates, but similar selective constraints in gymnosperms and angiosperms

    Directory of Open Access Journals (Sweden)

    Chen Jun

    2012-11-01

    09and 1.1 × 10−09 is an order of magnitude smaller than values reported for angiosperm herbs. However, if one takes generation time into account, most of this difference disappears. The estimates of the dN/dS ratio (non-synonymous over synonymous divergence reported here are in general much lower than 1 and only a few genes showed a ratio larger than 1.

  2. Radiation stimulated light phenomena; Strahlungsinduzierte Leuchtphaenomene. Ein historisch-didaktischer Beitrag zur Erforschung von stimulierten Lumineszenz- und Radiolumineszenzerscheinungen mit low-light-Kameras

    Energy Technology Data Exchange (ETDEWEB)

    Schwankner, Robert Josef [Hochschule Muenchen (Germany). Radiometrisches Seminar

    2011-07-01

    Broad availability of low-light cameras invites to revisit a series of physicochemical phenomena, both in a qualitative and quantitative way. The range spans from mechanical, X-, electrical discharge stimulated luminescence to particle induced radioluminescence. Radium-doped luminophores are available for investigation of radiation damaging, as well as homogeneity analysis of faint VIS decay signatures in time and space. (orig.)

  3. Vertebrate radiations of the Jehol Biota and their environmental background

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhonghe

    2004-01-01

    @@ Significant progress has been made in recent years in the studies of various groups of the Jehol Biota, particularly concerning the origin of birds and their flight as well as the evolution of Early Cretaceous birds, dinosaurs, mammals, insects and flowering plants[1-5]. As a result, the Jehol Biota has become well known to both the scientific community and the public. The studies on the Jehol Biota also revealed the patterns and processes of the evolutionary radiations of many major groups of Early Cretaceous animals and plants, such as the earliest known radiation of angiosperms and birds, early differentiation of mammals and many Cretaceous dinosaurian groups. Notably, the radiations of the Jehol vertebrates share some similar patterns attributable to the particular environmental background. For instance, the Jehol vertebrate radiations are highlighted by the presence of abundant arboreal adaptations and herbivorous forms, thus closely linked to the forest environments. In addition, the differentiation of habitats and diets is also characteristic of the evolutionary radiations of pterosaurs, dinosaurs, birds and mammals in the Jehol Biota.

  4. REVISITING THE FIRST GALAXIES: THE EFFECTS OF POPULATION III STARS ON THEIR HOST GALAXIES

    International Nuclear Information System (INIS)

    We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the adaptive refinement tree code. Our simulations feature a recently developed model for H2 formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III (Pop III) stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch during which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies that host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 108 years after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with a total mass in excess of 3 × 106 M☉ re-accrete most of their baryons and transition to metal-enriched Pop II star formation

  5. Lunar eclipse theory revisited: Scattered sunlight in both the quiescent and the volcanically perturbed atmosphere

    International Nuclear Information System (INIS)

    The residual brightness of the shadowed Moon during a lunar eclipse is attributed to unscattered sunlight rays refracted in the Earth's atmosphere. The classical theory of lunar eclipses is built on the premise that the sunlight scattered by the gases and particles in the atmosphere contributes negligibly to the brightness of the eclipsed Moon. The current work revisits the lunar eclipse theory, extending it to accommodate spectrally resolved observations and addressing the role of scattered sunlight. Predictions of both direct and diffuse sunlight are produced by integrating the radiative transfer equations over the Earth's disk. The investigation contemplates scenarios of normal aerosol loading as well as conditions representative of the months and years following a major volcanic eruption. It is shown that omitting scattered sunlight is an acceptable approximation for low and moderate aerosol loadings at visible and longer wavelengths. However, towards the ultraviolet, or at times when the atmosphere contains elevated aerosol amounts, the relative significance of direct and diffuse sunlight may reverse. Spectra of the sunlight that reaches the shadowed Moon during the eclipse are presented to illustrate the distinct contributions from both components. It is also shown that lunar eclipse spectra obtained up to 4-5 years after a major volcanic eruption, such as Mt. Pinatubo's in 1991, will reveal that the stratosphere remains perturbed above background aerosol levels.

  6. Revisiting The First Galaxies: The effects of Population III stars on their host galaxies

    CERN Document Server

    Muratov, Alexander L; Gnedin, Nickolay Y; Zemp, Marcel

    2012-01-01

    We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the ART code. Our simulations feature a recently developed model for H2 formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a new recipe for the formation of metal-free Population III stars. We find the epoch during which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies which host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 10^8 yr after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they will typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies more massive than ...

  7. Ninety-nine years of radiation injuries in dental radiography

    International Nuclear Information System (INIS)

    A German dentist, F.O. Walkhoff, has started dental radiography as early as two weeks after Roentgen's discovery on November 8, 1895. The purpose of this paper is to revisit radiation injuries by dividing the era into the era of Kells (before World War II) and the era of low exposure doses (after World War II). Edmund Kells (1856-1928), a pioneer of dental radiologist in the United States, has later become a victim of radiation injuries. During the era of Kells, skin radiation injuries were frequent among the group of dental and medical personnels. In the era of low exposure doses, cancers, leukemia, and genetic effects have begun to receive attention. Radiation injuries occurring in a dental practice are discussed in the context of the two eras. (N.K.) 43 refs

  8. Ninety-nine years of radiation injuries in dental radiography

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Kadzuo (Nippon Dental Univ., Niigata (Japan). School of Dentistry at Niigata)

    1994-06-01

    A German dentist, F.O. Walkhoff, has started dental radiography as early as two weeks after Roentgen's discovery on November 8, 1895. The purpose of this paper is to revisit radiation injuries by dividing the era into the era of Kells (before World War II) and the era of low exposure doses (after World War II). Edmund Kells (1856-1928), a pioneer of dental radiologist in the United States, has later become a victim of radiation injuries. During the era of Kells, skin radiation injuries were frequent among the group of dental and medical personnels. In the era of low exposure doses, cancers, leukemia, and genetic effects have begun to receive attention. Radiation injuries occurring in a dental practice are discussed in the context of the two eras. (N.K.) 43 refs.

  9. A practical method of predicting client revisit intention in a hospital setting.

    Science.gov (United States)

    Lee, Kyun Jick

    2005-01-01

    Data mining (DM) models are an alternative to traditional statistical methods for examining whether higher customer satisfaction leads to higher revisit intention. This study used a total of 906 outpatients' satisfaction data collected from a nationwide survey interviews conducted by professional interviewers on a face-to-face basis in South Korea, 1998. Analyses showed that the relationship between overall satisfaction with hospital services and outpatients' revisit intention, along with word-of-mouth recommendation as intermediate variables, developed into a nonlinear relationship. The five strongest predictors of revisit intention were overall satisfaction, intention to recommend to others, awareness of hospital promotion, satisfaction with physician's kindness, and satisfaction with treatment level. PMID:15923917

  10. Radiation protection

    International Nuclear Information System (INIS)

    This work define procedures and controls about ionizing radiations. Between some definitions it found the following topics: radiation dose, risk, biological effects, international radioprotection bodies, workers exposure, accidental exposure, emergencies and radiation protection

  11. Isotropic Radiators

    CERN Document Server

    Matzner, H; Matzner, Haim; Donald, Kirk T. Mc

    2003-01-01

    We give two examples of antennas with isotropic radiation patterns. Because these involve elliptically polarized radiation, they evade the "hairy-ball theorem" that suggests isotropic radiation would be impossible.

  12. Revisiting radiotherapy in head and neck cancers

    International Nuclear Information System (INIS)

    Head and neck cancers form 20% of the total cancers in India. It comprise of soft tissue neoplasms of oral/nasal cavity and paranasal sinuses/pharynx/larynx and salivary glands. Majority of them are squamous cell carcinomas, which shows a higher prevalence among rural population in the 4th decade of life with an equal male-female ratio. Buccal mucosa is the commonest site followed by tongue. Tobacco/related products and alcohol are its major causative factors. Though surgical resection is the main treatment modality; patients in the advanced stages of disease or those with multiple/extensive lymph node involvement are done through a multi-disciplinary approach involving radiation therapy. Typical doses of 60Cobalt irradiation are from 30-72 Grays (Gy). Overall treatment is from 15 to 80 days with a dose per fraction ranging from 1.8-6 Gy. High doses cause mouth sores/dry mouth/dysphagia/dysgeusia/jaw stiffness. However, modern radiation protocols considerably minimize exposure to healthy tissues. This paper evaluates the radiotherapy systems for head and neck cancers in the contemporary and future domains. (author)

  13. Large scale geometry and evolution of a universe with radiation pressure and cosmological constant

    CERN Document Server

    Coquereaux, Robert; Coquereaux, Robert; Grossmann, Alex

    2000-01-01

    In view of new experimental results that strongly suggest a non-zero cosmological constant, it becomes interesting to revisit the Friedmann-Lemaitre model of evolution of a universe with cosmological constant and radiation pressure. In this paper, we discuss the explicit solutions for that model, and perform numerical explorations for reasonable values of cosmological parameters. We also analyse the behaviour of redshifts in such models and the description of ``very large scale geometrical features'' when analysed by distant observers.

  14. Radiation dosimetry

    CERN Document Server

    Hine, Gerald J; Hine, Gerald J

    1956-01-01

    Radiation Dosimetry focuses on the advancements, processes, technologies, techniques, and principles involved in radiation dosimetry, including counters and calibration and standardization techniques. The selection first offers information on radiation units and the theory of ionization dosimetry and interaction of radiation with matter. Topics include quantities derivable from roentgens, determination of dose in roentgens, ionization dosimetry of high-energy photons and corpuscular radiations, and heavy charged particles. The text then examines the biological and medical effects of radiation,

  15. Fourth-order gravity as the inflationary model revisited

    CERN Document Server

    Kaneda, S; Watanabe, N

    2010-01-01

    We revisit the simplest (fourth-order or quadratically generated) modified gravity model in four space-time dimensions. It is equivalent to the certain quintessence model via a Legendre-Weyl transform. By using the quintessence scalar potential we compute the (CMB) observables of inflation associated with curvature perturbations (namely, the scalar and tensor spectral indices, and the tensor-to-scalar ratio) by using the most recent WMAP5 experimental bound. Our results include the next-to-leading terms with respect to the inverse number of e-foldings.

  16. Revisiting perfect fluid dark matter: Observational constraints from our galaxy

    OpenAIRE

    Potapov, Alexander A.; Garipova, Guzel M.; Nandi, Kamal K.

    2016-01-01

    We revisit certain features of an assumed spherically symmetric perfect fluid dark matter halo in the light of the observed data of our galaxy, the Milky Way (MW). The idea is to apply the Faber–Visser approach of combined observations of rotation curves and lensing to a first post-Newtonian approximation to “measure” the equation of state ω(r) of the perfect fluid galactic halo. However, for the model considered here, no constraints from lensing are used as it will be sufficient to consider ...

  17. Nonextensive Nambu Jona-Lasinio model of QCD matter revisited

    CERN Document Server

    Rozynek, Jacek

    2016-01-01

    We present a revisited version of the nonextensive QCD-based Nambu - Jona-Lasinio (NJL) model describing the behavior of strongly interacting matter proposed by us some time ago. As before, it is based on the nonextensive generalization of the Boltzmann-Gibbs (BG) statistical mechanics used in the NJL model to its nonextensive version based on Tsallis statistics, but this time it fulfils the basic requirements of thermodynamical consistency. Different ways in which this can be done, connected with different possible choices of the form of the corresponding nonextensive entropies, are presented and discussed in detail. The corresponding results are compared, discussed and confronted with previous findings.

  18. Revisiting reflexology: Concept, evidence, current practice, and practitioner training

    OpenAIRE

    Embong, Nurul Haswani; Soh, Yee Chang; Ming, Long Chiau; Wong, Tin Wui

    2015-01-01

    Reflexology is basically a study of how one part of the human body relates to another part of the body. Reflexology practitioners rely on the reflexes map of the feet and hands to all the internal organs and other human body parts. They believe that by applying the appropriate pressure and massage certain spots on the feet and hands, all other body parts could be energized and rejuvenated. This review aimed to revisit the concept of reflexology and examine its effectiveness, practices, and th...

  19. Modulational instability in a passive fiber cavity, revisited.

    Science.gov (United States)

    Zezyulin, D A; Konotop, V V; Taki, M

    2011-12-01

    Modulation instability in a passive fiber cavity is revisited. We address the problem in the statement with a continuous-time Ikeda map, rather than in the mean-field limit. It is found that plane wave solutions are unstable for both normal and anomalous dispersion regimes of an optical fiber. The origin of the instability in the continuous-time Ikeda map is in the mode mixing introduced by the beam splitter. The obtained conditions for the instability were compared with ones known for the discrete-time Ikeda map, showing appreciable difference, which, however reduces in the mean-field limit. PMID:22139263

  20. Hyperbranched polymer stars with Gaussian chain statistics revisited.

    Science.gov (United States)

    Polińska, P; Gillig, C; Wittmer, J P; Baschnagel, J

    2014-02-01

    Conformational properties of regular dendrimers and more general hyperbranched polymer stars with Gaussian statistics for the spacer chains between branching points are revisited numerically. We investigate the scaling for asymptotically long chains especially for fractal dimensions df = 3 (marginally compact) and df = 2.5 (diffusion limited aggregation). Power-law stars obtained by imposing the number of additional arms per generation are compared to truly self-similar stars. We discuss effects of weak excluded-volume interactions and sketch the regime where the Gaussian approximation should hold in dense solutions and melts for sufficiently large spacer chains. PMID:24574057

  1. Small-angle scattering theory revisited: Photocurrent and spatial localization

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Michelsen, Poul

    2005-01-01

    In this paper theory on collective scattering measurements of electron density fluctuations in fusion plasmas is revisited. We present the first full derivation of the expression for the photocurrent beginning at the basic scattering concepts. Thereafter we derive detailed expressions for the auto......- and crosspower spectra obtained from measurements. These are discussed and simple simulations made to elucidate the physical meaning of the findings. In this context, the known methods of obtaining spatial localization are discussed and appraised. Where actual numbers are applied, we utilize....... Saffman et al., "CO2 laser based two-volume collective scattering instrument for spatially localized turbulence measurements,"Rev. Sci. Instrum. 72, 2579-2592 (2001)]....

  2. Radiation Hydrodynamics

    Science.gov (United States)

    Mihalas, Dimitri

    Basic Radiation Theory Specific Intensity Photon Number Density Photon Distribution Function Mean Intensity Radiation Energy Density Radiation Energy Flux Radiation Momentum Density Radiation Stress Tensor (Radiation Pressure Tensor) Thermal Radiation Thermodynamics of Thermal Radiation and a Perfect Gas The Transfer Equation Absorption, Emission, and Scattering The Equation of Transfer Moments of the Transfer Equation Lorentz Transformation of the Transfer Equation Lorentz Transformation of the Photon 4-Momentum Lorentz Transformation of the Specific Intensity, Opacity, and - Emissivity Lorentz Transformation of the Radiation Stress Energy Tensor The Radiation 4-Force Density Vector Covariant Form of the Transfer Equation Inertial-Frame Equations of Radiation Hydrodynamics Inertial-Frame Radiation Equations Inertial-Frame Equations of Radiation Hydrodynamics Comoving-Frame Equation of Transfer Special Relativistic Derivation (D. Mihalas) Consistency Between Comoving-Frame and Inertial-Frame Equations Noninertial Frame Derivation (J. I. Castor) Analysis of O (v/c) Terms Lagrangian Equations of Radiation Hydrodynamics Momentum Equation Gas Energy Equation First Law of Thermodynamics for the Radiation Field First Law of Thermodynamics for the Radiating Fluid Mechanical Energy Equation Total Energy Equation Consistency of Different Forms of the Radiating-Fluid Energy - and Momentum Equations Consistency of Inertial-Frame and Comoving-Frame Radiation Energy - and Momentum Equations Radiation Diffusion Radiation Diffusion Nonequilibrium Diffusion The Problem of Flux Limiting Shock Propagation: Numerical Methods Acoustic Waves Numerical Stability Systems of Equations Implications of Shock Development Implications of Diffusive Energy Transport Illustrative Example Numerical Radiation Hydrodynamics Radiating Fluid Energy and Momentum Equations Computational Strategy Energy Conservation Formal Solution Multigroup Equations An Astrophysical Example Adaptive-Grid Radiation

  3. Cytological study of radiation induced alterations in cytoplasmic factors controlling male sterility in corn. Progress report, February 28, 1975--December 1, 1975

    International Nuclear Information System (INIS)

    Progress is reported on the following research projects: cytoplasmic constituents of the embryo of various gymnosperms and angiosperms; cytoplasmic male sterility in corn; modification of cytoplasmic sterility factors using gamma radiation, EMS, and ethidium bromide; selection for sterile, blight-resistant corn plants; electron microscopy study of abnormal mitochondria in cytoplasm of corn; cytoplasmic male sterility in Petunia; non-Mendelian variegation in Petunia and Nicotiana; graft transmission of cytoplasmic male sterility; cytoplasmic male sterility in Vicia faba; and studies on Blakeslee's I virus in Datura

  4. Particle Filtering for Attitude Estimation Using a Minimal Local-Error Representation: A Revisit

    OpenAIRE

    Chang, Lubin

    2014-01-01

    In this note, we have revisited the previously published paper "Particle Filtering for Attitude Estimation Using a Minimal Local-Error Representation". In the revisit, we point out that the quaternion particle filtering based on the local/global representation structure has not made full use of the advantage of the particle filtering in terms of accuracy and robustness. Moreover, a normalized quaternion determining procedure based on the minimum mean-square error approach has been investigate...

  5. Engineered nanoparticles: Revisiting safety concerns in light of ethno medicine

    Science.gov (United States)

    Palkhiwala, Suhani; Bakshi, Sonal R.

    2014-01-01

    The nanoparticles are a miracle invention of the century that has opened novel avenues of applications in various fields. The safety aspect of exposure to nanoparticles for humans, plants, animals, soil micro-flora, and ecosystem at large has been questioned. The safety concern can be addressed by laboratory studies to assess the actual risk and recommend exposure limits and related regulation. There is also a suggestion for considering the nanoparticle form of conventional compounds as a new chemical and subject it to safety assessment in line with the chemical regulatory agencies. In the light of the current scenario of popularity and safety concerns regarding nanoparticles, the use of ancient metal based forms like, Bhasma is revisited in the present article. The current approach of green synthesis of nanoparticles is compared with the Ayurveda Rasayana Shastra guidelines of Bhasma preparation and modern preparation of engineered nanoparticles. Since the benefits of nanotechnology are undeniable, and safety concerns are also not ungrounded, there is a pressing need to revisit the ways nanoparticles are manufactured, and to carry out safety assessment by the techniques specially adapted for this novel compound. PMID:26664232

  6. Review - Revisiting Rituals in a Changing Tibetan World

    Directory of Open Access Journals (Sweden)

    Christina Kilby

    2013-12-01

    Full Text Available Review of: Katia Buffetrille (ed. 2012. Revisiting Rituals in a Changing Tibetan World. Leiden: Brill. Volume 31 in Brill's Tibetan Studies Library. Featuring Buddhist ritual life in its diverse manifestations across the Tibetan Plateau, this volume engages the task of defining 'ritual' by analyzing moments of ritual change. Whether political regime change, technological innovation, or social upheaval, external catalysts of religious transformation have been prominently visible in the Tibetan cultural world since the mid-twentieth century. This volume takes up the sociopolitical shifts of the recent period as a call to investigate how rituals change under fire, thereby furthering our understanding of the relationship between ritual structures and the historical contexts in which they find expression. Ritual's intertwinement with political events, symbols, and attitudes is the resounding theme presented herein, as each chapter makes efforts to disambiguate the complex causes and contours of ritual change in a particular case study. Several chapters seek to distinguish deep structural transformation in ritual from the harnessing of ritual elements for single instances of political or social action. Others debate the ambiguous role of spaces, practices, or ideas that are employed in ritual but also in political or economic contexts. Finally, each chapter challenges in some way the polarization of ritual conservatism and the 'invention of tradition' (Ranger and Hobsbawm 1983. Revisiting Rituals is an edited collection of conference papers...

