Home About us Contact
|
Home About us Contact | ||
|
|
||
Alternation
Kinds of Alternation Selected AbstractsCOEVOLUTIONARY ALTERNATION IN ANTAGONISTIC INTERACTIONSEVOLUTION, Issue 11 2006Scott L. Nuismer Abstract Coevolution between parasites and hosts or predators and prey often involves multiple species with similar kinds of defenses and counter-defenses. Classic examples include the interactions between phytophagous insects and their host plants, thick-shelled invertebrates and their shell-crushing predators, and ungulates and their predators. There are three major hypotheses for the nonequilibrium coevolutionary dynamics of these multispecific trophic interactions: escalation in traits, cycles in traits leading to fluctuating polymorphisms, and coevolutionary alternation. The conditions under which cycles and escalation are likely to occur have been well developed theoretically. In contrast, the conditions favoring coevolutionary alternation,evolutionary fluctuations in predator or prey preference driven by evolutionary shifts in relative levels of prey defense and vice versa,have yet to be identified. Using a set of quantitative coevolutionary models, we demonstrate that coevolutionary alternation can occur across a wide range of biologically plausible conditions. The result is often repeated, and potentially rapid, evolutionary shifts in patterns of specialization within networks of interacting species. [source] New drug combinations for the treatment of murine AIDS and macrophage protectionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2001A. Fraternale The failure of highly active antiretroviral therapies (HAART) is mainly due to the existence of latent infected reservoirs, such as macrophages and resting CD4+ T cells. In this paper, we report the results that we obtained in a murine model of AIDS by alternating the administration of the lympholitic drug 2-Fluoro-ara-AMP (Fludarabine) to eliminate the infected cells, with that of Azidothymidine (AZT) plus reduced glutathione (GSH) encapsulated in erythrocytes, to protect lymphocytes and macrophages not yet infected, respectively. Two groups of infected mice were treated as follows: one group was treated by alternating the administration of Fludarabine and AZT (treatment A), while the other group received the same treatment plus GSH-loaded erythrocytes given with AZT (treatment A + L,RBC). Fludarabine was administered intraperitoneally, AZT in the drinking water and GSH was encapsulated in erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. The results obtained show that GSH-loaded erythrocytes provide additive effects in all the parameters examined. Alternation of a lympholitic drug and antiretroviral drug is effective in reducing the progression of murine AIDS. Addition of a system to protect macrophages provides additive effects in almost all the parameters considered, confirming that combination therapies aimed at protecting different infectable cell compartments are better than treatments protecting mainly lymphocytes. [source] The Italian General Election of 13 May 2001: Democratic Alternation or False Step?GOVERNMENT AND OPPOSITION, Issue 4 2001Sergio Fabbrini First page of article [source] Optimal boundary control of cardiac alternansINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2009Stevan Dubljevic Abstract Alternation of normal electrical activity in the myocardium is believed to be linked to the onset of life-threatening ventricular arrhythmias and sudden cardiac death. In this paper, a spatially uniform unstable steady state of small amplitude of alternans described by parabolic partial differential equations (PDEs) is stabilized by boundary optimal control methods. A finite dimensional linear quadratic regulator (LQR) is utilized in both a full-state-feedback control structure and in a compensator design with the Luenberger observer, and it achieves global stabilization in a finite size tissue cable length. The ability to realize such control algorithm is analyzed based on the structure of the amplitude of alternans equation and the control methodology applied. Copyright © 2008 John Wiley & Sons, Ltd. [source] Alternation of Chemoselective Control in Stille,Heck and Heck,Stille Reaction SequencesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009Kye-Simeon Masters The communication by Kye-Simeon Masters and Bernard L. Flynn in Issue 4, 2009, pp. 530,536 (DOI: 10.1002/adsc.200800678), should have appeared in this issue dedicated