  7. Radiation carcinogenesis

    International Nuclear Information System (INIS)

    This general discussion is dealt with under the following headings: problems of collecting information (epidemiology, experimental animal studies), the temporal stages of radiation action (physical and chemical effects and cellular response), human cancer, radiation dose and risk, epidemiology and dose-response relationships, cellular and molecular processes (cell inactivation, chromosome damage and cell mutation, radiation transformation, virus and oncogene activation, free radical aspects of radiation carcinogenesis, interaction of radiation and chemical carcinogens. (U.K.)

  8. Relic neutrino decoupling with flavour oscillations revisited

    CERN Document Server

    de Salas, Pablo F

    2016-01-01

    We study the decoupling process of neutrinos in the early universe in the presence of three-flavour oscillations. The evolution of the neutrino spectra is found by solving the corresponding momentum-dependent kinetic equations for the neutrino density matrix, including for the first time the proper collision integrals for both diagonal and off-diagonal elements. This improved calculation modifies the evolution of the off-diagonal elements of the neutrino density matrix and changes the deviation from equilibrium of the frozen neutrino spectra. However, it does not vary the contribution of neutrinos to the cosmological energy density in the form of radiation, usually expressed in terms of the effective number of neutrinos, N_eff. We find a value of N_eff=3.045, in agreement with previous theoretical calculations and consistent with the latest analysis of Planck data. This result does not depend on the ordering of neutrino masses. We also consider the effect of non-standard neutrino-electron interactions (NSI), ...

  9. The photon magnetic moment problem revisited

    International Nuclear Information System (INIS)

    The photon magnetic moment for radiation propagating in magnetized vacuum is defined as a pseudotensor quantity, proportional to the external electromagnetic field tensor. After expanding the eigenvalues of the polarization operator in powers of k2, we obtain approximate dispersion equations (cubic in k2), and analytic solutions for the photon magnetic moment, valid for low momentum and/or large magnetic field. The paramagnetic photon experiences a redshift, with opposite sign to the gravitational one, which differs for parallel and perpendicular polarizations. It is due to the drain of photon transverse momentum and energy by the external field. By defining an effective transverse momentum, the constancy of the speed of light orthogonal to the field is guaranteed. We conclude that the propagation of the photon non-parallel to the magnetic direction behaves as if there is a quantum compression of the vacuum or a warp of space-time in an amount depending on its angle with regard to the field. (orig.)

  10. DMPD: TLR signalling and activation of IRFs: revisiting old friends from the NF-kappaBpathway. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16006187 TLR signalling and activation of IRFs: revisiting old friends from the NF-...nalling and activation of IRFs: revisiting old friends from the NF-kappaBpathway. PubmedID 16006187 Title TL...R signalling and activation of IRFs: revisiting old friends from the NF-kappaBpat

  11. Ornithogalum virens as a plant assay for beta and gamma radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Herron, V J

    1979-01-01

    The purpose of this study was to determine if the monocotyledonous angiosperm, Ornithogalum virens (Quintanilha and Cabral, 1947), could be used in such a biological assay system. After exposing O. virens plants to acute (/sup 60/Co) and chronic (/sup 137/Cs) gamma radiation and internal beta radiation (/sup 32/P), lethality (LD/sub 50/, LD/sub 100/), growth inhibition, and chromosome aberrations were investigated. The LD/sub 50/ and LD/sub 100/ for acute gamma radiation were estimated to be between 0.91 to 1.8 krad and less than 3.6 krad, respectively. Though growth inhibition and abnormal growth were observed in the acute and chronic gamma radiation studies, the changes in the growth of the plants were so variable that these parameters were found to be unreliable measures of radiation effects. Chromosome aberrations were a more reliable measure of radiation damage because linear relationships between total aberrations and dose were found for both gamma and beta radiation.

  12. Process and pattern in cichlid radiations - inferences for understanding unusually high rates of evolutionary diversification.

    Science.gov (United States)

    Seehausen, Ole

    2015-07-01

    The cichlid fish radiations in the African Great Lakes differ from all other known cases of rapid speciation in vertebrates by their spectacular trophic diversity and richness of sympatric species, comparable to the most rapid angiosperm radiations. I review factors that may have facilitated these radiations and compare these with insights from recent work on plant radiations. Work to date suggests that it was a coincidence of ecological opportunity, intrinsic ecological versatility and genomic flexibility, rapidly evolving behavioral mate choice and large amounts of standing genetic variation that permitted these spectacular fish radiations. I propose that spatially orthogonal gradients in the fit of phenotypes to the environment facilitate speciation because they allow colonization of alternative fitness peaks during clinal speciation despite local disruptive selection. Such gradients are manifold in lakes because of the interaction of water depth as an omnipresent third spatial dimension with other fitness-relevant variables. I introduce a conceptual model of adaptive radiation that integrates these elements and discuss its applicability to, and predictions for, plant radiations. PMID:25983053

  13. Revisiting satellite derived tropospheric NO2 trends

    Science.gov (United States)

    Richter, Andreas; Hilboll, Andreas; Burrows, John P.

    2015-04-01

    Nitrogen dioxide levels can be used as tracer of anthropogenic pollution as NOx, the sum of NO and NO2, is released during fossil fuel combustion. With its short atmospheric lifetime, atmospheric NO2 can be easily linked to its sources. Using its structured absorption cross section in the blue spectral region, NO2 amounts can be derived from measurements of backscattered solar radiation with the help of Differential Optical Absorption Spectroscopy measurements. Satellite retrievals of tropospheric NO2 became possible with the launch of the GOME instrument in 1995, and since then a series of instruments including SCIAMACHY, GOME-2 and OMI provide spectral data which can be used to quantify NO2 columns in the troposphere. Using these observations, spatial distributions of NO2, its sources and transport pathways as well as temporal changes have been investigated over the last years. In particular the latter have shown remarkable atmospheric developments with large reductions of NO2 levels in many industrialised countries and dramatic increases in regions with growing economies, most notably in China but also in many other countries. In this study, recent trends of satellite derived NO2 columns are evaluated using data from all available instruments with a focus on the last years. Combination of data taken from the two GOME-2 instruments and OMI improves coverage and sensitivity, and also provides important constraints on the reliability of the satellite data set. As in previous studies, large changes in NO2 columns are found in many regions, in particular over China where after two years of stagnating NO2 levels an unexpected substantial reduction is observed for 2014.

  14. Radiation Protection

    Science.gov (United States)

    ... Radiation Dose & Risk Low-Activity Radioactive Waste Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) Contact Us to ask a question, provide feedback, or report a problem. Main menu Learn the Issues Air Chemicals and ...

  15. Radiation Therapy

    Science.gov (United States)

    ... goal of causing less harm to the surrounding healthy tissue. You don't have to worry that you'll glow in the dark after radiation treatment: People who receive external radiation are not radioactive. You' ...

  16. Medical radiation

    International Nuclear Information System (INIS)

    This leaflet in the At-a-Glance Series describes the medical use of X-rays, how X-rays help in diagnosis, radiation protection of the patient, staff protection, how radioactive materials in nuclear medicine examinations help in diagnosis and the use of radiation in radiotherapy. Magnetic resonance imaging, a diagnostic technique involving no ionizing radiation, is also briefly examined. The role of the NRPB in the medical use of radiation is outlined. (UK)

  17. Semiclassical approach for the evaporating black hole revisited

    Science.gov (United States)

    Gim, Yongwan; Kim, Wontae

    2016-01-01

    A recent calculation shows that the observed energy density in the Unruh state at the future event horizon as seen by a freely falling observer is finite if the observer is released from rest at any positive distance outside the horizon; however, it is getting larger and larger so that it is negatively divergent at the horizon in the limit that the observer starts falling from rest at the horizon, which corresponds to the infinite boost with respect to the freely falling observer at a finite distance from the horizon. In order to resolve some conflicts between the recent calculation and the conventional ones in the well-known literatures, the calculation of the free-fall energy density is revisited and some differences are pointed out.

  18. Threshold Corrections to the Bottom Quark Mass Revisited

    CERN Document Server

    Anandakrishnan, Archana; Raby, Stuart

    2014-01-01

    Threshold corrections to the bottom quark mass are often estimated under the approximation that tan$\\beta$ enhanced contributions are the most dominant. In this work we revisit this common approximation made to the estimation of the supersymmetric threshold corrections to the bottom quark mass. We calculate the full one-loop supersymmetric corrections to the bottom quark mass and survey a large part of the phenomenological MSSM parameter space to study the validity of considering only the tan$\\beta$ enhanced corrections. Our analysis demonstrates that this approximation severely breaks down in parts of the parameter space. The size of the threshold corrections has significant consequences for the estimation of fits to the bottom quark mass, couplings to Higgses, and flavor observables, and therefore the approximate expressions must be replaced with the full contributions for accurate estimations.

  19. Energy in synthetic fertilizers and pesticides: Revisited. Final project report

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, M.G.; English, B.C.; Turhollow, A.F.; Nyangito, H.O. [Tennessee Univ., Knoxville, TN (United States). Dept. of Agricultural Economics and Rural Sociology

    1994-01-01

    Agricultural chemicals that are derived from fossil-fuels are the major energy intensive inputs in agriculture. Growing scarcity of the world`s fossil resources stimulated research and development of energy-efficient technology for manufacturing these chemicals in the last decade. The purpose of this study is to revisit the energy requirements of major plant nutrients and pesticides. The data from manufacturers energy survey conducted by The Fertilizer Institute are used to estimate energy requirements of fertilizers. Energy estimates for pesticides are developed from consulting previously published literature. The impact of technical innovation in the fertilizer industry to US corn, cotton, soybean and wheat producers is estimated in terms of energy-saving.

  20. Revisiting Numerical Pattern Mining with Formal Concept Analysis

    CERN Document Server

    Kaytoue, Mehdi; Napoli, Amedeo

    2011-01-01

    In this paper, we investigate the problem of mining numerical data in the framework of Formal Concept Analysis. The usual way is to use a scaling procedure --transforming numerical attributes into binary ones-- leading either to a loss of information or of efficiency, in particular w.r.t. the volume of extracted patterns. By contrast, we propose to directly work on numerical data in a more precise and efficient way, and we prove it. For that, the notions of closed patterns, generators and equivalent classes are revisited in the numerical context. Moreover, two original algorithms are proposed and used in an evaluation involving real-world data, showing the predominance of the present approach.

  1. Revisiting symmetries of lattice fermions via spin-flavor representation

    CERN Document Server

    Kimura, Taro; Misumi, Tatsuhiro; Noumi, Toshifumi; Torii, Shingo; Aoki, Sinya

    2011-01-01

    Employing the spin-flavor representation, we unveil the structures of the doubler-mixing symmetries and the mechanisms of their spontaneous breakdown in four types of lattice fermion formulation. We first revisit the naive fermion with the vanishing bare mass $m$, and identify the generators of the symmetries which form U(4)$\\times$U(4). The strong-coupling analysis shows that it is broken to U(4) by chiral condensation. We apply the same procedure to the Wilson fermion, which possesses only the U(1) vector symmetry for general values of $m$. For a special value of $m$, however, there emerges an additional U(1) symmetry to be broken by pion condensation. We also explore two types of minimally-doubled fermion, and discover a similar kind of symmetry enhancement and its spontaneous breakdown.

  2. Theory of magnetohydrodynamic waves: The WKB approximation revisited

    International Nuclear Information System (INIS)

    Past treatments of the eikonal or WKB theory of the propagation of magnetohydrodynamics waves have assumed a strictly isentropic background. IF in fact there is a gradient in the background entropy, then in second order in the WKB ordering, adiabatic fluctuations (in the Lagrangian sense) are not strictly isentropic in the Eulerian sense. This means that in the second order of the WKB expansion, which determines the variation of wave amplitude along rays, the violation of isentropy must be accounted for. The present paper revisits the derivation of the WKB approximation for small-amplitude magnetohydrodynamic waves, allowing for possible spatial variation of the background entropy. The equation of variation of wave amplitude is rederived; it is a bilinear equation which, it turns out, can be recast in the action conservation form. It is shown that this action conservation equation is in fact equivalent to the action conservation law obtained from Lagrangian treatments

  3. Axial Electron Heat Loss From Mirror Devices Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D

    2004-08-16

    An issue of the axial electron heat loss is of a significant importance for mirror-based fusion devices. This problem has been considered in a number of publications but it is still shrouded in misconceptions. In this paper we revisit it once again. We discuss the following issues: (1) Formation of the electron distribution function in the end tank at large expansion ratios; (2) The secondary emission from the end plates and the ways of suppressing it (if needed); (3) Ionization and charge exchange in the presence of neutrals in the end tanks; (4) Instabilities caused by the peculiar shape of the electron distribution function and their possible impact on the electron heat losses; (5) Electron heat losses in the pulsed mode of operation of mirror devices.

  4. Revisiting Neoclassical Growth Theory: A Survey in the Literature

    Directory of Open Access Journals (Sweden)

    Mayank GUPTA

    2015-03-01

    Full Text Available Abstract During the second half of the twentieth century economists have build newer models of economic growth that consider policy influences of growth and divergent outcomes among countries. These models addresses issues concerning economic growth, operation of financial markets, trade policy, government expenditures, and taxation. In this essay we have revisited the interdependence of political and economic institutions, taking the neoclassical growth model of Solow (1956 as a point of departure, which maintains that long run economic growth can be explained by capital accumulation, population growth and technological progress. We first discuss the evolution of the neoclassical school of economics in a historical context, and the role of various institutions in engendering economic growth. Subsequently the role of government spending, political stability, property rights and special interest groups (SIG's affect economic growth have been discussed, and how these institutions can explain different countries to grow at divergent rates and achieve different levels of wealth.

  5. Serotype-specific mortality from invasive Streptococcus pneumoniae disease revisited

    DEFF Research Database (Denmark)

    Martens, Pernille; Worm, Signe Westring; Lundgren, Bettina;

    2004-01-01

    with Streptococcus pneumoniae (pneumococci) causes significant morbidity and mortality. Case series and experimental data have shown that the capsular serotype is involved in the pathogenesis and a determinant of disease outcome. METHODS: Retrospective review of 464 cases of invasive disease among adults diagnosed......Serotype-specific mortality from invasive Streptococcus pneumoniae disease revisited.Martens P, Worm SW, Lundgren B, Konradsen HB, Benfield T. Department of Infectious Diseases 144, Hvidovre University Hospital, DK-2650 Hvidovre, Denmark. pernillemartens@yahoo.com BACKGROUND: Invasive infection...... between 1990 and 2001. Multivariate Cox proportional hazard analysis. RESULTS: After adjustment for other markers of disease severity, we found that infection with serotype 3 was associated with an increased relative risk (RR) of death of 2.54 (95% confidence interval (CI): 1.22-5.27), whereas infection...

  6. Simulation of Two-Way Pushdown Automata Revisited

    Directory of Open Access Journals (Sweden)

    Robert Glück

    2013-09-01

    Full Text Available The linear-time simulation of 2-way deterministic pushdown automata (2DPDA by the Cook and Jones constructions is revisited. Following the semantics-based approach by Jones, an interpreter is given which, when extended with random-access memory, performs a linear-time simulation of 2DPDA. The recursive interpreter works without the dump list of the original constructions, which makes Cook's insight into linear-time simulation of exponential-time automata more intuitive and the complexity argument clearer. The simulation is then extended to 2-way nondeterministic pushdown automata (2NPDA to provide for a cubic-time recognition of context-free languages. The time required to run the final construction depends on the degree of nondeterminism. The key mechanism that enables the polynomial-time simulations is the sharing of computations by memoization.

  7. Gospel, culture and mission: Revisiting an enduring problem

    Directory of Open Access Journals (Sweden)

    O.U. Kalu

    1998-08-01

    Full Text Available Gospel, culture and mission: Revisiting an enduring problem This article reflects on the 1996 Conference on World Mission and Evangelism. The relation between gospel, culture and mission is considered, especially from an Africa perspective, but not reserved to it in application. Apart from considering the problem of appropriate terminology to express the intricacies concerning the subject, a deeper search is conducted into the complex relationship between the believer, his mission to, and his distancing from divergent cultural sources and manifestations. Emerging perspectives are considered, which help to formulate mission strategies and historic viewpoints and attitudes. Knowledge of these perspectives is essential for a more responsible answering to the call made to all believers.

  8. Revisiting constraints on uplifts to de Sitter vacua

    CERN Document Server

    Bizet, Nana Cabo

    2016-01-01

    We revisit the issue of uplifting the potential to de Sitter (dS) vacua in type IIB flux compactifications of Kachru, Kallosh, Linde and Trivedi (KKLT). We shed light on some tension between two constraints on dS vacua in type IIB string theory. One is the well-known and much-discussed constraint which leads to the no-go theorem that can in principle be evaded. The other follows from 4-dimensional Einstein's equations, which has, however, been much less discussed in connection with the former constraint. In addition to the challenges previously posed, it is suggested that the uplifting scenarios, in particular, obstruct the evasion of the no-go theorem more strongly than one might have assumed.

  9. The Safety of Adjuvanted Vaccines Revisited: Vaccine-Induced Narcolepsy.

    Science.gov (United States)

    Ahmed, S Sohail; Montomoli, Emanuele; Pasini, Franco Laghi; Steinman, Lawrence

    2016-01-01

    Despite the very high benefit-to-risk ratio of vaccines, the fear of negative side effects has discouraged many people from getting vaccinated, resulting in the reemergence of previously controlled diseases such as measles, pertussis and diphtheria. This fear has been amplified more recently by multiple epidemiologic studies that confirmed the link of an AS03-adjuvanted pandemic influenza vaccine (Pandemrix, GlaxoSmithKline Biologicals, Germany) used in Europe during the 2009 H1N1 influenza pandemic [A(H1N1) pdm09] with the development of narcolepsy, a chronic sleep disorder, in children and adolescents. However, public misperceptions of what adjuvants are and why they are used in vaccines has created in some individuals a closed "black box" attitude towards all vaccines. The focus of this review article is to revisit this "black box" using the example of narcolepsy associated with the European AS03-adjuvanted pandemic influenza vaccine. PMID:27228647

  10. Revisiting world energy intensity convergence for regional differences

    Energy Technology Data Exchange (ETDEWEB)

    Liddle, Brantley [Centre for Strategic Economic Studies, Victoria University, Melbourne, VIC 8001 (Australia)

    2010-10-15

    World convergence in energy intensity is revisited using two new large data sets: a 111-country sample spanning 1971-2006, and a 134-country sample spanning 1990-2006. Both data sets confirm continued convergence. However, the larger data set, which adds the former Soviet Union republics and additional Balkan countries, indicates greater convergence over its more recent time-frame. Further investigation of geographical differences reveals that the OECD and Eurasian countries have shown considerable, continued convergence, while the Sub-Saharan African countries have converged amongst themselves, but at a slower rate than the OECD and Eurasian countries; by contrast, Latin American and Caribbean and Middle East and North African countries have exhibited no convergence to divergence in energy intensity. (author)

  11. Revisiting time reversal and holography with spacetime transformations

    CERN Document Server

    Bacot, Vincent; Eddi, Antonin; Fink, Mathias; Fort, Emmanuel

    2015-01-01

    Wave control is usually performed by spatially engineering the properties of a medium. Because time and space play similar roles in wave propagation, manipulating time boundaries provides a complementary approach. Here, we experimentally demonstrate the relevance of this concept by introducing instantaneous time mirrors. We show with water waves that a sudden change of the effective gravity generates time-reversed waves that refocus at the source. We generalize this concept for all kinds of waves introducing a universal framework which explains the effect of any time disruption on wave propagation. We show that sudden changes of the medium properties generate instant wave sources that emerge instantaneously from the entire space at the time disruption. The time-reversed waves originate from these "Cauchy sources" which are the counterpart of Huygens virtual sources on a time boundary. It allows us to revisit the holographic method and introduce a new approach for wave control.

  12. Crop Classification Using Short-Revisit Multitemporal SAR Data

    DEFF Research Database (Denmark)

    Skriver, Henning; Mattia, Francesco; Satalino, Giuseppe; Balenzano, Anna; Pauwels, Valentijn R. N.; Verhoest, Niko E. C.; Davidson, Malcolm

    2011-01-01

    Classification of crops and other land cover types is an important application of both optical/infrared and SAR satellite data. It is already an import application of present satellite systems, as it will be for planned missions, such as the Sentinels. An airborne SAR data set with a short revisit...... time acquired by the German ESAR system during the ESA-campaign, AgriSAR 2006, has been used to assess the performance of different polarization modes for crop classification. Both C-and L-band SAR data were acquired over the Demmin agricultural test site in North Eastern Germany on a weekly basis...... during the growing season. Single-and dual-polarization, and fully polarimetric data have been used in the analysis (fully polarimetric data were only available at L-band). The main results of the analysis are, that multitemporal acquisitions are very important for single-and dual-polarization modes, and...

  13. Ionizing radiation

    International Nuclear Information System (INIS)

    The subject is discussed under the headings: characteristics of ionizing radiations; biological effects; comparison of radiation and other industrial risks; principles of protection; cost-benefit analysis; dose limits; the control and monitoring of radiation; reference levels; emergency reference levels. (U.K.)

  14. The introduction of Superluminal Lorentz transformations: A revisitation

    Science.gov (United States)

    Maccarrone, G. D.; Recami, Erasmo

    1984-05-01

    We revisit the introduction of the Superluminal Lorentz transformations which carry from “bradyonic” inertial frames to “tachyonic” inertial frames, i.e., which transform time-like objects into space-like objects, and vice versa. It has long been known that special relativity can be extended to Superluminal observers only by increasing the number of dimensions of the space-time or—which is in a sense equivalent—by releasing the reality condition (i.e., introducing also imaginary quantities). In the past we always adopted the latter procedure. Here we show the connection between that procedure and the former one. In other words, in order to clarify the physical meaning of the imaginary units entering the classical theory of tachyons, we have temporarily to call into play an auxiliary six-dimensional space-time M (3, 3); however, we are eventually able to go back to the four-dimensional Minkowski space-time. We revisit the introduction of the Superluminal Lorentz transformations also under another aspect. In fact, the generalized Lorentz transformations had been previously written down in a form suited only for the simple case of collinear boosts (e.g., they formed a group just for collinear boosts). We express now the Superluminal Lorentz transformations in a more general form, so that they constitute a group together with the ordinary—orthochronous and antichronous—Lorentz transformations, and reduce to the previous form in the case of collinear boosts. Our approach introduces either real or imaginary quantities, with exclusion of (generic) complex quantities. In the present context, a procedure—in two steps—for interpreting the imaginary quantities is put forth and discussed. In the case of a chain of generalized Lorentz transformations, such a procedure (when necessary) is to be applied only at the end of the chain. Finally, we justify why we call “transformations” also the Superluminal ones.

  15. Pulsar electrodynamics: Relativistic kinetic theory of radiative plasmas--collective phenomena and their radiation

    International Nuclear Information System (INIS)

    The classical modeling of radiation by accelerated charged particles in pulsars predicts a cutoff in photon energy at around 25 GeV. While this is broadly consistent with observations, the classical treatment is not self-consistent, and cannot be extended to explain the rare high-energy detections of photons in the 100s of GeV range. In this paper we revisit the theoretical modeling of high-energy radiation processes in very strong electromagnetic fields, in the context of both single particles and collective plasmas. There are no classical constraints on this description. We find that there is indeed a critical energy of around 50 GeV that arises naturally in this self-consistent treatment, but rather than being a cutoff, this critical energy signals a transition from radiation that is classical to a quasiquantum description, in which the particle is able to radiate almost its total energy in a single event. This new modeling therefore places pulsar radiation processes on a more secure physical basis, and admits the possibility of the production of TeV photons in a self-consistent way.

  16. Ionizing radiations

    International Nuclear Information System (INIS)

    The purpose of this article is to simplify some of the relevant points of legislation, biological effects and protection for the benefit of the occupational health nurse not familiar with the nuclear industries. The subject is dealt with under the following headings; Understanding atoms. What is meant by ionizing radiation. Types of ionizing radiation. Effects of radiation: long and short term somatic effects, genetic effects. Control of radiation: occupational exposure, women of reproductive age, medical aspects, principles of control. The occupational health nurse's role. Emergency arrangements: national arrangements for incidents involving radiation, action to be taken by the nurse. Decontamination procedures: external and internal contamination. (U.K.)

  17. On the thermodynamic origin of the initial radiation energy density in warm inflation

    CERN Document Server

    Gim, Yongwan

    2016-01-01

    In warm inflation scenarios, radiation always exists, so that the radiation energy density is also assumed to be finite when inflation starts. To find out the origin of the non-vanishing initial radiation energy density, we revisit thermodynamic analysis for a warm inflation model and then derive an effective Stefan-Boltzmann law which is commensurate with the temperature-dependent effective potential by taking into account the non-vanishing trace of the total energy-momentum tensors. The effective Stefan-Boltzmann law shows that the zero energy density for radiation at the Grand Unification epoch increases until the inflation starts and it becomes eventually finite at the initial stage of warm inflation. By using the above effective Stefan-Boltzmann law, we also study the cosmological scalar perturbation, and obtain the sufficient radiation energy density in order for GUT baryogenesis at the end of inflation.

  18. The problem of multicollinearity in horizontal solar radiation estimation models and a new model for Turkey

    International Nuclear Information System (INIS)

    Highlights: • Impacts of multicollinearity on solar radiation estimation models are discussed. • Accuracy of existing empirical models for Turkey is evaluated. • A new non-linear model for the estimation of average daily horizontal global solar radiation is proposed. • Estimation and prediction performance of the proposed and existing models are compared. - Abstract: Due to the considerable decrease in energy resources and increasing energy demand, solar energy is an appealing field of investment and research. There are various modelling strategies and particular models for the estimation of the amount of solar radiation reaching at a particular point over the Earth. In this article, global solar radiation estimation models are taken into account. To emphasize severity of multicollinearity problem in solar radiation estimation models, some of the models developed for Turkey are revisited. It is observed that these models have been identified as accurate under certain multicollinearity structures, and when the multicollinearity is eliminated, the accuracy of these models is controversial. Thus, a reliable model that does not suffer from multicollinearity and gives precise estimates of global solar radiation for the whole region of Turkey is necessary. A new nonlinear model for the estimation of average daily horizontal solar radiation is proposed making use of the genetic programming technique. There is no multicollinearity problem in the new model, and its estimation accuracy is better than the revisited models in terms of numerous statistical performance measures. According to the proposed model, temperature, precipitation, altitude, longitude, and monthly average daily extraterrestrial horizontal solar radiation have significant effect on the average daily global horizontal solar radiation. Relative humidity and soil temperature are not included in the model due to their high correlation with precipitation and temperature, respectively. While altitude has

  19. Atoms, Radiation, and Radiation Protection

    CERN Document Server

    Turner, James E

    2007-01-01

    Atoms, Radiation, and Radiation Protection offers professionals and advanced students a comprehensive coverage of the major concepts that underlie the origins and transport of ionizing radiation in matter. Understanding atomic structure and the physical mechanisms of radiation interactions is the foundation on which much of the current practice of radiological health protection is based. The work covers the detection and measurement of radiation and the statistical interpretation of the data. The procedures that are used to protect man and the environment from the potential harmful effects of

  20. Radiation dosimetry and radiation biophysics

    International Nuclear Information System (INIS)

    Radiation dosimetry and radiation biophysics are two closely integrated programs whose joint purpose is to explore the connections between the primary physical events produced by radiation and their biological consequences in cellular systems. The radiation dosimetry program includes the theoretical description of primary events and their connection with the observable biological effects. This program also is concerned with the design and measurement of physical parameters used in theory or to support biological experiments. The radiation biophysics program tests and uses the theoretical developments for experimental design, and provides information for further theoretical development through experiments on cellular systems

  1. Radiation dosimetry and radiation biophysics

    International Nuclear Information System (INIS)

    Radiation dosimetry and radiation biophysics are two closely integrated programs whose joint purpose is to explore the connections between the primary physical events produced by radiation and their biological consequences in cellular systems. The radiation dosimetry program includes the theoretical description of primary events and their connection with the observable biological effects. This program also is concerned with design and measurement of those physical parameters used in the theory or to support biological experiments. The radiation biophysics program tests and makes use of the theoretical developments for experimental design. Also, this program provides information for further theoretical development through experiments on cellular systems

  2. Radiation Chemistry

    Science.gov (United States)

    Wojnárovits, L.

    Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

  3. Radiation acoustics

    CERN Document Server

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  4. Radiation injury

    International Nuclear Information System (INIS)

    Radiation accidents and incidents continue to be of great interest and concern to the public. Issues such as the threat of nuclear war, the Chernobyl reactor accident, or reports of sporadic incidences of accidental radiation exposure keep this interest up and maintain a high level of fear among the public. In this climate of real concern and radiation phobia, physicians should not only be prepared to answer questions about acute or late effects of ionizing radiation, but also be able to participate in the initial assessment and management of individuals who have been exposed to ionizing radiation or contaminated with radioactive material. Some of the key facts about radiation injury and its medical treatment are discussed by the author

  5. Radiation damage in bioapatites: the ESR spectrum of irradiated dental enamel revisited

    International Nuclear Information System (INIS)

    We have studied the ESR spectrum of enamel from fossil vertebrate teeth perpendicular = 2.0026 and glongitudinal = 1.9975; and species B, having an orthorhombic symmetry with g1 = 2.0032, g2 = 2.0018 and g3 = 1.9975. Center A is probably located at an OH- site of the hydroxyapatite lattice. Centre B could be a distorted centre A. (author)

  6. Revisiting radiation patterns in e{sup +}e{sup -} collisions

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, N.; Gieseke, S. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Theoretische Physik; Plaetzer, S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Skands, P. [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-02-15

    We propose four simple event-shape variables for semi-inclusive e{sup +}e{sup -}→4-jet events. The observables and cuts are designed to be especially sensitive to subleading aspects of the event structure, and allow to test the reliability of phenomenological QCD models in greater detail. Three of them, θ{sub 14}, θ{sup *}, and C{sup (1/5)}{sub 2}, focus on soft emissions off three-jet topologies with a small opening angle, for which coherence effects beyond the leading QCD dipole pattern are expected to be enhanced. A complementary variable, M{sup 2}{sub L}/M{sup 2}{sub H}, measures the ratio of the hemisphere masses in 4-jet events with a compressed scale hierarchy (Durham y{sub 23}∝y{sub 34}), for which subleading 1→3 splitting effects are expected to be enhanced. We consider several different parton-shower models, spanning both conventional and dipole/antenna ones, all tuned to the same e{sup +}e{sup -} reference data, and show that a measurement of the proposed observables would allow for additional significant discriminating power between the models.

  7. Hawking radiation

    Science.gov (United States)

    Parentani, Renaud; Spindel, Philippe

    2011-12-01

    Hawking radiation is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole horizon. It is named after the physicist Stephen Hawking who derived its existence in 1974. This radiation reduces the mass of black holes and is therefore also known as black hole evaporation.

  8. Radiation regulation

    International Nuclear Information System (INIS)

    The five main areas of radiation regulation considered are radiation exposure in the mining of uranium and other minerals, exposure in the use of uranium in nuclear reactors, risks in the transport of radioactive materials and hazards associated with the disposal of used materials. In Australia these problems are regulated by mines departments, the Australian Atomic Energy Commission and radiation control branches in state health departments. Each of these instutional areas of regulation is examined

  9. GRAVITATIONAL RADIATION

    OpenAIRE

    SALTIK, Metin; Mustafa KURT; Mehmet KAYMAK

    1996-01-01

    According to classical electromagnetic theory, an accelerated charge or system of charges radiates electromagnetic waves. In a radio transmitter antenna charges are accelerated along the antenna and release electromagnetic waves, which is radiated at the velocity of light in the surrounding medium. All of the radio transmitters work on this principle today. In this study an analogy is established between the principles by which accelerated charge systems markes radiation and the accelerated m...

  10. Plume radiation

    Science.gov (United States)

    Dirscherl, R.

    1993-06-01

    The electromagnetic radiation originating from the exhaust plume of tactical missile motors is of outstanding importance for military system designers. Both missile- and countermeasure engineer rely on the knowledge of plume radiation properties, be it for guidance/interference control or for passive detection of adversary missiles. To allow access to plume radiation properties, they are characterized with respect to the radiation producing mechanisms like afterburning, its chemical constituents, and reactions as well as particle radiation. A classification of plume spectral emissivity regions is given due to the constraints imposed by available sensor technology and atmospheric propagation windows. Additionally assessment methods are presented that allow a common and general grouping of rocket motor properties into various categories. These methods describe state of the art experimental evaluation techniques as well as calculation codes that are most commonly used by developers of NATO countries. Dominant aspects influencing plume radiation are discussed and a standardized test technique is proposed for the assessment of plume radiation properties that include prediction procedures. These recommendations on terminology and assessment methods should be common to all employers of plume radiation. Special emphasis is put on the omnipresent need for self-protection by the passive detection of plume radiation in the ultraviolet (UV) and infrared (IR) spectral band.

  11. Radiation medicine

    International Nuclear Information System (INIS)

    This booklet has been produced by UKAEA and the Marie Curie Memorial Foundation to give some basic information about what radiation is and how it is used in day to day diagnosis and treatment. It will be of interest to people undergoing treatment, their relatives and friends, and anyone who wants to know more about this important area. After a brief historical introduction the booklet explains what radiation is, the natural and man-made sources of radiation, how it is produced and how X-rays are used in medical diagnosis and treatment. The radiation protection measures taken and safety standards followed are mentioned. (author)

  12. GRAVITATIONAL RADIATION

    Directory of Open Access Journals (Sweden)

    Metin SALTIK

    1996-03-01

    Full Text Available According to classical electromagnetic theory, an accelerated charge or system of charges radiates electromagnetic waves. In a radio transmitter antenna charges are accelerated along the antenna and release electromagnetic waves, which is radiated at the velocity of light in the surrounding medium. All of the radio transmitters work on this principle today. In this study an analogy is established between the principles by which accelerated charge systems markes radiation and the accelerated mass system, and the systems cousing gravitational radiation are investigated.

  13. Radiation protection

    International Nuclear Information System (INIS)

    A NRPB leaflet in the 'At-a-Glance' series explains in a simple but scientifically accurate way what radiation is, the biological effects and the relative sensitivity of different parts of the human body. The leaflet then discusses radiation protection principles, radiation protection in the UK and finally the effectiveness of this radiation protection as judged by a breakdown of the total dose received by an average person in the UK, a heavy consumer of Cumbrian seafood, an average nuclear industry worker and an average person in Cornwall. (UK)

  14. Radiation roulette

    International Nuclear Information System (INIS)

    Radiation biologists at the Medical Research Council, now argue that radiation exposure may cause a much wider range of diseases than epidemiological studies currently predict, with effects being felt well below the 1 millisievert a year public safety levels enforce at present. A fourth outcome for ionizing radiation affecting a living cell has recently been identified, whereby DNA damage to cells can only be detected after they have divided several times, so-called radiation-induced genomic instability. Initial results have been confirmed internationally, but interpretations differ, with some scientists dismissing the connection between genomic instability and disease causation. (UK)

  15. Radiation roulette

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, R.

    1997-10-11

    Radiation biologists at the Medical Research Council, now argue that radiation exposure may cause a much wider range of diseases than epidemiological studies currently predict, with effects being felt well below the 1 millisievert a year public safety levels enforce at present. A fourth outcome for ionizing radiation affecting a living cell has recently been identified, whereby DNA damage to cells can only be detected after they have divided several times, so-called radiation-induced genomic instability. Initial results have been confirmed internationally, but interpretations differ, with some scientists dismissing the connection between genomic instability and disease causation. (UK).

  16. A copal-8-ol diphosphate synthase from the angiosperm Cistus creticus subsp. creticus is a putative key enzyme for the formation of pharmacologically active, oxygen-containing labdane-type diterpenes.

    Science.gov (United States)

    Falara, Vasiliki; Pichersky, Eran; Kanellis, Angelos K

    2010-09-01

    The resin of Cistus creticus subsp. creticus, a plant native to Crete, is rich in labdane-type diterpenes with significant antimicrobial and cytotoxic activities. The full-length cDNA of a putative diterpene synthase was isolated from a C. creticus trichome cDNA library. The deduced amino acid sequence of this protein is highly similar (59%-70% identical) to type B diterpene synthases from other angiosperm species that catalyze a protonation-initiated cyclization. The affinity-purified recombinant Escherichia coli-expressed protein used geranylgeranyl diphosphate as substrate and catalyzed the formation of copal-8-ol diphosphate. This diterpene synthase, therefore, was named CcCLS (for C. creticus copal-8-ol diphosphate synthase). Copal-8-ol diphosphate is likely to be an intermediate in the biosynthesis of the oxygen-containing labdane-type diterpenes that are abundant in the resin of this plant. RNA gel-blot analysis revealed that CcCLS is preferentially expressed in the trichomes, with higher transcript levels found in glands on young leaves than on fully expanded leaves, while CcCLS transcript levels increased after mechanical wounding. Chemical analyses revealed that labdane-type diterpene production followed a similar pattern, with higher concentrations in trichomes of young leaves and increased accumulation upon wounding. PMID:20595348

  17. Synchrotron radiation

    International Nuclear Information System (INIS)

    The paper on Synchrotron Radiation contains the appendix to the Daresbury Annual Report 1987/88. The appendix is mainly devoted to the scientific progress reports on the work at the Synchrotron Radiation Source in 1987/8. The parameters of the Experimental Stations and the index to the Scientific Reports are also included in the appendix. (U.K.)

  18. Radiation hematology

    International Nuclear Information System (INIS)

    State-of-the-Art ofl radiation hematology and review of the problems now facing this brauch of radiobiology and nuclear medicine are presented. Distortion of division and maturation of hemopoiesis parent cells is considered as main factor of radiopathology for hematopoetic system. Problems of radiation injury and functional variation of hematopoetic microenvironment cell populations are discussed. 176 figs.; 23 figs.; 18 tabs

  19. Radiation signatures

    International Nuclear Information System (INIS)

    A new concept for modelling radiation risk is proposed. This concept is based on the proposal that the spectrum of molecular lesions, which we dub ''the radiation signature'', can be used to identify the quality of the causal radiation. If the proposal concerning radiation signatures can be established then, in principle, both prospective and retrospective risk determination can be assessed on an individual basis. A major goal of biophysical modelling is to relate physical events such as ionization, excitation, etc. to the production of radiation carcinogenesis. A description of the physical events is provided by track structure. The track structure is determined by radiation quality, and it can be considered to be the ''physical signature'' of the radiation. Unfortunately, the uniqueness characteristics of this signature are dissipated in biological systems in ∼10-9s. Nonetheless, it is our contention that this physical disturbance of the biological system eventuates later, at ∼100s, in molecular lesion spectra which also characterize the causal radiation. (author)

  20. Radiation oncology

    International Nuclear Information System (INIS)

    The Radiation Oncology Division has had as its main objectives both to operate an academic training program and to carry out research on radiation therapy of cancer. Since fiscal year 1975, following a directive from ERDA, increased effort has been given to research. The research activities have been complemented by the training program, which has been oriented toward producing radiation oncologists, giving physicians short-term experience in radiation oncology, and teaching medical students about clinical cancer and its radiation therapy. The purpose of the research effort is to improve present modalities of radiation therapy of cancer. As in previous years, the Division has operated as the Radiation Oncology Program of the Department of Radiological Sciences of the University of Puerto Rico School of Medicine. It has provided radiation oncology support to patients at the University Hospital and to academic programs of the University of Puerto Rico Medical Sciences Campus. The patients, in turn, have provided the clinical basis for the educational and research projects of the Division. Funding has been primarily from PRNC (approx. 40%) and from National Cancer Institute grants channeled through the School of Medicine (approx. 60%). Special inter-institutional relationships with the San Juan Veterans Administration Hospital and the Metropolitan Hospital in San Juan have permitted inclusion of patients from these institutions in the Division's research projects. Medical physics and radiotherapy consultations have been provided to the Radiotherapy Department of the VA Hospital

  1. Concepts of radiation protection

    International Nuclear Information System (INIS)

    This seventh chapter presents the concepts and principles of safety and radiation protection, emergency situations; NORM and TENORM; radiation protection care; radiation protection plan; activities of the radiation protection service; practical rules of radiation protection and the radiation symbol

  2. Medical radiation

    International Nuclear Information System (INIS)

    Three slide sets which can be used in lectures about radiation protection have been published by NRPB. The slide sets are based on publications in the NRPB ''At-a-Glance'' series of broadsheets, which use illustrations as the main source of information, supported by captions; the series generally avoids the jargon of radiation protection, although each leaflet is based on scientific studies. Slide Set Number 3, ''Medical Radiation'', outlines the production and use of x-rays in diagnosis, the protection of staff and patients, and the use of radioactive materials in diagnosis and radiotherapy. It summarises the use of magnetic resonance imaging. Radiation doses received during various x-ray examinations are compared with radiation doses from nature. (Author)

  3. Radiation carcinogenesis

    International Nuclear Information System (INIS)

    Studies on neutron carcinogenesis, time-dose relationships, the role of host factors in radiation carcinogenesis, and the dynamics of the carcinogenic process after exposure to radiation and chemicals are reported. Problems are being pursued with in vivo studies as well as in vitro and in vivo/in vitro approaches. A common theme among all of these studies is the examination of mechanisms and the establishment of general principles which may alow a better understanding of the risks to humans from radiation exposure. Data from all of these studies are also being used to examine more direct methods of extrapolation of animal data to human risks. The program in ultraviolet radiation carcinogenesis (UVR) is concerned with development of model systems, methods and background information necessary for designing quantitative UVR carcinogenesis experiments, the role of interactions of UVR and chemicals, and interactions between ionizing and ultraviolet radiation in skin carcinogenesis

  4. Radiation detector

    Science.gov (United States)

    Fultz, Brent T.

    1983-01-01

    Apparatus is provided for detecting radiation such as gamma rays and X-rays generated in backscatter Mossbauer effect spectroscopy and X-ray spectrometry, which has a large "window" for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  5. Radiation sickness

    International Nuclear Information System (INIS)

    The frequency of radiation sickness in 1,060 patients treated at our Department was 12.8 percent. It was frequent in patients with brain cancer (12 percent), whole spine cancer (47 percent), uterus cancer (28 percent), lung cancer (22 percent) and esophagus cancer (12 percent). Radiation sickness following X-irradiation was studied in its relation to patient's age, size of radiation fields, dosis and white blood cell count. However, we could not find any definite clinical feature relevant to occurrence. There are many theories published concerning the mechanism of radiation sickness. Clinical experiences have shown that radiation sickness cannot be explained by one theory alone but by several theories such as those based on psychology, stress or histamine. (author)

  6. Polarization in cyclotron radiation in strong magnetic fields

    Institute of Scientific and Technical Information of China (English)

    Luidmila Semionova; Denis Leahy; Jorge Paez

    2010-01-01

    We revisit the problem of radiative transitions of electrons in the presence of a strong magnetic field.We derive fully relativistic cyclotron transition rates for an arbitrary magnetic field,for any orientation of electron spin and for any polarization of the emitted radiation.Also,we obtain the transition rates for any value of the initial electron's parallel momentum.For very strong magnetic fields,transitions to the ground state predominate.Transition rates summed over the electron's spin orientation and for unpolarized radiation are also obtained,which confirm previous results by Latal.Transition widths are calculated for different electron spin orientations and different polarizations of radiation.We obtain general expressions for transition rates that reduce to the results for the non-relativistic case and for unpolarized radiation.Additionally we get,for the non-relativistic approximation,the transition rates for any polarization of radiation.As an application,the first five emission lines are evaluated and compared to the X-ray emitting neutron star V0332+53,which has multiple observable cyclotron lines,taking into account gravitational redshift.The most probable polarization is ∈(2).

  7. A critical review of the system of radiation protection

    International Nuclear Information System (INIS)

    Our modern, information society is increasingly interested in transparency and participation in many aspects of government, and this is particularly true in areas involving public health and environmental protection. Radiation protection is no exception to this trend. Scientific rationale that was once sufficient to explain radiation protection theory and practice is no longer adequate. The need to address and communicate theory, practice and the decision-making process to a wider audience has given rise to numerous debates and led the radiation protection community to revisit the framework of the system of radiation protection. The very fundamentals of the system of radiation protection continue to be questioned in a healthy fashion, and many aspects have been identified which could better serve stakeholders given some additional thought in the light of modern societal needs. This report is the summary of the NEA's first reflections in this area, and describes those aspects of the current international system of radiation protection that could be improved. Suggested directions for improvement are provided. (author)

  8. Polarization in cyclotron radiation in strong magnetic fields

    International Nuclear Information System (INIS)

    We revisit the problem of radiative transitions of electrons in the presence of a strong magnetic field. We derive fully relativistic cyclotron transition rates for an arbitrary magnetic field, for any orientation of electron spin and for any polarization of the emitted radiation. Also, we obtain the transition rates for any value of the initial electron's parallel momentum. For very strong magnetic fields, transitions to the ground state predominate. Transition rates summed over the electron's spin orientation and for unpolarized radiation are also obtained, which confirm previous results by Latal. Transition widths are calculated for different electron spin orientations and different polarizations of radiation. We obtain general expressions for transition rates that reduce to the results for the non-relativistic case and for unpolarized radiation. Additionally we get, for the non-relativistic approximation, the transition rates for any polarization of radiation. As an application, the first five emission lines are evaluated and compared to the X-ray emitting neutron star V0332+53, which has multiple observable cyclotron lines, taking into account gravitational redshift. The most probable polarization is in(2). (research papers)

  9. Influence of ion mass on laser-energy absorption and synchrotron radiation at ultrahigh laser intensities

    International Nuclear Information System (INIS)

    The role of ions in the energy absorption of a short and ultra intense laser pulse and in the synchrotron radiation generated by accelerated electrons is revisited. For laser intensities above 1022 W/cm2 and plasma densities more than 10 times the critical density, the ion-to-electron mass ratio strongly affects the energy repartition between the electrons, ions, and radiation. This phenomenon is studied with a one dimensional relativistic particle-in-cell code, taking into account the radiation reaction force. The choice of the ion mass strongly affects the energy and angular distribution of the photon emission and the electron energy distribution. This effect may be important for laboratory modeling of radiation dominated relativistic astrophysical events. It can be verified in experiments with solid hydrogen targets. (authors)

  10. Changes in Sea Levels around the British Isles Revisited (Invited)

    Science.gov (United States)

    Teferle, F. N.; Hansen, D. N.; Bingley, R. M.; Williams, S. D.; Woodworth, P. L.; Gehrels, W. R.; Bradley, S. L.; Stocchi, P.

    2009-12-01

    Recently a number of new and/or updated sources for estimates of vertical land movements for the British Isles have become available allowing the relative and average changes in sea levels for this region to be revisited. The geodetic data set stems from a combination of re-processed continuous Global Positioning System (GPS) measurements from stations in the British Isles and from a global reference frame network, and absolute gravity (AG) measurements from two stations in the British Isles. The geologic data set of late Holocene sea level indicators has recently been updated, now applying corrections for the 20th century sea level rise, syphoning effect and late Holocene global ice melt, and expanded to Northern Ireland and Ireland. Several new model predictions of the glacial isostatic adjustment (GIA) process active in this region form the modelling data set of vertical land movements for the British Isles. Correcting the updated revised local reference (RLR) trends from the Permanent Service for Mean Sea Level (PSMSL) with these vertical land movement data sets, regional and averaged changes in sea levels around the British Isles have been investigated. Special focus is thereby also given to the coastal areas that have recently been identified within the UK Climate Projections 2009.

  11. V838 Monocerotis revisited: Space phenomenon imitates art

    Science.gov (United States)

    2004-03-01

    V838 Monocerotis revisited: Space phenomenon imitates art hi-res Size hi-res: 558 Kb Credits: NASA, the Hubble Heritage Team (AURA/STScI) and ESA V838 Monocerotis revisited: Space phenomenon imitates art "Starry Night", Vincent van Gogh's famous painting, is renowned for its bold whorls of light sweeping across a raging night sky. Although this image of the heavens came only from the artist's restless imagination, a new picture from the NASA/ESA Hubble Space Telescope bears remarkable similarities to the van Gogh work, complete with never-before-seen spirals of dust swirling across trillions of kilometres of interstellar space. This image, obtained with the Advanced Camera for Surveys on February 8, 2004, is Hubble's latest view of an expanding halo of light around a distant star, named V838 Monocerotis (V838 Mon). The illumination of interstellar dust comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light two years ago. V838 Mon is located about 20,000 light-years away from Earth in the direction of the constellation Monoceros, placing the star at the outer edge of our Milky Way galaxy V838 Monocerotis revisited: Space phenomenon imitates art hi-res Size hi-res: 1989 kb Credits: NASA, the Hubble Heritage Team (AURA/STScI) and ESA V838 Monocerotis revisited: Space phenomenon imitates art "Starry Night", Vincent van Gogh's famous painting, is renowned for its bold whorls of light sweeping across a raging night sky. Although this image of the heavens came only from the artist's restless imagination, a new picture from the NASA/ESA Hubble Space Telescope bears remarkable similarities to the van Gogh work, complete with never-before-seen spirals of dust swirling across trillions of kilometres of interstellar space. This image, obtained with the Advanced Camera for Surveys on February 8, 2004, is Hubble's latest view of an expanding halo of light around a distant star, named V838 Monocerotis (V838 Mon). The

  12. Whistler oscillitons revisited: the role of charge neutrality?

    Directory of Open Access Journals (Sweden)

    F. Verheest

    2004-01-01

    Full Text Available When studying transverse modes propagating parallel to a static magnetic field, an apparent contradiction arises between the weakly nonlinear results obtained from the derivative nonlinear Schrödinger equation, predicting envelope solitons (where the amplitude is stationary in the wave frame, but the phase is not, and recent results for whistler oscillitons, indicating that really stationary structures of large amplitude are possible. Revisiting this problem in the fluid dynamic approach, care has been taken not to introduce charge neutrality from the outset, because this not only neglects electric stresses compared to magnetic stresses, which is reasonable, but could also imply from Poisson's equation a vanishing of the wave electric field. Nevertheless, the fixed points of the remaining equations are the same, whether charge neutrality is assumed from the outset or not, so that the solitary wave solutions at not too large amplitudes will be very similar. This is borne out by numerical simulations of the solutions under the two hypotheses, showing that the lack of correspondence with the DNLS envelope solitons indicates the limitations of the reductive perturbation approach, and is not a consequence of assuming charge neutrality.

  13. Revisiting the Master-Signifier, or, Mandela and Repression.

    Science.gov (United States)

    Hook, Derek; Vanheule, Stijn

    2015-01-01

    The concept of the master-signifier has been subject to a variety of applications in Lacanian forms of political discourse theory and ideology critique. While there is much to be commended in literature of this sort, it often neglects salient issues pertaining to the role of master signifiers in the clinical domain of (individual) psychical economy. The popularity of the concept of the master (or "empty") signifier in political discourse analysis has thus proved a double-edged sword. On the one hand it demonstrates how crucial psychical processes are performed via the operations of the signifier, extending thus the Lacanian thesis that identification is the outcome of linguistic and symbolic as opposed to merely psychological processes. On the other, the use of the master signifier concept within the political realm to track discursive formations tends to distance the term from the dynamics of the unconscious and operation of repression. Accordingly, this paper revisits the master signifier concept, and does so within the socio-political domain, yet while paying particular attention to the functioning of unconscious processes of fantasy and repression. More specifically, it investigates how Nelson Mandela operates as a master signifier in contemporary South Africa, as a vital means of knitting together diverse elements of post-apartheid society, enabling the fantasy of the post-apartheid nation, and holding at bay a whole series of repressed and negated undercurrents. PMID:26834664

  14. Revisiting the master-signifier, or, Mandela and repression

    Directory of Open Access Journals (Sweden)

    Derek eHook

    2016-01-01

    Full Text Available The concept of the master-signifier has been subject to a variety of applications in Lacanian forms of political discourse theory and ideology critique. While there is much to be commended in literature of this sort, it often neglects salient issues pertaining to the role of master signifiers in the clinical domain of (individual psychical economy. The popularity of the concept of the master (or ‘empty’ signifier in political discourse analysis has thus proved a double-edged sword. On the one hand it demonstrates how crucial psychical processes are performed via the operations of the signifier, extending thus the Lacanian thesis that identification is as much the outcome of linguistic and symbolic as opposed to merely psychological processes. On the other, the use of the master signifier concept within the political realm to track discursive formations tends to distance the term from the dynamics of the unconscious and operation of repression. Accordingly, this paper revisits the master signifier concept, and does so within the socio-political domain, yet while paying particular attention to the functioning of unconscious processes of fantasy and repression. More specifically, it investigates how Nelson Mandela operates as a master signifier in contemporary South Africa, as a vital means of knitting together diverse elements of post-apartheid society, enabling the fantasy of the post-apartheid nation, and holding at bay a whole series of repressed and negated undercurrents.

  15. Revisiting the OH-CH correlation in diffuse clouds

    CERN Document Server

    Mookerjea, Bhaswati

    2016-01-01

    Based on the analysis of available published data and archival data along 24 sightlines (5 of which are new) we derive more accurate estimates of the column densities of OH and CH towards diffuse/translucent clouds and revisit the typically observed correlation between the abundances of these species. The increase in the sample size was possible because of the equivalence of the column densities of CH derived from a combination of the transitions at 3137 & 3143 Angstrom, and a combination of transitions at 3886 & 3890 Angstrom, which we have demonstrated here. We find that with the exception of four diffuse clouds, the entire source sample shows a clear correlation between the column densities of OH and CH similar to previous observations. The analysis presented also verifies the theoretically predicted oscillator strengths of the OH A--X (3078 & 3082 Angstrom), CH B--X (3886 & 3890 Angstrom) and C--X (3137 & 3143 Angstrom) transitions. We estimate N(H) and N(H2) from the observed E(B-V) a...

  16. The angular momentum of baryons and dark matter halos revisited

    CERN Document Server

    Kimm, Taysun; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive mesh refinement, we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r=0.1rvir. In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/rvir>0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its ...

  17. The interaction of atoms with LiF(001) revisited

    CERN Document Server

    Miraglia, J E

    2016-01-01

    Pairwise additive potentials for multielectronic atoms interacting with a LiF(001) surface are revisited by including an improved description of the electron density associated with the different lattice sites, as well as non-local electron density contributions. Within this model, the electron distribution around each ionic site of the crystal is described by means of an onion approach that accounts for the influence of the Madelung potential. From such densities, binary interatomic potentials are then derived by using well-known non-local functionals for the kinetic, exchange and correlation terms. Rumpling and long-range contributions due to projectile polarization and van der Waals forces are also included in an analogous fashion. We apply this pairwise additive approximation to evaluate the interaction potential between closed-shell - He, Ne, Ar, Kr, and Xe - and open-shell - N, S, and Cl - atoms and the LiF surface, analyzing the relative importance of the different contributions. The performance of the...

  18. Biogas from Macroalgae: is it time to revisit the idea?

    Directory of Open Access Journals (Sweden)

    Hughes Adam D

    2012-11-01

    Full Text Available Abstract The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example.

  19. The Mantel-Haenszel procedure revisited: models and generalizations.

    Directory of Open Access Journals (Sweden)

    Vaclav Fidler

    Full Text Available Several statistical methods have been developed for adjusting the Odds Ratio of the relation between two dichotomous variables X and Y for some confounders Z. With the exception of the Mantel-Haenszel method, commonly used methods, notably binary logistic regression, are not symmetrical in X and Y. The classical Mantel-Haenszel method however only works for confounders with a limited number of discrete strata, which limits its utility, and appears to have no basis in statistical models. Here we revisit the Mantel-Haenszel method and propose an extension to continuous and vector valued Z. The idea is to replace the observed cell entries in strata of the Mantel-Haenszel procedure by subject specific classification probabilities for the four possible values of (X,Y predicted by a suitable statistical model. For situations where X and Y can be treated symmetrically we propose and explore the multinomial logistic model. Under the homogeneity hypothesis, which states that the odds ratio does not depend on Z, the logarithm of the odds ratio estimator can be expressed as a simple linear combination of three parameters of this model. Methods for testing the homogeneity hypothesis are proposed. The relationship between this method and binary logistic regression is explored. A numerical example using survey data is presented.

  20. The Mantel-Haenszel procedure revisited: models and generalizations.

    Science.gov (United States)

    Fidler, Vaclav; Nagelkerke, Nico

    2013-01-01

    Several statistical methods have been developed for adjusting the Odds Ratio of the relation between two dichotomous variables X and Y for some confounders Z. With the exception of the Mantel-Haenszel method, commonly used methods, notably binary logistic regression, are not symmetrical in X and Y. The classical Mantel-Haenszel method however only works for confounders with a limited number of discrete strata, which limits its utility, and appears to have no basis in statistical models. Here we revisit the Mantel-Haenszel method and propose an extension to continuous and vector valued Z. The idea is to replace the observed cell entries in strata of the Mantel-Haenszel procedure by subject specific classification probabilities for the four possible values of (X,Y) predicted by a suitable statistical model. For situations where X and Y can be treated symmetrically we propose and explore the multinomial logistic model. Under the homogeneity hypothesis, which states that the odds ratio does not depend on Z, the logarithm of the odds ratio estimator can be expressed as a simple linear combination of three parameters of this model. Methods for testing the homogeneity hypothesis are proposed. The relationship between this method and binary logistic regression is explored. A numerical example using survey data is presented. PMID:23516463

  1. Psychological Well-Being Revisited: Advances in Science and Practice

    Science.gov (United States)

    Ryff, Carol D.

    2014-01-01

    This article reviews the research and interventions that have grown up around a model of psychological well-being (Ryff, 1989) generated more than two decades ago to address neglected aspects of positive functioning, such as purposeful engagement in life, realization of personal talents and capacities, and enlightened self-knowledge. The conceptual origins of this formulation are revisited and scientific products emerging from six thematic areas are examined: (1) how well-being changes across adult development and later life, (2) what are the personality correlates of well-being, (3) how well-being is linked with experiences in family life, (4) how well-being relates to work and other community activities, (5) what are the connections between well-being and health, including biological risk factors, (6) and via clinical and intervention studies, how psychological well-being can be promoted for ever greater segments of society. Together, these topics illustrate flourishing interest across diverse scientific disciplines in understanding adults as striving, meaning-making, proactive organisms who are actively negotiating the challenges of life. A take-home message is that increasing evidence supports the health protective features of psychological well-being in reducing risk for disease and promoting length of life. A recurrent and increasingly important theme is resilience – the capacity to maintain or regain well-being in the face of adversity. Implications for future research and practice are considered. PMID:24281296

  2. Revisiting the Master-Signifier, or, Mandela and Repression

    Science.gov (United States)

    Hook, Derek; Vanheule, Stijn

    2016-01-01

    The concept of the master-signifier has been subject to a variety of applications in Lacanian forms of political discourse theory and ideology critique. While there is much to be commended in literature of this sort, it often neglects salient issues pertaining to the role of master signifiers in the clinical domain of (individual) psychical economy. The popularity of the concept of the master (or “empty”) signifier in political discourse analysis has thus proved a double-edged sword. On the one hand it demonstrates how crucial psychical processes are performed via the operations of the signifier, extending thus the Lacanian thesis that identification is the outcome of linguistic and symbolic as opposed to merely psychological processes. On the other, the use of the master signifier concept within the political realm to track discursive formations tends to distance the term from the dynamics of the unconscious and operation of repression. Accordingly, this paper revisits the master signifier concept, and does so within the socio-political domain, yet while paying particular attention to the functioning of unconscious processes of fantasy and repression. More specifically, it investigates how Nelson Mandela operates as a master signifier in contemporary South Africa, as a vital means of knitting together diverse elements of post-apartheid society, enabling the fantasy of the post-apartheid nation, and holding at bay a whole series of repressed and negated undercurrents. PMID:26834664

  3. Fever tree revisited: From malaria to autoinflammatory diseases.

    Science.gov (United States)

    Pastore, Serena; Vuch, Josef; Bianco, Anna Monica; Taddio, Andrea; Tommasini, Alberto

    2015-11-01

    Over the centuries the idea of recurrent fevers has mainly been associated with malaria, but many other fevers, such as typhoid and diphtheria were cause for concern. It is only in recent times, with the more severe forms of fever from infectious origin becoming less frequent or a cause for worry that we started noticing recurrent fevers without any clear infectious cause, being described as having a pathogenesis of autoinflammatory nature. The use of molecular examinations in many cases can allow a diagnosis where the cause is monogenic. In other cases, however the pathogenesis is likely to be multifactorial and the diagnostic-therapeutic approach is strictly clinical. The old fever tree paradigm developed to describe fevers caused by malaria has been revisited here to describe today's periodic fevers from the periodic fever adenitis pharyngitis aphthae syndrome to the more rare autoinflammatory diseases. This model may allow us to place cases that are yet to be identified which are likely to be of multifactorial origin. PMID:26566482

  4. Revisiting the quantum Szilard engine with fully quantum considerations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hai [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); School of Information and Electronics Engineering, Shandong Institute of Business and Technology, Yantai 264000 (China); Zou, Jian, E-mail: zoujian@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Li, Jun-Gang; Shao, Bin [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Wu, Lian-Ao [Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), P.O. Box 644, ES-48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, ES-48011 Bilbao (Spain)

    2012-12-15

    By considering level shifting during the insertion process we revisit the quantum Szilard engine (QSZE) with fully quantum consideration. We derive the general expressions of the heat absorbed from thermal bath and the total work done to the environment by the system in a cycle with two different cyclic strategies. We find that only the quantum information contributes to the absorbed heat, and the classical information acts like a feedback controller and has no direct effect on the absorbed heat. This is the first demonstration of the different effects of quantum information and classical information for extracting heat from the bath in the QSZE. Moreover, when the well width L{yields}{infinity} or the temperature of the bath T{yields}{infinity} the QSZE reduces to the classical Szilard engine (CSZE), and the total work satisfies the relation W{sub tot}=k{sub B}Tln2 as obtained by Sang Wook Kim et al. [S.W. Kim, T. Sagawa, S. De Liberato, M. Ueda, Phys. Rev. Lett. 106 (2011) 070401] for one particle case. - Highlights: Black-Right-Pointing-Pointer For the first time analyze the QSZE by considering energy level shifts. Black-Right-Pointing-Pointer Find different roles played by classical and quantum information in the QSZE. Black-Right-Pointing-Pointer The amount of work extracted depends on the cyclic strategies of the QSZE. Black-Right-Pointing-Pointer Verify that the QSZE will reduce to the CSZE in the classical limits.

  5. SUSY effects in Rb: Revisited under current experimental constraints

    Science.gov (United States)

    Su, Wei; Yang, Jin Min

    2016-06-01

    In this note we revisit the SUSY effects in Rb under current experimental constraints including the LHC Higgs data, the B-physics measurements, the dark matter relic density and direct detection limits, as well as the precision electroweak data. We first perform a scan to figure out the currently allowed parameter space and then display the SUSY effects in Rb. We find that although the SUSY parameter space has been severely restrained by current experimental data, both the general MSSM and the natural-SUSY scenario can still alter Rb with a magnitude sizable enough to be observed at future Z-factories (ILC, CEPC, FCC-ee, Super Z-factory) which produce 109-1012Z-bosons. To be specific, assuming a precise measurement δRb = 2.0 ×10-5 at FCC-ee, we can probe a right-handed stop up to 530 GeV through chargino-stop loops, probe a sbottom to 850 GeV through neutralino-sbottom loops and a charged Higgs to 770 GeV through the Higgs-top quark loops for a large tan ⁡ β. The full one-loop SUSY correction to Rb can reach 1 ×10-4 in natural SUSY and 2 ×10-4 in the general MSSM.

  6. Leber′s hereditary optic neuropathy: The mitochondrial connection revisited

    Directory of Open Access Journals (Sweden)

    Khaled K Abu-Amero

    2011-01-01

    Full Text Available Our current understanding of Leber′s hereditary optic neuropathy (LHON-mitochondrial connection falls short of comprehensive. Twenty years of intensive investigation have yielded a wealth of information about mitochondria, the mitochondrial genome, the metabolism of the optic nerve and other structures, and the phenotypic variability of classic LHON. However, we still cannot completely explain how primary LHON mutations injure the optic nerve or why the optic nerve is particularly at risk. We cannot explain the incomplete penetrance or the male predominance of LHON, the typical onset in young adult life without warning, or the synchronicity of visual loss. Moreover, primary LHON mutations clearly are not present in every family with the LHON phenotype (including multigenerational maternal inheritance, and they are present in only a minority of individuals who have the LHON optic neuropathy phenotype without a family history. All lines of evidence point to abnormalities of the mitochondria as the direct or indirect cause of LHON. Therefore, the mitochondria-LHON connection needs to be revisited and examined closely. This review will attempt to do that and provide an update on various aspects of LHON.

  7. An Adaptive and Hybrid Approach for Revisiting the Visibility Pipeline

    Directory of Open Access Journals (Sweden)

    Ícaro Lins Leitão da Cunha

    2016-04-01

    Full Text Available We revisit the visibility problem, which is traditionally known in Computer Graphics and Vision fields as the process of computing a (potentially visible set of primitives in the computational model of a scene. We propose a hybrid solution that uses a dry structure (in the sense of data reduction, a triangulation of the type J1a, to accelerate the task of searching for visible primitives. We came up with a solution that is useful for real-time, on-line, interactive applications as 3D visualization. In such applications the main goal is to load the minimum amount of primitives from the scene during the rendering stage, as possible. For this purpose, our algorithm executes the culling by using a hybrid paradigm based on viewing-frustum, back-face culling and occlusion models. Results have shown substantial improvement over these traditional approaches if applied separately. This novel approach can be used in devices with no dedicated processors or with low processing power, as cell phones or embedded displays, or to visualize data through the Internet, as in virtual museums applications.

  8. Revisiting the Source Process of the 2007 Tocopilla, Chile Earthquake

    Science.gov (United States)

    Simons, M.; Minson, S. E.; Jolivet, R.; Jiang, J.; Beck, J. L.

    2013-12-01

    We revisit the 2007 Mw 7.7 Tocopilla, Chile earthquake to create a finite fault kinematic source model based on the current best practices in data analysis and inversion methods. The data used to constrain the source model include both static GPS offsets and 1 Hz kinematic GPS time series, as well as interferograms which have been reanalyzed to remove tropospheric effects which can be quite significant in this region. Our inversion methodology is a Bayesian approach that uses only physics-based constraints on the rupture evolution, and which utilizes models of both the observational noise and the errors in our forward model to obtain the ensemble of all plausible rupture models which satisfy both the data and our a priori assumptions. This approach allows us to better understand which parts of the rupture process are well-constrained and which are not, and thus to better understand how the 2007 Tocopilla, Chile earthquake rupture fits into the sequence of large earthquakes which have been mosaicking the northern Chile subduction zone.

  9. Leptogenesis in the two right-handed neutrino model revisited

    CERN Document Server

    Antusch, S; Jones, D A; King, S F

    2011-01-01

    We revisit leptogenesis in the minimal non-supersymmetric type I see-saw mechanism with two right-handed (RH) neutrinos, including flavour effects and allowing both RH neutrinos N_1 and N_2 to contribute, rather than just the lightest RH neutrino N_1 that has hitherto been considered. By performing scans over parameter space in terms of the single complex angle z of the orthogonal matrix R, for a range of PMNS parameters, we find that in regions around z \\sim \\pm \\pi/2, for the case of a normal mass hierarchy, the N_2 contribution can dominate the contribution to leptogenesis, allowing the lightest RH neutrino mass to be decreased by about an order of magnitude in these regions, down to M_1 \\sim 7*10^10 GeV for initial thermal N_2-abundance, with the numerical results supported by analytic estimates. We show that the regions around z \\sim \\pm \\pi /2 correspond to light sequential dominance, so the new results in this paper may be relevant to unified model building.

  10. Revisiting reflexology: Concept, evidence, current practice, and practitioner training.

    Science.gov (United States)

    Embong, Nurul Haswani; Soh, Yee Chang; Ming, Long Chiau; Wong, Tin Wui

    2015-10-01

    Reflexology is basically a study of how one part of the human body relates to another part of the body. Reflexology practitioners rely on the reflexes map of the feet and hands to all the internal organs and other human body parts. They believe that by applying the appropriate pressure and massage certain spots on the feet and hands, all other body parts could be energized and rejuvenated. This review aimed to revisit the concept of reflexology and examine its effectiveness, practices, and the training for reflexology practitioners. PubMed, SCOPUS, Google Scholar, and SpringerLink databases were utilized to search the following medical subject headings or keywords: foot massage, reflexology, foot reflexotherapy, reflexological treatment, and zone therapy. The articles published for the last 10 years were included. Previous systematic reviews failed to show concrete evidence for any specific effect of reflexology in any conditions. Due to its non-invasive, non-pharmacological complementary nature, reflexology is widely accepted and anecdotal evidence of positive effect reflexology in a variety of health conditions are available. Adequate training for practitioners is necessary to ensure the consistency of service provided. PMID:26587391

  11. ISLAM, ADAT, AND THE STATE: Matrifocality in Aceh Revisited

    Directory of Open Access Journals (Sweden)

    Eka Srimulyani

    2010-08-01

    Full Text Available Matrifocality has been a rooted tradition in the social history of the community in Aceh. The principles of matrifocality have also affected on how women are positioned in the community, and the socio-gender relation within the community. The fact that Aceh has strongly associated to the Islamic values that claimed to support the paternal traditions. Apparently, the Islamic values and the local matrifocality practices juxtaposed through the roles of adat, which considered as inseparable to Islamic law or teaching, or in local term known as zat ngeun sifeut. Another point in revisiting matrifocality in Aceh in Aceh is an examination of how gender state ideology, particularly during the New Order Regime disregarded some local gender practices across some ethnics in the archipelago. Meanwhile, the state also hegemonied and promoted particular gender state ideology such as state ibuism. Nonetheless, the modernity and social changes have also contributed to the shifting of some matrifocality practices in contemporary Acehnese society. However, since the matrifocality has a strong root in the social life of the community, the principles of the matrifocality still survived until currently, although it transformed into ‘new matrifocality’ practices. Keywords: matrifocality, Aceh, gender, shari‘a law

  12. Automated Guidance for Thermodynamics Essays: Critiquing Versus Revisiting

    Science.gov (United States)

    Donnelly, Dermot F.; Vitale, Jonathan M.; Linn, Marcia C.

    2015-12-01

    Middle school students struggle to explain thermodynamics concepts. In this study, to help students succeed, we use a natural language processing program to analyze their essays explaining the aspects of thermodynamics and provide guidance based on the automated score. The 346 sixth-grade students were assigned to either the critique condition where they criticized an explanation or the revisit condition where they reviewed visualizations. Within each condition, the student was assigned one of two types of tailored guidance based on the sophistication of their original essay. Both forms of guidance led to significant improvement in student understanding on the posttest. Guidance was more effective for students with low prior knowledge than for those with high prior knowledge (consistent with regression toward the mean). However, analysis of student responses to the guidance illustrates the value of aligning guidance with prior knowledge. All students were required to revise their essay as an embedded assessment. While effective, teachers involved in this study reported that revising is resisted by students and does not align with typical, vocabulary-focused classroom writing activities.

  13. Revisiting Cosmic No-Hair Theorem for Inflationary Settings

    CERN Document Server

    Maleknejad, A

    2012-01-01

    In this work we revisit Wald's cosmic no-hair theorem in the context of accelerating Bianchi cosmologies for a generic cosmic fluid with non-vanishing anisotropic stress tensor and when the fluid energy momentum tensor is of the form of a cosmological constant term plus a piece which does not respect strong or dominant energy conditions. Such a fluid is the one appearing in inflationary models. We show that for such a system anisotropy may grow, in contrast to the cosmic no-hair conjecture. In particular, for a generic inflationary model we show that there is an upper bound on the growth of anisotropy. For slow-roll inflationary models our analysis can be refined further and the upper bound is found to be of the order of slow-roll parameters. We examine our general discussions and our extension of Wald's theorem for three classes of slow-roll inflationary models, generic multi-scalar field driven models, anisotropic models involving U(1) gauge fields and the gauge-flation scenario.

  14. Finite size effect on classical ideal gas revisited

    Science.gov (United States)

    Ghosh, P.; Ghosh, S.; Mitra, J.; Bera, N.

    2015-09-01

    Finite size effects on classical ideal gas are revisited. The micro-canonical partition function for a collection of ideal particles confined in a box is evaluated using Euler-Maclaurin’s as well as Poisson's summation formula. In Poisson's summation formula there are some exponential terms which are absent in Euler-Maclaurin’s formula. In the thermodynamic limit the exponential correction is negligibly small but in the macro/nano dimensions and at low temperatures they may have a great significance. The consequences of finite size effects have been illustrated by redoing the calculations in one and three dimensions keeping the exponential corrections. Global and local thermodynamic properties, diffusion driven by the finite size effect, and effect on speed of sound have been discussed. Thermo-size effects, similar to thermoelectric effects, have been described in detail and may be a theoretical basis with which to design nano-scaled devices. This paper can also be very helpful for undergraduate and graduate students in physics and chemistry as an instructive exercise for a good course in statistical mechanics.

  15. Radiation accidents

    International Nuclear Information System (INIS)

    Radiation accidents may be viewed as unusual exposure event which provide possible high exposure to a few people and, in the case of nuclear plants events, low exposure to large population. A number of radiation accidents have occurred over the past 50 years, involving radiation machines, radioactive materials and uncontrolled nuclear reactors. These accidents have resulted in number of people have been exposed to a range of internal and external radiation doses and those involving radioactive materials have involved multiple routs of exposure. Some of the more important accidents involving significant radiation doses or releases of radioactive materials, including any known health effects involves in it. An analysis of the common characteristics of accidents is useful resolving overarching issues, as has been done following nuclear power, industrial radiography and medical accidents. Success in avoiding accidents and responding when they do occur requires planning in order to have adequately trained and prepared health physics organization; well defined and developed instrument program; close cooperation among radiation protection experts, local and state authorities. Focus is given to the successful avoidance of accidents and response in the events they do occur. Palomares, spain in late 1960, Goiania, Brazil in 1987, Thule, Greenland in 1968, Rocky flats, Colorado in 1957 and 1969, Three mile island, Pennsylvania in 1979, Chernobyl Ukraine in april 1986, Kyshtym, former Soviet Union in 1957, Windscale, UK in Oct. 1957 Tomsk, Russian Federation in 1993, and many others are the important examples of major radiation accidents. (author)

  16. FROM THE BLAZAR SEQUENCE TO THE BLAZAR ENVELOPE: REVISITING THE RELATIVISTIC JET DICHOTOMY IN RADIO-LOUD ACTIVE GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    We revisit the concept of a blazar sequence that relates the synchrotron peak frequency (νpeak) in blazars with synchrotron peak luminosity (Lpeak, in νLν) using a large sample of radio-loud active galactic nuclei. We present observational evidence that the blazar sequence is formed from two populations in the synchrotron νpeak-Lpeak plane, each forming an upper edge to an envelope of progressively misaligned blazars, and connecting to an adjacent group of radio galaxies having jets viewed at much larger angles to the line of sight. When binned by jet kinetic power (Lkin; as measured through a scaling relationship with extended radio power), we find that radio core dominance decreases with decreasing synchrotron Lpeak, revealing that sources in the envelope are generally more misaligned. We find population-based evidence of velocity gradients in jets at low kinetic powers (∼1042-1044.5 erg s-1), corresponding to Fanaroff-Riley (FR) I radio galaxies and most BL Lac objects. These low jet power 'weak-jet' sources, thought to exhibit radiatively inefficient accretion, are distinguished from the population of non-decelerating, low synchrotron-peaking (LSP) blazars and FR II radio galaxies ('strong' jets) which are thought to exhibit radiatively efficient accretion. The two-population interpretation explains the apparent contradiction of the existence of highly core-dominated, low-power blazars at both low and high synchrotron peak frequencies, and further implies that most intermediate synchrotron peak sources are not intermediate in intrinsic jet power between LSP and high synchrotron-peaking (HSP) sources, but are more misaligned versions of HSP sources with similar jet powers.

  17. From the Blazar Sequence to the Blazar Envelope: Revisiting the Relativistic Jet Dichotomy in Radio-Loud AGN

    Science.gov (United States)

    Meyer, Eileen T.; Fossati, Giovanini; Georganopoulos, Markos; Lister, Matthew L.

    2012-01-01

    We revisit the concept of a blazar sequence that relates the synchrotron peak frequency (Vpeak) in blazars with synchrotron peak luminosity (Lpeak, in vLv) using a large sample of radio-loud AGN. We present observational evidence that the blazar sequence is formed from two populations in the synchrotron Vpeak - Lpeak plane, each forming an upper edge to an envelope of progressively misaligned blazars, and connecting to an adjacent group of radio galaxies having jets viewed at much larger angles to the line of sight. When binned by jet kinetic power (Lkin; as measured through a scaling relationship with extended radio power), we find that radio core dominance decreases with decreasing synchrotron Lpeak, revealing that sources in the envelope are generally more misaligned. We find population-based evidence of velocity gradients in jets at low kinetic powers (approximately 10(exp 42) - 10(exp 44.5) erg s(exp -1)), corresponding to FR I radio galaxies and most BL Lacs. These low jet power 'weak jet' sources, thought to exhibit radiatively inefficient accretion, are distinguished from the population of non-decelerating, low synchrotron-peaking (LSP) blazars and FR II radio galaxies ('strong' jets) which are thought to exhibit radiatively efficient accretion. The two-population interpretation explains the apparent contradiction of the existence of highly core-dominated, low-power blazars at both low and high synchrotron peak frequencies, and further implies that most intermediate synchrotron peak (ISP) sources are not intermediate in intrinsic jet power between LSP and high synchrotron-peaking (HSP) sources, but are more misaligned versions of HSP sources with similar jet powers.

  18. Radiation Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Castor, J I

    2003-10-16

    The discipline of radiation hydrodynamics is the branch of hydrodynamics in which the moving fluid absorbs and emits electromagnetic radiation, and in so doing modifies its dynamical behavior. That is, the net gain or loss of energy by parcels of the fluid material through absorption or emission of radiation are sufficient to change the pressure of the material, and therefore change its motion; alternatively, the net momentum exchange between radiation and matter may alter the motion of the matter directly. Ignoring the radiation contributions to energy and momentum will give a wrong prediction of the hydrodynamic motion when the correct description is radiation hydrodynamics. Of course, there are circumstances when a large quantity of radiation is present, yet can be ignored without causing the model to be in error. This happens when radiation from an exterior source streams through the problem, but the latter is so transparent that the energy and momentum coupling is negligible. Everything we say about radiation hydrodynamics applies equally well to neutrinos and photons (apart from the Einstein relations, specific to bosons), but in almost every area of astrophysics neutrino hydrodynamics is ignored, simply because the systems are exceedingly transparent to neutrinos, even though the energy flux in neutrinos may be substantial. Another place where we can do ''radiation hydrodynamics'' without using any sophisticated theory is deep within stars or other bodies, where the material is so opaque to the radiation that the mean free path of photons is entirely negligible compared with the size of the system, the distance over which any fluid quantity varies, and so on. In this case we can suppose that the radiation is in equilibrium with the matter locally, and its energy, pressure and momentum can be lumped in with those of the rest of the fluid. That is, it is no more necessary to distinguish photons from atoms, nuclei and electrons, than it is

  19. The Best and the Rest: Revisiting the Norm of Normality of Individual Performance

    Science.gov (United States)

    O'Boyle, Ernest, Jr.; Aguinis, Herman

    2012-01-01

    We revisit a long-held assumption in human resource management, organizational behavior, and industrial and organizational psychology that individual performance follows a Gaussian (normal) distribution. We conducted 5 studies involving 198 samples including 633,263 researchers, entertainers, politicians, and amateur and professional athletes.…

  20. Revisiting the Gun Ownership and Violence Link; a multi- level analysis of victimisation survey data.

    NARCIS (Netherlands)

    van Kesteren, J.N.

    2014-01-01

    The link between gun ownership victimisation by violent crime remains one of the most contested issues in criminology. Some authors claim that high gun availability facilitates serious violence. Others claim that gun ownership prevents crime. This article revisits these issues using individual and a

  1. Revisiting Individual Creativity Assessment: Triangulation in Subjective and Objective Assessment Methods

    Science.gov (United States)

    Park, Namgyoo K.; Chun, Monica Youngshin; Lee, Jinju

    2016-01-01

    Compared to the significant development of creativity studies, individual creativity research has not reached a meaningful consensus regarding the most valid and reliable method for assessing individual creativity. This study revisited 2 of the most popular methods for assessing individual creativity: subjective and objective methods. This study…

  2. The skeptical green consumer revisited: testing the relationship between green consumerism and skepticism toward advertising

    NARCIS (Netherlands)

    J. Matthes; A. Wonneberger

    2014-01-01

    This article revisits the widely believed notion of the skeptical green consumer, in other words, that green consumers tend to distrust green advertising. Study 1, a survey of U.S. consumers, found no positive relationship between green consumerism and general ad skepticism. However, green consumeri

  3. Framing the Future: Revisiting the Place of Educational Expectations in Status Attainment

    Science.gov (United States)

    Bozick, Robert; Alexander, Karl; Entwisle, Doris; Dauber, Susan; Kerr, Kerri

    2010-01-01

    This study revisits the Wisconsin model of status attainment from a life course developmental perspective. Fixed-effects regression analyses lend strong support to the Wisconsin framework's core proposition that academic performance and significant others' influence shape educational expectations. However, investigating the process of expectation…

  4. Revisiting "Grutter" and "Gratz" in the Wake of "Fisher": Looking Back to Move Forward

    Science.gov (United States)

    Ledesma, Maria C.

    2013-01-01

    This article revisits the University of Michigan's 2003 affirmative action cases, "Grutter v. Bollinger" and "Gratz v. Bollinger." Through the aid of critical textual analysis and critical race theory, the author looks back at the predominant narratives that framed the challenge to, and defense of, race-conscious affirmative action policy in the…

  5. Revisiting Interpretation of Canonical Correlation Analysis: A Tutorial and Demonstration of Canonical Commonality Analysis

    Science.gov (United States)

    Nimon, Kim; Henson, Robin K.; Gates, Michael S.

    2010-01-01

    In the face of multicollinearity, researchers face challenges interpreting canonical correlation analysis (CCA) results. Although standardized function and structure coefficients provide insight into the canonical variates produced, they fall short when researchers want to fully report canonical effects. This article revisits the interpretation of…

  6. Instant Video Revisiting for Reflection: Extending the Learning of Children and Teachers.

    Science.gov (United States)

    Hong, Seong B.; Broderick, Jane T.

    This article discusses how instant video revisiting (IVR) promotes reflective thinking for both teachers and children. IVR was used as a daily classroom experience with both the children and the teachers throughout one semester in two preschool classrooms with children 2.5 to 5 years old. The teachers used a digital video camera to generate data…

  7. Revisiting First-Year College Students' Mattering: Social Support, Academic Stress, and the Mattering Experience

    Science.gov (United States)

    Rayle, Andrea Dixon; Chung, Kuo-Yi

    2008-01-01

    In this study, Nancy Schlossberg's (1989) theory of college students' mattering to others was revisited. Mattering is the experience of others depending on us, being interested in us, and being concerned with our fate. The relationships of gender, mattering to college friends and the college environment, and friend and family social support with…

  8. The Influence of Service Quality and Food Quality Towards Customer Fulfillment and Revisit Intention

    Directory of Open Access Journals (Sweden)

    Siti Nor Fadillah Binti Ahmad Shariff

    2015-08-01

    Full Text Available The intensely competitive environment existing in the restaurant sector makes it vital for firms to achieve customer satisfaction in order to survive in the long term. Obtaining customer satisfaction means that they become an effective and efficient communication resource, at no cost to the firm. Prominent among the factors that determine the levels of customer satisfaction in the food and beverage contexts are service quality and product quality. Nowadays, Chinese cuisine is becoming more attractive and accepted worldwide. Due to large population of Chinese Muslims in Malaysia, restaurants catered or owned by Chinese Muslims are now increasing and cater to all races in Malaysia. Therefore, the objective of the study is to identify the relationship between service quality and product quality towards customer satisfaction and examine revisit intentions of 9 Chinese Muslim restaurants in Shah Alam, Malaysia. The questionnaire was tested for reliability before being used. Correlation and regression analysis were employed to investigate the relationship between the service and product (food, customer satisfaction and revisit intentions to these restaurants. The findings of this study indicate that service quality and food quality have a significant relationship on customer satisfaction and thus have a significant relationship towards revisit intention. In conclusion, it was found that all customers were satisfied with these restaurants and willing to recommend Chinese Muslim restaurants to their relatives and friends and they were also willing to revisit this type of restaurant in the future.

  9. Re-Visit to the School Nurse and Adolescents' Medicine Use

    Science.gov (United States)

    Borup, Ina K.; Andersen, Anette; Holstein, Bjorn E.

    2011-01-01

    Objective: To examine if students who re-visit the school nurse use medicines differently than other students when exposed to aches and psychological problems. Methods: The study includes all 11-, 13- and 15-year-old students from a random sample of schools in Denmark, response rate 87 per cent, n = 5,205. The data collection followed the…

  10. The Concept of Experience by John Dewey Revisited: Conceiving, Feeling and "Enliving"

    Science.gov (United States)

    Hohr, Hansjorg

    2013-01-01

    "The concept of experience by John Dewey revisited: conceiving, feeling and 'enliving'." Dewey takes a few steps towards a differentiation of the concept of experience, such as the distinction between primary and secondary experience, or between ordinary (partial, raw, primitive) experience and complete, aesthetic experience. However, he does not…

  11. Revisiting Feminism and Australian Education: Who Speaks? What Questions? What Contexts? What Impact?

    Science.gov (United States)

    Yates, Lyn

    2008-01-01

    This article revisits the development of feminist research and policy in education in Australia in the mid-1970s to mid-1980s from the perspective of the present decade. The purpose is to give one insider's account of the specificities of that initial period, and to use that analysis to draw attention to changes evident in the context and agendas…

  12. Asian Lifelong Learning in the Context of a Global Knowledge Economy: A Task Re-Visited

    Science.gov (United States)

    Han, Soonghee

    2007-01-01

    This article revisits and reinterprets my previous paper. It is a snapshot of the lifelong learning system building in selected Asian countries, reflected in the mirror of the Asian Financial Crisis in the 1997s and the aftermath of that event. I reconsidered the arguments (1) the economic recession had delivered a global dimension of lifelong…

  13. Experiments on the Divergence between Willingness to Pay and Willingness to Accept: The Issue Revisited

    OpenAIRE

    Rodolfo M. Nayga, Jr.; Wipon Aiew; Richard Woodward

    2005-01-01

    Many empirical studies have discovered large discrepancies between willingness to pay (WTP) and willingness to accept (WTA) measures. This paper revisits the WTP and WTA divergence issue using a non-hypothetical market experiment, actual products, cash, and exchange in a market setting. We find WTA/WTP ratios that are significantly lower than most such studies.

  14. Service-Learning in Crisis Communication Education: Revisiting Coombs' Objectives for the Crisis Communication Course

    Science.gov (United States)

    Maresh-Fuehrer, Michelle M.

    2015-01-01

    The purpose of this study was to revisit Coombs' suggestions for teaching the crisis communication course using service-learning as a framework. The author sought to assess the effectiveness of using this method in terms of the benefits to both students and the partnering organization and students' perceptions of whether they met the learning…

  15. Formative Assessment: Revisiting the Territory from the Point of View of Teachers

    Science.gov (United States)

    Morrissette, Joelle

    2011-01-01

    This research documented the know-how of five elementary-school teachers regarding formative assessment, working from their point of view on the question. Group interviews gave them the opportunity to negotiate their "ways of doing things," by revisiting and elaborating upon assessment episodes that had been previously identified on classroom…

  16. Revisiting the extended spring indices using gridded weather data and machine learning

    Science.gov (United States)

    Mehdipoor, Hamed; Izquierdo-Verdiguier, Emma; Zurita-Milla, Raul

    2016-04-01

    The extended spring indices or SI-x [1] have been successfully used to predict the timing of spring onset at continental scales. The SI-x models were created by combining lilac and honeysuckle volunteered phenological observations, temperature data (from weather stations) and latitudinal information. More precisely, these models use a linear regression to predict the day of year of first leaf and first bloom for these two indicator species. In this contribution we revisit both the data and the method used to calibrate the SI-x models to check whether the addition of new input data or the use of non-linear regression methods could lead to improments in the model outputs. In particular, we use a recently published dataset [2] of volunteered observations on cloned and common lilac over longer period of time (1980-2014) and we replace the weather station data by 54 features derived from Daymet [3], which provides 1 by 1 km gridded estimates of daily weather parameters (maximum and minimum temperatures, precipitation, water vapor pressure, solar radiation, day length, snow water equivalent) for North America. These features consist of both daily weather values and their long- and short-term accumulations and elevation. we also replace the original linear regression by a non-linear method. Specifically, we use random forests to both identify the most important features and to predict the day of year of the first leaf of cloned and common lilacs. Preliminary results confirm the importance of the SI-x features (maximum and minimum temperatures and day length). However, our results show that snow water equivalent and water vapor pressure are also necessary to properly model leaf onset. Regarding the predictions, our results indicate that Random Forests yield comparable results to those produced by the SI-x models (in terms of root mean square error -RMSE). For cloned and common lilac, the models predict the day of year of leafing with 16 and 15 days of accuracy respectively

  17. Radiation Therapy

    Science.gov (United States)

    ... therapy. At this time, you will have a physical exam , talk about your medical history , and maybe have imaging tests . Your doctor or nurse will discuss external beam radiation therapy, its benefits and side effects, and ways you can care ...

  18. Synchrotron radiation

    International Nuclear Information System (INIS)

    A detailed account of the research work associated with the Synchrotron Radiation Source at Daresbury Laboratory, United Kingdom, in 1984/85, is presented in the Appendix to the Laboratory's Annual Report. (U.K.)

  19. Radiation sensors

    International Nuclear Information System (INIS)

    Radiation detectors, suitable for use in industrial environments, eg coal mines are claimed. At least two scintillation crystals are mounted on a resilient support material, preferably silicone rubber. The sensors are both robust and compact. (U.K.)

  20. Radiation curing

    International Nuclear Information System (INIS)

    In the beginning of the seventies the two types of radiation sources applied in industrial processes, electron radiation and UV, had been given rather optimistic forecasts. While UV could succeed in the field of panel and film coating, electron radiation curing seems to gain success in quite new fields of manufacturing. The listing of the suggested applications of radiation curing and a comparison of both advantages and disadvantages of this technology are followed by a number of case studies emphasizing the features of these processes and giving some examplary calculations. The data used for the calculations should provide an easy calculation of individual manufacturing costs if special production parameters, investment or energy costs are employed. (Author)

  1. Radiation sterilisation

    International Nuclear Information System (INIS)

    The South African Atomic Energy Board operates an irradiation plant for the sterilisation of pharmaceutical products at Pelindaba. The advantages of this plant are discussed as well as the position radiation processing currently enjoys in industry

  2. Electromagnetic Radiation

    OpenAIRE

    Andrews, D L

    2010-01-01

    Electromagnetic radiation, commonly referred to as light, underpins all spectroscopic techniques, ranging from the highly energetic gamma rays, through x-rays, ultraviolet, visible, infrared, microwaves to the low-energy radio waves. The principles of wave- and particle-like behaviour determine the nature of the radiation and its interaction with matter, whether in the form of subatomic, atomic, molecular or macromolecular structures. © 1999 Elsevier Ltd All rights reserved.

  3. Synchrotron radiation

    International Nuclear Information System (INIS)

    A report is given on the work involving the Synchrotron Radiation Division of the Daresbury Laboratory during the period January 1981 - March 1982. Development of the source, beamlines and experimental stations is described. Progress reports from individual investigators are presented which reveal the general diversity and interdisciplinary nature of the research which benefits from access to synchrotron radiation and the associated facilities. Information is given on the organisation of the Division and publications written by the staff are listed. (U.K.)

  4. Radiation emergencies

    International Nuclear Information System (INIS)

    Elaborate precautions are taken in the design, construction and operation of nuclear installations. Even then, there always remains the possibility, however small, of accidents. A radiation emergency can be defined as any abnormal situation following an incident/accident which may result in either unusually large radiation fields in any plant/area or large release of air or liquid borne radioactivity leading to widespread contamination of areas

  5. Synchrotron radiation

    International Nuclear Information System (INIS)

    The paper on synchrotron radiation is the appendix to the Daresbury (United Kingdom) annual report, 1985/86. The bulk of the volume is made up of the progress reports for the work carried out during the year under review using the Synchrotron Radiation Source (SRS) at Daresbury. The Appendix also contains: the scientific programmes at the the SRS, progress on beamlines, instrumentation and computing developments, and activities connected with accelerator development. (U.K.)

  6. Radiation Protection

    International Nuclear Information System (INIS)

    Major achievements of SCK-CEN's Radiation Protection Department in 2000 are described. The main areas for R and D of the department remain neutron dosimetry and neutron activation analysis, safeguards information handling and non-destructive assay techniques. Further activities include low-level radioactivity measurements in environmental and biological samples and radiation protection research. Finally, achievements in decision strategy research and social sciences in nuclear research are reported

  7. Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  8. Radiation Entomology

    OpenAIRE

    A. Nagaratnam

    2000-01-01

    The article reviews the use of radiation and radioisotopes in entomology with special reference to the use of radiotracers in entomological studies and the use of sterile insect techniques in the control of insect pests. It also presents' a profile of Shri Koshy and his contributions to defence entomology, including design of an efficient device for the rearing of cockroaches, evaluation of different repellents against leeches, laboratory and pilot field studies on the use of radiation-steril...

  9. Radiation dosimeters

    International Nuclear Information System (INIS)

    A radiation dosimeter is a device, instrument or system that measures or evaluates, either directly or indirectly, the quantities exposure, kerma, absorbed dose or equivalent dose, or their time derivatives (rates), or related quantities of ionizing radiation. A dosimeter along with its reader is referred to as a dosimetry system. Measurement of a dosimetric quantity is the process of finding the value of the quantity experimentally using dosimetry systems. The result of a measurement is the value of a dosimetric quantity expressed as the product of a numerical value and an appropriate unit. To function as a radiation dosimeter, the dosimeter must possess at least one physical property that is a function of the measured dosimetric quantity and that can be used for radiation dosimetry with proper calibration. In order to be useful, radiation dosimeters must exhibit several desirable characteristics. For example, in radiotherapy exact knowledge of both the absorbed dose to water at a specified point and its spatial distribution are of importance, as well as the possibility of deriving the dose to an organ of interest in the patient. In this context, the desirable dosimeter properties will be characterized by accuracy and precision, linearity, dose or dose rate dependence, energy response, directional dependence and spatial resolution. Obviously, not all dosimeters can satisfy all characteristics. The choice of a radiation dosimeter and its reader must therefore be made judiciously, taking into account the requirements of the measurement situation

  10. Prospective stratification of patients at risk for emergency department revisit: resource utilization and population management strategy implications

    OpenAIRE

    Jin, Bo; Zhao, Yifan; Hao, Shiying; Shin, Andrew Young; Wang, Yue; Zhu, Chunqing; Hu, Zhongkai; Fu, Changlin; Ji, Jun; Wang, Yong; Zhao, Yingzhen; Jiang, Yunliang; Dai, Dorothy; Culver, Devore S; Alfreds, Shaun T

    2016-01-01

    Background Estimating patient risk of future emergency department (ED) revisits can guide the allocation of resources, e.g. local primary care and/or specialty, to better manage ED high utilization patient populations and thereby improve patient life qualities. Methods We set to develop and validate a method to estimate patient ED revisit risk in the subsequent 6 months from an ED discharge date. An ensemble decision-tree-based model with Electronic Medical Record (EMR) encounter data from He...

  11. The Coral Data Time Series Need To Be Revisited

    Science.gov (United States)

    Juillet-Leclerc, A.

    2004-12-01

    Coral skeleton is formed under organism control and its geochemical properties are strongly influenced by biological effects embedding environmental signal. Geochemists have been puzzled by the diversity of geochemical responses showed by colonies grown in a same area. By revisiting the Weber and Woodhead data series (1972), gathering data from enough colonies developed in similar conditions to provide a statistical isotopic value representative of one site, we demonstrate that for Porites and Acropora, the expected isotopic thermometer is revealed when the "vital effect" is removed. On the other hand, by using Acropora cultured in controlled condition, with changing temperature on a range comprised between 23 and 29°C, the comparison of oxygen and carbon isotopic values revealed the role played by kinetic fractionation. This apparent paradox of two co-existing fractionations is explained by the isotopic analyzes of wild and cultured corals operated at micrometer size scale taking into account of microstructures of the skeleton. Two different crystals appear to be the growth units of the skeleton, each crystal corresponding to a specific deposition mechanism. Thus, the measurement performed with a conventional method is a "bulk" measurement, which depends upon two isotopic fractionations. Some investigations underlined the discrepancy of the meaning of the inter-annual and seasonal isotopic records, which could be illustrated by different isotopic calibrations assessed from seasonal or annual data. It has been also explained by micrometer analyses of Porites aragonite. A smoothing at around 400microns of isotopic measurements as well as Sr/Ca indicates that at seasonal time scale the growth unit is the month. This is in agreement with extensive studies conducted by biologists describing the mechanism governing the formation of Porites skeleton: every month is deposited a framework which is progressively filled in. By combining biologists and geochemists knowledge

  12. The "frontal syndrome" revisited: lessons from electrostimulation mapping studies.

    Science.gov (United States)

    Duffau, Hugues

    2012-01-01

    For a long time, in a localizationist view of brain functioning, a combination of symptoms called "frontal syndrome" has been interpreted as the direct result of damages involving the frontal lobe(s). The goal of this review is to challenge this view, that is, to move to a hodotopical approach to lesion mapping, on the basis of new insights provided by intraoperative electrostimulation mapping investigations in patients who underwent awake surgery for cerebral tumors. These original data reported in the last decade break with the traditional dogma of a modular and fixed organization of the central nervous system, by switching to the concepts of cerebral connectivity and plasticity - i.e., a brain organization based on dynamic interrelationships between parallel distributed networks. According to this revisited model, "frontal symptoms" can be generated by tumor or electrostimulation not only of the frontal lobes, but also of cortical and subcortical (white matter pathways/deep gray nuclei) structures outside the frontal lobes: especially, stimulation of the superior longitudinal fascicle may elicit speech production disorders, syntactic disturbances, involuntary language switching or phonemic paraphasia (arcuate fascicle), stimulation of the inferior fronto-occipital fascicle can generate semantic paraphasia or deficit of cross-modal judgment, stimulation of the subcallosal fasciculus may elicit transcortical motor aphasia, while stimulation of the striatum induces preservations. On the other hand, it is also possible to perform extensive right or left frontal lobectomy in patients who continue to have a normal familial, social and professional life, without "frontal syndrome". Therefore, this provocative approach may open the door to a renewal in the modeling of brain processing as well as in its clinical applications, especially in the fields of cerebral surgery and functional rehabilitation. These findings illustrate well the need to reinforce links between

  13. Revisiting four scientific debates in ocean acidification research

    Directory of Open Access Journals (Sweden)

    A. J. Andersson

    2012-03-01

    Full Text Available In recent years, ocean acidification has gained continuously increasing attention from scientists and a number of stakeholders and has raised serious concerns about its effects on marine organisms and ecosystems. With the increase in interest, funding resources, and the number of scientific investigations focusing on this environmental problem, increasing amounts of data and results have been produced, and a progressively growing and more rigorous understanding of this problem has begun to develop. Nevertheless, there are still a number of scientific debates, and in some cases misconceptions, that keep reoccurring at a number of forums in various contexts. In this article, we revisit four of these topics that we think require further thoughtful consideration including: (1 surface seawater CO2 chemistry in shallow water coastal areas, (2 experimental manipulation of marine systems using CO2 gas or by acid addition, (3 net versus gross calcification and dissolution, and (4 CaCO3 mineral dissolution and seawater buffering. As a summation of these topics, we emphasize that: (1 many coastal environments experience seawater pCO2 that is significantly higher than expected from equilibrium with the atmosphere and is strongly linked to biological processes; (2 addition of acid, base or CO2 gas to seawater can all be useful techniques to manipulate seawater chemistry in ocean acidification experiments; (3 estimates of calcification or CaCO3 dissolution based on present techniques are measuring the net of gross calcification and dissolution; and (4 dissolution of metastable carbonate mineral phases will not produce sufficient alkalinity to buffer the pH and carbonate saturation state of shallow water environments on timescales of decades to hundreds of years to the extent that any potential negative effects on marine calcifiers will be avoided.

  14. Memory Revisited in Julian Barnes's "The Sense of an Ending"

    Directory of Open Access Journals (Sweden)

    Maricel Oró Piqueras

    2014-01-01

    Full Text Available An accumulation of years brings with it an accumulation of experiences. The revision of such experiences usually becomes more recurrent after retiremen t, a transition time from one period of life to another and, as such, a time in which we, human being s, have a tendency to take stock of our lives. This is actually one of the main issues present in Julian Barnes's last novel The Sense of an Ending (2011 . When the main protagonist, a retired man quite comfortable and contented with his present life, receives an unexpected inheritance from the mother of a girlfriend from his university years, he is forced to track down a part of his life that he had left a t the back of his mind a long time ago. As he explains his story, the protagonist and narrator of the novel raises a number of questions related to the quality and func tion of memory as one gets into old age . He experiments the unreliability of memory and questions to what extent me mory is constructed through the remembered emotions that invaded him over that episode of his life rather than through the events as they actually took place. On the other hand, the act of revisiting and revising that specific ep isode, brings with it feelings of guilt and remorse as the protagonist realises that his past acts were not as noble as he remembered them to be. However, these acts are part of the past and they cannot be changed; thus, another question that the novel rai ses is how to account for those actions of which one does not feel proud and, more importantly, how to manage those bad memories as one gets older.

  15. Simultaneous extratympanic electrocochleography and auditory brainstem responses revisited

    Directory of Open Access Journals (Sweden)

    Carlos Minaya

    2015-03-01

    Full Text Available The purpose of this study was to revisit the two-channel, simultaneous click-evoked extratympanic electrocochleography and auditory brainstem response (ECoG/ABR recording technique for clinical use in normal hearing participants. Recording the compound action potential (AP of the ECoG simultaneously with ABR may be useful when Wave I of the ABR is small or diminished in patients with sensorineural or retrocochlear disorder and minimizes overall test time. In contrast to some previous studies that used the extratympanic electrode both as non-inverting electrode for the ECoG and inverting electrode for ABR, this study maintained separate recording channel montages unique to conventional click-evoked ECoG and ABR recordings. That is, the ABR was recorded using a vertical channel (Cz to ipsilateral earlobe, while the ECoG with custom extratympanic electrode was recorded using a horizontal channel (tympanic membrane to contralateral earlobe. The extratympanic electrode is easy to fabricate inhouse, or can be purchased commercially. Maintaining the conventional ABR montage permits continued use of traditional normative data. Broadband clicks at a fixed level of 85 dB nHL were presented with alternating polarity at stimulus rates of 9.3, 11.3, and 15.3/s. Different stimulation rates were explored to identify the most efficient rate without sacrificing time or waveform morphology. Results revealed larger ECoG AP than ABR Wave I, as expected, and no significant difference across stimulation rate and no interaction effect. Extratympanic electrode placement takes little additional clinic time and may improve the neurodiagnostic utility of the ABR.

  16. Revisiting noninteracting string partition functions in Rindler space

    Science.gov (United States)

    Mertens, Thomas G.; Verschelde, Henri; Zakharov, Valentin I.

    2016-05-01

    We revisit noninteracting string partition functions in Rindler space by summing over fields in the spectrum. In field theory, the total partition function splits in a natural way into a piece that does not contain surface terms and a piece consisting of solely the so-called edge states. For open strings, we illustrate that surface contributions to the higher-spin fields correspond to open strings piercing the Rindler origin, unifying the higher-spin surface contributions in string language. For closed strings, we demonstrate that the string partition function is not quite the same as the sum over the partition functions of the fields in the spectrum: an infinite overcounting is present for the latter. Next we study the partition functions obtained by excluding the surface terms. Using recent results of He et al. [J. High Energy Phys. 05 (2015) 106], this construction, first done by Emparan [arXiv:hep-th/9412003], can be put on much firmer ground. We generalize to type II and heterotic superstrings and demonstrate modular invariance. All of these exhibit an IR divergence that can be interpreted as a maximal acceleration close to the black hole horizon. Ultimately, since these partition functions are only part of the full story, divergences here should not be viewed as a failure of string theory: maximal acceleration is a feature of a faulty treatment of the higher-spin fields in the string spectrum. We comment on the relevance of this to Solodukhin's recent proposal [Phys. Rev. D 91, 084028 (2015)]. A possible link with the firewall paradox is apparent.

  17. Revisiting the OH-CH correlation in diffuse clouds

    Science.gov (United States)

    Mookerjea, Bhaswati

    2016-04-01

    Based on the analysis of available published data and archival data along 24 sightlines (5 of which are new) we derive more accurate estimates of the column densities of OH and CH towards diffuse/translucent clouds and revisit the typically observed correlation between the abundances of these species. The increase in the sample size was possible because of the equivalence of the column densities of CH derived from a combination of the transitions at 3137 & 3143 Å, and a combination of transitions at 3886 & 3890 Å, which we have demonstrated here. We find that with the exception of four diffuse clouds, the entire source sample shows a clear correlation between the column densities of OH and CH similar to previous observations. The analysis presented also verifies the theoretically predicted oscillator strengths of the OH A-X (3078 & 3082 Å), CH B-X (3886 & 3890 Å) and C-X (3137 & 3143Å) transitions. We estimate N(H) and N(H2) from the observed E(B - V) and N(CH) respectively. The N(OH)/N(CH) ratio is not correlated with the molecular fraction of hydrogen in the diffuse/translucent clouds. We show that with the exception of HD 34078 for all the clouds the observed column density ratios of CH and OH can be reproduced by simple chemical models which include gas-grain interaction and gas-phase chemistry. The enhanced N(OH)/N(CH) ratio seen towards the 3 new sightlines can be reproduced primarily by considering different cosmic ray ionization rates.

  18. Memory Revisited in Julian Barnes's The Sense of an Ending

    Directory of Open Access Journals (Sweden)

    Maricel Oró Piqueras

    2014-02-01

    Full Text Available An accumulation of years brings with it an accumulation of experiences. The revision of such experiences usually becomes more recurrent after retirement, a transition time from one period of life to another and, as such, a time in which we, human beings, have a tendency to take stock of our lives. This is actually one of the main issues present in Julian Barnes's last novel The Sense of an Ending (2011. When the main protagonist, a retired man quite comfortable and contented with his present life, receives an unexpected inheritance from the mother of a girlfriend from his university years, he is forced to track down a part of his life that he had left at the back of his mind a long time ago. As he explains his story, the protagonist and narrator of the novel raises a number of questions related to the quality and function of memory as one gets into old age. He experiments the unreliability of memory and questions to what extent memory is constructed through the remembered emotions that invaded him over that episode of his life rather than through the events as they actually took place. On the other hand, the act of revisiting and revising that specific episode, brings with it feelings of guilt and remorse as the protagonist realises that his past acts were not as noble as he remembered them to be. However, these acts are part of the past and they cannot be changed; thus, another question that the novel raises is how to account for those actions of which one does not feel proud and, more importantly, how to manage those bad memories as one gets older

  19. The Lumbar Lordosis in Males and Females, Revisited.

    Directory of Open Access Journals (Sweden)

    Ori Hay

    Full Text Available Whether differences exist in male and female lumbar lordosis has been debated by researchers who are divided as to the nature of variations in the spinal curve, their origin, reasoning, and implications from a morphological, functional and evolutionary perspective. Evaluation of the spinal curvature is constructive in understanding the evolution of the spine, as well as its pathology, planning of surgical procedures, monitoring its progression and treatment of spinal deformities. The aim of the current study was to revisit the nature of lumbar curve in males and females.Our new automated method uses CT imaging of the spine to measure lumbar curvature in males and females. The curves extracted from 158 individuals were based on the spinal canal, thus avoiding traditional pitfalls of using bone features for curve estimation. The model analysis was carried out on the entire curve, whereby both local and global descriptors were examined in a single framework. Six parameters were calculated: segment length, curve length, curvedness, lordosis peak location, lordosis cranial peak height, and lordosis caudal peak height.Compared to males, the female spine manifested a statistically significant greater curvature, a caudally located lordotic peak, and greater cranial peak height. As caudal peak height is similar for males and females, the illusion of deeper lordosis among females is due partially to the fact that the upper part of the female lumbar curve is positioned more dorsally (more backwardly inclined.Males and females manifest different lumbar curve shape, yet similar amount of inward curving (lordosis. The morphological characteristics of the female spine were probably developed to reduce stress on the vertebral elements during pregnancy and nursing.

  20. CHS基因起源初探及其在被子植物中的进化分析%A Preliminary Study on the Origin and Evolution of Chalcone Synthase (CHS) Gene in Angiosperms

    Institute of Scientific and Technical Information of China (English)

    黄金霞; 瞿礼嘉; 杨继; 银好; 顾红雅

    2004-01-01

    nudum (L.) Griseb. and Equisetum arvense L., as outgroups, the phylogenetic trees of about 250 CHSs from 29 families of angiosperm plants were constructed by using the neighbour-joining (NJ), maximum parsimony (MP) and quartet puzzle (QP)methods. The results showed that the CHSs from most plant families were separated into two or more clades while sequences from the families Brassicaceae, Fabaceae and Poaceae were each grouped into an independent monophyletic clade. The relative base substitution rates were estimated for CHS genes in three plant families, Solanaceae, Convolvulaceae, and Asteraceae, where the heterogeneity rate was detected both within and among the families. Results indicated that CHS genes in angiosperm plants were greatly diverse in terms of copy number, base substitution rate, and duplication/deletion events, which might be correlated with the diversity of life history, habitat, floral characters, and defense system of angiosperm plants.

  1. Radiation enteritis and radiation scoliosis

    Energy Technology Data Exchange (ETDEWEB)

    Shah, M.; Eng, K.; Engler, G.L.

    1980-09-01

    Any patient with radiation scoliosis should be suspected of having a visceral lesion as well. Chronic radiation enteritis may be manifested by intestinal obstruction, fistulas, perforation, and hemorrhage. Intestinal obstruction is the most common complication, and must be differentiated from postoperative cast or from spinal-traction syndrome. Obstruction that does not respond promptly to conservative measures must be treated surgically. Irradiated bowel is ischemic, and necrosis with spontaneous perforation can only be avoided with early diagnosis and surgical intervention.

  2. Radiation enteritis and radiation scoliosis

    International Nuclear Information System (INIS)

    Any patient with radiation scoliosis should be suspected of having a visceral lesion as well. Chronic radiation enteritis may be manifested by intestinal obstruction, fistulas, perforation, and hemorrhage. Intestinal obstruction is the most common complication, and must be differentiated from postoperative cast or from spinal-traction syndrome. Obstruction that does not respond promptly to conservative measures must be treated surgically. Irradiated bowel is ischemic, and necrosis with spontaneous perforation can only be avoided with early diagnosis and surgical intervention

  3. Radiation cataract

    International Nuclear Information System (INIS)

    Until very recently, ocular exposure guidelines were based on the assumption that radiation cataract is a deterministic event requiring threshold doses generally greater than 2 Gy. This view was, in part, based on older studies which generally had short follow-up periods, failed to take into account increasing latency as dose decreased, had relatively few subjects with doses below a few Gy, and were not designed to detect early lens changes. Newer findings, including those in populations exposed to much lower radiation doses and in subjects as diverse as astronauts, medical workers, atomic bomb survivors, accidentally exposed individuals, and those undergoing diagnostic or radiotherapeutic procedures, strongly suggest dose-related lens opacification at significantly lower doses. These observations resulted in a recent re-evaluation of current lens occupational exposure guidelines, and a proposed lowering of the presumptive radiation cataract threshold to 0.5 Gy/year and the occupational lens exposure limit to 20 mSv/year, regardless of whether received as an acute, protracted, or chronic exposure. Experimental animal studies support these conclusions and suggest a role for genotoxicity in the development of radiation cataract. Recent findings of a low or even zero threshold for radiation-induced lens opacification are likely to influence current research efforts and directions concerning the cellular and molecular mechanisms underlying this pathology. Furthermore, new guidelines are likely to have significant implications for occupational and/or accidental exposure, and the need for occupational eye protection (e.g. in fields such as interventional medicine).

  4. Radiation myelopathy

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, I.A.; Myers, S.J.

    1976-02-01

    Myelopathy secondary to radiation is a relatively uncommon entity which was reported initially in 1941 by Ahlbom. From a total of 65 patients who were seen in our spinal injury clinic during the past four years, three patients have received a diagnosis of radiation myelopathy. This is 4.6 percent of the total number. The case histories of two patients with radiation myelopathy are presented. The clinical and pathologic features are discussed. Since the three patients with this diagnosis whose cases are followed in the clinic are still alive, the second case that is reported is taken from the files of the pathology department so that autopsy and histologic data also can be presented.

  5. Radiation myelopathy

    International Nuclear Information System (INIS)

    Myelopathy secondary to radiation is a relatively uncommon entity which was reported initially in 1941 by Ahlbom. From a total of 65 patients who were seen in our spinal injury clinic during the past four years, three patients have received a diagnosis of radiation myelopathy. This is 4.6 percent of the total number. The case histories of two patients with radiation myelopathy are presented. The clinical and pathologic features are discussed. Since the three patients with this diagnosis whose cases are followed in the clinic are still alive, the second case that is reported is taken from the files of the pathology department so that autopsy and histologic data also can be presented

  6. Radiation gauge

    International Nuclear Information System (INIS)

    Fuji Electric has developed a pipe wall thinning detection device, which operates based on radiation gauge technology, for use in nuclear power plants and thermoelectric power plants. The radiation from the pipe wall thinning detection device, which can be used even during the plant operation, can penetrate heat insulation material. The device consists of detector and radiation source, and can detect the thickness of pipes (less than 500 mm in external diameter and less than 50 mm in thickness) with 2% reproducibility (with a measurement time of several minutes), based on the attenuation rate. Operation is easy and efficient since there is no need to remove the heat insulation and it is easy to mount the device, thus enabling more effective detection. (author)

  7. Synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation has had a revolutionary effect on a broad range of scientific studies, from physics, chemistry and metallurgy to biology, medicine and geoscience. The situation during the last decade has been one of very rapid growth, there is a great vitality to the field and a capability has been given to a very broad range of scientific disciplines which was undreamt of just a decade or so ago. In this paper, the authors discuss some of the properties of synchrotron radiation that makes it so interesting and something of the sources in existence today including the National Synchrotron Light Source (NSLS). The NSLS is one of the new facilities built specifically for synchrotron radiation research and the model that was developed there for involvement of the scientific community is a good one which provides some good lessons for these facilities and others

  8. Synchrotron radiation

    International Nuclear Information System (INIS)

    Synchrotron radiation (SR) from the bending magnet of a circular electron (positron) accelerator is a brilliant source in the vacuum ultraviolet, soft- and hard-x ray regions. First the characteristics of the bending SR are delete discussed. Though the brilliance of SR was improved dramatically in the last decade, neither bending, wiggler SR nor undulator SR is coherent. Coherent far infrared radiation in the mm wavelength region has recently been observed from a short electron bunch (∼ 2.5 mm long) in a bending magnet connected to a linac at Tohoku University. Coherent radiation due to higher harmonics generation by laser excitation of electron bunches in an undulator is then described. Finally a free electron laser (FEL) using optical klystron in a storage ring is reviewed. (author)

  9. CSR-induced emittance growth in achromats: Linear formalism revisited

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.

    2015-09-11

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  10. CSR-induced emittance growth in achromats: Linear formalism revisited

    Science.gov (United States)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  11. Radiation risks

    International Nuclear Information System (INIS)

    This report contains an evaluation of data available about the deleterious effects of exposure of people to ionising radiation, assuming that the total exposure is low (low dose) or that exposure to dose takes place gradually (low dose rate). It is a revision of the 1985 Health Council report on 'The scientific foundations for radiation protection policy based on the UNSCEAR-77, -82, and BEIR reports'. The report is also meant to be a reply to a request for advice made by the Minister of Welfare, Public Health and Culture in 1989. Scientific opinion on induction of cancer by radiation has clearly changed since 1988. This is a consequence of new publications of epidemiological studies among survivors of the atomic explosions of Hiroshima and Nagasaki. The Committee that has produced the present report has paid much attention to this development. Besides, in the request for advice just mentioned it is asked whether the margins of uncertainty which complicated the quantitative assessment of the radiation risk can be reduced. Consequently the Committee has dealt extensively with the potential errors and uncertainties in available data. Especially these 2 elements - a careful consideration of a recent shift in scientific opinion and a constant attention for the magnitude of potential uncertainties - have had a predominant influence on the content and design of this report. The Committee has tried to answer as fully as possible the complex question how to transform results of scientific research into a well-organised data set on which the government can base its radiation protection policy. The Committee had also compared its evaluation to the recent recommendations of the International Commission on Radiological Protection (ICRP) and the points of view of the Dutch policy directive 'Dealing with radiation risks'. (author). 111 refs.; 12 tabs

  12. Radiation control

    International Nuclear Information System (INIS)

    This paper describes on how the condition of radiation level in the ring (storage ring) experimentation room changes corresponding to the operating stage of SOR-ring (synchrotron radiation storage ring), and does not describe on the present radiation control in the SOR facility. The operating stage of SOR is divided into the following five: (1) 307 MeV electron injection, (2) 307 MeV electron storage (used for SOR experiments), (3) energy increase from 307 to 380 MeV, (4) 380 MeV electron storage, (5) re-injection and completion of operation. Gamma and X ray levels are shown when electron beam is injected from the electron synchrotron to the SOR-ring. Two main causes of the high level are reported. Spatial dose rate in storing 307 MeV electrons in also illustrated. This is sufficiently lower than that at electron incidence. The measurement of radiation level at the time of energy increase from 307 to 380 MeV has just started. Since the radiation level in 380 MeV storage, measured at the points about 20 cm apart from the electron orbit, showed several mR/h, the level seems to be negligible at the points where experiments are carried out, 1 m away from the measurement points. The radiation level in electron reinjection and completion of operation may be large during a short period (a few Roentgen) like the time of energy increase. Therefore, the beam shall be re-injected or decreased after confirming that all experimenters have retreated into the predetermined place. (Wakatsuki, Y.)

  13. Radiation dermatitis

    International Nuclear Information System (INIS)

    Even in this era of modern radiotherapy, injuries associated with the medical and industrial use of radiation devices will continue to pose a difficult problem for the reconstructive surgeon. It must be borne in mind that the single most serious hazard to surgery in irradiated tissue is the lodgement of bacteria in tissue rendered avascular by the radiation and the secondary necrosis from the infection itself. The basic principles of wound management must be augmented by thorough knowledge of the use of well-vascularized muscle and musculocutaneous flap to provide adequate, blood-rich, soft-tissue coverage

  14. Radiation toxicology

    International Nuclear Information System (INIS)

    The extensive studies on both human and experimental animal populations have provided information that allows radiation protection standards to be set with greater confidence than for most if not all other carcinogenic agents. Furthermore, both international and national advisory bodies are continually updating the risk estimates and the standards as new information is available. However, it is clear that we need models that take into account the multistage nature of carcinogenesis. Studies in both ionizing and ultraviolet radiation carcinogenesis are more valuable to the general problem of elucidating the mechanisms involved in cancer than is indicated by the amount of work or support for this field of research

  15. Radiation Entomology

    Directory of Open Access Journals (Sweden)

    A. Nagaratnam

    2000-10-01

    Full Text Available The article reviews the use of radiation and radioisotopes in entomology with special reference to the use of radiotracers in entomological studies and the use of sterile insect techniques in the control of insect pests. It also presents' a profile of Shri Koshy and his contributions to defence entomology, including design of an efficient device for the rearing of cockroaches, evaluation of different repellents against leeches, laboratory and pilot field studies on the use of radiation-sterilised males for the control of the mosquito Culex fatigans.

  16. Radiation toxicology

    International Nuclear Information System (INIS)

    Extensive studies on both human and experimental animal populations have provided information that allow radiation protection standards to be set with greater confidence than for most if not all other carcinogenic agents. Furthermore, both international and national advisory bodies are continually updating the risk estimates and the standards as new information is available. However, it is clear that models are needed that take into account the multistage nature of carcinogenesis. Studies in both ionizing and ultraviolet radiation carcinogenesis are more valuable to the general problem of elucidating the mechanisms involved in cancer than is indicated by the amount of work or support for this field of research

  17. Thermal radiation of Er doped dielectric crystals: Probing the range of applicability of the Kirchhoff law

    CERN Document Server

    Tanyi, Ekembu K; Narimanov, Evgenii E; Noginov, M A

    2016-01-01

    The Kirchhoff law of thermal radiation, relating emissivity {\\epsilon} and absorptance {\\alpha}, has been originally formulated for opaque bodies in thermodynamic equilibrium with the environment. However, in many systems of practical importance, both assumptions are often not satisfied. In this work, we revisit the century-old law and examine the limits of its applicability in an example of Er:YAG and Er:YLF dielectric crystals, potential radiation converters for thermophotovoltaic applications. In our experiments, the (80 at.%) Er:YAG crystal was opaque between 1.45 {\\mu}m and 1.64 {\\mu}m. In this spectral range, its absorptance {\\alpha}({\\lambda}) is spectrally flat and differentiates from unity only by a small amount of reflection. The shape of the emissivity spectrum {\\epsilon}({\\lambda}) closely matches that of absorptance {\\alpha}({\\lambda}), suggesting that the Kirchhoff law can adequately describe thermal radiation of opaque bodies, even if the requirement of thermodynamic equilibrium is not satisfie...

  18. Line Emission from Radiation-Pressurized HII Region II: Dynamics and Population Synthesis

    CERN Document Server

    Verdolini, Silvia; Krumholz, Mark R; Matzner, Christopher D; Tielens, Alexander G G M

    2013-01-01

    Optical and infrared emission lines from HII regions are an important diagnostic used to study galaxies, but interpretation of these lines requires significant modeling of both the internal structure and dynamical evolution of the emitting regions. Most of the models in common use today assume that HII region dynamics are dominated by the expansion of stellar wind bubbles, and have neglected the contribution of radiation pressure to the dynamics, and in some cases also to the internal structure. However, recent observations of nearby galaxies suggest that neither assumption is justified, motivating us to revisit the question of how HII region line emission depends on the physics of winds and radiation pressure. In a companion paper we construct models of single HII regions including and excluding radiation pressure and winds, and in this paper we describe a population synthesis code that uses these models to simulate galactic collections of HII regions with varying physical parameters. We show that the choice...

  19. Radiation dosimetry

    International Nuclear Information System (INIS)

    Film is one of the most simple ways to detect radiation although for film as dosimeters a careful attention is required in many aspects, such as emulsion characteristics, film response capacity processing techniques and interpretation of the exposition. Surpassing these factors the film dosimeter is the most reliable

  20. Radiation dosage

    International Nuclear Information System (INIS)

    Radiation dosage at Bikini Atoll is the result of current soil contamination, a relic of the nuclear weapons testing program of some 30 years ago. The principal contaminants today and some of their physical properties are listed: cesium-137, strontium-90, plutonium -239, 240 and americium-241. Cobalt-60 contributes less than 1 to the dose and is not considered significant. A resident of the atoll would accumulate radiation dose (rem) in two ways -- by exposure to radiation emanating from the ground and vegetation, and by exposure to radiation released in the spontaneous decay of radionuclides that have entered his body during the ingestion of locally grown foods. The latter process would account for some 90% of the dose; cesium-137 would be responsible for 0 90% of it. Since BARC's method of estimating dosage differs in some respects from that employed by the Lawrence Livermore National Laboratory (LLNL), (Ref.1, LLNL 1982) we are presenting our method in detail. The differences have two sources. First, the numbers used by BARC for the daily ingestion of radionuclides via the diet are higher than LLNL's. Second, BARC's calculation of dose from radionuclide intake utilizes the ICRP system. The net result is that BARC doses are consistently higher than LLNL doses, and in this respect are more conservative

  1. Radiation Technology

    International Nuclear Information System (INIS)

    The conference was organized to evaluate the application directions of radiation technology in Vietnam and to utilize the Irradiation Centre in Hanoi with the Co-60 source of 110 kCi. The investigation and study of technico-economic feasibility for technology development to various items of food and non-food objects was reported. (N.H.A)

  2. SU-E-I-43: Photoelectric Cross Section Revisited

    International Nuclear Information System (INIS)

    Purpose: The importance of the precision in photoelectric cross-section value increases for recent developed technology such as dual energy computed tomography, in which some reconstruction algorithms require the energy dependence of the photo-absorption in each material composition of human being. In this study, we revisited the photoelectric cross-section calculation by self-consistent relativistic Hartree-Fock (HF) atomic model and compared with that widely distributed as “XCOM database” in National Institute of Standards and Technology, which was evaluated with localdensity approximation for electron-exchange (Fock)z potential. Methods: The photoelectric cross section can be calculated with the electron wave functions in initial atomic state (bound electron) and final continuum state (photoelectron). These electron states were constructed based on the selfconsistent HF calculation, where the repulsive Coulomb potential from the electron charge distribution (Hartree term) and the electron exchange potential with full electromagnetic interaction (Fock term) were included for the electron-electron interaction. The photoelectric cross sections were evaluated for He (Z=2), Be (Z=4), C (Z=6), O (Z=8), and Ne (Z=10) in energy range of 10keV to 1MeV. The Result was compared with XCOM database. Results: The difference of the photoelectric cross section between the present calculation and XCOM database was 8% at a maximum (in 10keV for Be). The agreement tends to be better as the atomic number increases. The contribution from each atomic shell has a considerable discrepancy with XCOM database except for K-shell. However, because the photoelectric cross section arising from K-shell is dominant, the net photoelectric cross section was almost insensitive to the different handling in Fock potential. Conclusion: The photoelectric cross-section program has been developed based on the fully self-consistent relativistic HF atomic model. Due to small effect on the Fock

  3. Consensus Paper: Revisiting the Symptoms and Signs of Cerebellar Syndrome.

    Science.gov (United States)

    Bodranghien, Florian; Bastian, Amy; Casali, Carlo; Hallett, Mark; Louis, Elan D; Manto, Mario; Mariën, Peter; Nowak, Dennis A; Schmahmann, Jeremy D; Serrao, Mariano; Steiner, Katharina Marie; Strupp, Michael; Tilikete, Caroline; Timmann, Dagmar; van Dun, Kim

    2016-06-01

    The cerebellum is involved in sensorimotor operations, cognitive tasks and affective processes. Here, we revisit the concept of the cerebellar syndrome in the light of recent advances in our understanding of cerebellar operations. The key symptoms and signs of cerebellar dysfunction, often grouped under the generic term of ataxia, are discussed. Vertigo, dizziness, and imbalance are associated with lesions of the vestibulo-cerebellar, vestibulo-spinal, or cerebellar ocular motor systems. The cerebellum plays a major role in the online to long-term control of eye movements (control of calibration, reduction of eye instability, maintenance of ocular alignment). Ocular instability, nystagmus, saccadic intrusions, impaired smooth pursuit, impaired vestibulo-ocular reflex (VOR), and ocular misalignment are at the core of oculomotor cerebellar deficits. As a motor speech disorder, ataxic dysarthria is highly suggestive of cerebellar pathology. Regarding motor control of limbs, hypotonia, a- or dysdiadochokinesia, dysmetria, grasping deficits and various tremor phenomenologies are observed in cerebellar disorders to varying degrees. There is clear evidence that the cerebellum participates in force perception and proprioceptive sense during active movements. Gait is staggering with a wide base, and tandem gait is very often impaired in cerebellar disorders. In terms of cognitive and affective operations, impairments are found in executive functions, visual-spatial processing, linguistic function, and affective regulation (Schmahmann's syndrome). Nonmotor linguistic deficits including disruption of articulatory and graphomotor planning, language dynamics, verbal fluency, phonological, and semantic word retrieval, expressive and receptive syntax, and various aspects of reading and writing may be impaired after cerebellar damage. The cerebellum is organized into (a) a primary sensorimotor region in the anterior lobe and adjacent part of lobule VI, (b) a second sensorimotor

  4. Revisiting Scaling Relations for Giant Radio Halos in Galaxy Clusters

    Science.gov (United States)

    Cassano, R.; Ettori, S.; Brunetti, G.; Giacintucci, S.; Pratt, G. W.; Venturi, T.; Kale, R.; Dolag, K.; Markevitch, Maxim L.

    2013-01-01

    Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R(sub 500) as P(sub 1.4) approx. L(2.1+/-0.2) - 500). Our bigger and more homogenous sample confirms that the X-ray luminous (L(sub 500) > 5 × 10(exp 44) erg/s)) clusters branch into two populations-radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P(sub 1.4) scales with the cluster integrated SZ signal within R(sub 500), measured by Planck, as P(sub 1.4) approx. Y(2.05+/-0.28) - 500), in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that "SZ-luminous" Y(sub 500) > 6×10(exp -5) Mpc(exp 2) clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle acceleration.

  5. Hydrodynamic limit of Wigner-Poisson kinetic theory: Revisited

    International Nuclear Information System (INIS)

    In this paper, we revisit the hydrodynamic limit of the Langmuir wave dispersion relation based on the Wigner-Poisson model in connection with that obtained directly from the original Lindhard dielectric function based on the random-phase-approximation. It is observed that the (fourth-order) expansion of the exact Lindhard dielectric constant correctly reduces to the hydrodynamic dispersion relation with an additional term of fourth-order, beside that caused by the quantum diffraction effect. It is also revealed that the generalized Lindhard dielectric theory accounts for the recently discovered Shukla-Eliasson attractive potential (SEAP). However, the expansion of the exact Lindhard static dielectric function leads to a k4 term of different magnitude than that obtained from the linearized quantum hydrodynamics model. It is shown that a correction factor of 1/9 should be included in the term arising from the quantum Bohm potential of the momentum balance equation in fluid model in order for a correct plasma dielectric response treatment. Finally, it is observed that the long-range oscillatory screening potential (Friedel oscillations) of type cos(2kFr)/r3, which is a consequence of the divergence of the dielectric function at point k = 2kF in a quantum plasma, arises due to the finiteness of the Fermi-wavenumber and is smeared out in the limit of very high electron number-densities, typical of white dwarfs and neutron stars. In the very low electron number-density regime, typical of semiconductors and metals, where the Friedel oscillation wavelength becomes much larger compared to the interparticle distances, the SEAP appears with a much deeper potential valley. It is remarked that the fourth-order approximate Lindhard dielectric constant approaches that of the linearized quantum hydrodynamic in the limit if very high electron number-density. By evaluation of the imaginary part of the Lindhard dielectric function, it is shown that the Landau-damping region in

  6. Characteristics of Cherenkov radiation in naturally occurring ice

    Science.gov (United States)

    Mikkelsen, R. E.; Poulsen, T.; Uggerhøj, U. I.; Klein, S. R.

    2016-03-01

    We revisit the theory of Cherenkov radiation in uniaxial crystals. Historically, a number of flawed attempts have been made at explaining this radiation phenomenon, and a consistent error-free description is nowhere available. We apply our calculation to a large modern day telescope—IceCube. Located in Antarctica, this detector makes use of the naturally occurring ice as a medium to generate Cherenkov radiation. However, due to the high pressure at the depth of the detector site, large volumes of hexagonal ice crystals are formed. We calculate how this affects the Cherenkov radiation yield and angular dependence. We conclude that the effect is small, at most about a percent, and would only be relevant in future high-precision instruments like e.g. Precision IceCube Next Generation Upgrade (PINGU). For radio-Cherenkov experiments which use the presence of a clear Cherenkov cone to determine the arrival direction, any variation in emission angle will directly and linearly translate into a change in apparent neutrino direction. In closing, we also describe a simple experiment to test this formalism and calculate the impact of anisotropy on light yields from lead tungstate crystals as used, for example, in the CMS calorimeter at the CERN LHC.

  7. Characteristics of Cherenkov Radiation in Naturally Occuring Ice

    CERN Document Server

    Mikkelsen, R E; Uggerhøj, U I; Klein, S R

    2016-01-01

    We revisit the theory of Cherenkov radiation in uniaxial crystals. Historically, a number of flawed attempts have been made at explaining this radiation phenomenon and a consistent error-free description is nowhere available. We apply our calculation to a large modern day telescope - IceCube. Being located at the Antarctica, this detector makes use of the naturally occuring ice as a medium to generate Cherenkov radiation. However, due to the high pressure at the depth of the detector site, large volumes of hexagonal ice crystals are formed. We calculate how this affects the Cherenkov radiation yield and angular dependence. We conclude that the effect is small, at most about a percent, and would only be relevant in future high precision instruments like e.g. Precision IceCube Next Generation Upgrade (PINGU). For radio-Cherenkov experiments which use the presence of a clear Cherenkov cone to determine the arrival direction, any variation in emission angle will directly and linearly translate into a change in ap...

  8. Radiation effects and radiation risks

    International Nuclear Information System (INIS)

    The book presents the facts and the principles of assessment and evaluation of biological radiation effects in general and also with particular reference to the reactor accident of Chernobyl, reviewing the consequences and the environmental situation on the basis of current national and international literature, including research work by the authors. The material compiled in this book is intended especially for physicians, but will also prove useful for persons working in the public health services, in administration, or other services taking care of people. The authors tried to find an easily comprehensible way of presenting and explaining the very complex processes and mechanisms of biological radiation effects and carcinogenesis, displaying the physical primary processes and the mechanisms of the molecular radiation effects up to the effects of low-level radiation, and present results of comparative epidemiologic studies. This section has been given considerable space, in proportion to its significance. It also contains literature references for further reading, offering more insight and knowledge of aspects of special subject fields. The authors also present less known results and data and discuss them against the background of well-known research results and approaches. Apart from the purpose of presenting comprehensive information, the authors intend to give an impact for further thinking about the problems, and helpful tools for independent decisions and action on the basis of improved insight and assessment, and in this context particularly point to the problems induced by the Chernobyl reactor accident. (orig./MG) With 8 maps in appendix

  9. Interpretation of transport barriers and of subneoclassical transport in the framework of the revisited neoclassical theory

    International Nuclear Information System (INIS)

    'Subneoclassical' heat fluxes are predicted in the high collisionality regime by the revisited neoclassical theory, which includes the roles of Finite Larmor Radius effects and Inertia, that we published earlier. Unlike conventional neoclassical theory, the revisited theory further provides a non degenerate ambipolarity constraint which defines unambiguously the radial electric field. Together with the parallel momentum equation, the ambipolarity constraint leads, under some conditions, to radial electric field profiles with high negative shear akin to those observed in spontaneous edge transport barriers. The predictions of the theory are outlined, with emphasis laid on the interpretation of experimental results such as magnitude of the jumps, width of the shear layer, local scaling laws. Extension of the theory to triggered transitions and cold pulse propagation studies is suggested. (author)

  10. Revisiting a fundamental test of the disc instability model for X-ray binaries

    OpenAIRE

    Coriat, M.; Fender, R. P.; Dubus, G.

    2012-01-01

    We revisit a core prediction of the disc instability model (DIM) applied to X-ray binaries. The model predicts the existence of a critical mass transfer rate, which depends on disc size, separating transient and persistent systems. We therefore selected a sample of 52 persistent and transient neutron star and black hole X-ray binaries and verified if observed persistent (transient) systems do lie in the appropriate stable (unstable) region of parameter space predicted by the model. We find th...

  11. The Probability of Transition to Entrepreneurship Revisited: Wealth, Education and Age

    OpenAIRE

    Mondragon-Velez, Camilo

    2009-01-01

    This paper revisits the empirical relationship between the probability of transition to entrepreneurship and wealth. Given that wealth is correlated with both education and age, these observable characteristics cannot be treated as independent covariates in the estimation. Thus, I document the differences in the transition probability profile across age and education groups. The main result of this paper is that the estimated probability of transition to entrepreneurship is hump-shaped in wea...

  12. Direct synthesis of 1,5-disubstituted-4-magnesio-1,2,3-triazoles, revisited.

    Science.gov (United States)

    Krasiński, Antoni; Fokin, Valery V; Sharpless, K Barry

    2004-04-15

    After revisiting earlier works reporting the regioselective synthesis of 1,5-disubstituted-1,2,3-triazoles via the addition of bromomagnesium acetylides to azides, much improved yields of the products were obtained for a wide array of azides and alkynes. The intermediates of that reaction can be trapped with different electrophiles to regioselectively form 1,4,5-trisubstituted 1,2,3-triazoles. [reaction: see text] PMID:15070306

  13. Revisiting the fundamental physical chemistry in heterogeneous photocatalysis : its thermodynamics and kinetics

    OpenAIRE

    Ohtani, Bunsho

    2014-01-01

    Although the history of photocatalysis research is not so long, many researchers have studied photocatalysis and a large number of papers on photocatalysis have been published. The objectives of this review paper are to revisit the fundamentals of photocatalysis, especially its thermodynamics and kinetics, which have not been reexamined in recent studies, to clarify the problems, if any, that prevent developments in the field of photocatalysis, and to present insights for future progress.

  14. Revisiting T2KK and T2KO physics potential and $\

    CERN Document Server

    Hagiwara, Kaoru; Okamura, Naotoshi; Takaesu, Yoshitaro

    2016-01-01

    We revisit the sensitivity study of the Tokai-to-Kamioka-and-Korea (T2KK) and Tokai-to-Kamioka-and-Oki (T2KO) proposals where a water Cerenkov detector with the 100 kton fiducial volume is placed in Korea ($L = 1000$ km) and Oki island ($L = 653$ km) in Japan, respectively, in addition to the Super-Kamiokande for determination of the neutrino mass hierarchy and leptonic CP phase ($\\delta_{CP}$). We systematically study the running ratio of the $\

  15. Is Sky the Limit? Revisiting ‘Exogenous Productivity of Judges’ Argument

    OpenAIRE

    Kamil Jonski; Daniel Mankowski

    2014-01-01

    This paper revisits ‘exogenous productivity of judges’ hypothesis, laid down in numerous Law & Economics studies based on ‘production function’ approach. It states that judges confronted with growing caseload pressure, adjust their productivity thereby increasing number of resolved cases. We attribute such results to assumptions regarding the shape of court’s ‘production function’, and present alternative – hockey-stick ‘production function’ model, explicitly taking into account the time ...

  16. Amish Revisited: Next Generation Sequencing Studies of Psychiatric Disorders Among the Plain People

    OpenAIRE

    Hou, Liping; Faraci, Gloria; Chen, David T.W.; Kassem, Layla; Schulze, Thomas G.; Shugart, Yin Yao; McMahon, Francis J.

    2013-01-01

    The rapid development of next-generation sequencing (NGS) technology has led to renewed interest in the potential contribution of rarer forms of genetic variation to complex, non-Mendelian phenotypes, such as psychiatric illnesses. Although challenging, family-based studies offer some advantages, especially in communities with large families and a limited number of founders. Here we revisit family-based studies of mental illnesses in traditional Amish and Mennonite communities -- known collec...

  17. Lipoabdominoplasty: Revisiting the Superior Pull-Down Abdominal Flap and New Approaches

    OpenAIRE

    Uebel, Carlos Oscar

    2009-01-01

    Abdominoplasty is a very common procedure, especially for patients with abdominal laxness, striaes, and muscle rectus diastases. With the advent of liposuction 28 years ago, we can improve body contouring by treating lipodystrophies in the epigastric, flank, trochanteric, and buttocks areas. The procedure combining abdominoplasty and liposuction is called lipoabdominoplasty. Many new techniques have been proposed since these procedures were introduced; we now revisit the superior pull-down ab...

  18. The Revisiting Problem in Mobile Robot Map Building: A Hierarchical Bayesian Approach

    OpenAIRE

    Stewart, Benjamin; Ko, Jonathan; Fox, Dieter; Konolige, Kurt

    2012-01-01

    We present an application of hierarchical Bayesian estimation to robot map building. The revisiting problem occurs when a robot has to decide whether it is seeing a previously-built portion of a map, or is exploring new territory. This is a difficult decision problem, requiring the probability of being outside of the current known map. To estimate this probability, we model the structure of a "typical" environment as a hidden Markov model that generates sequences of views observed by a robot ...

  19. Lifted Representation of Relational Causal Models Revisited: Implications for Reasoning and Structure Learning

    OpenAIRE

    Lee, Sanghack; Honavar, Vasant

    2015-01-01

    Maier et al. (2010) introduced the relational causal model (RCM) for representing and inferring causal relationships in relational data. A lifted representation, called abstract ground graph (AGG), plays a central role in reasoning with and learning of RCM. The correctness of the algorithm proposed by Maier et al. (2013a) for learning RCM from data relies on the soundness and completeness of AGG for relational d-separation to reduce the learning of an RCM to learning of an AGG. We revisit the...

  20. Habituation Revisited: An Updated and Revised Description of the Behavioral Characteristics of Habituation

    OpenAIRE

    Rankin, Catharine H.; Abrams, Thomas; Barry, Robert J; Bhatnagar, Seema; Clayton, David; Colombo, John; Coppola, Gianluca; Geyer, Mark A.; David L Glanzman; Marsland, Stephen; McSweeney, Frances; Donald A Wilson; Wu, Chun-Fang; Thompson, Richard F.

    2008-01-01

    The most commonly cited descriptions of the behavioral characteristics of habituation come from two papers published almost 40 years ago (Thompson and Spencer, 1966; Groves and Thompson, 1970). In August 2007, the authors of this review, who study habituation in a wide range of species and paradigms, met to discuss their work on habituation and to revisit and refine the characteristics of habituation. This review offers a re-evaluation of the characteristics of habituation in light of these d...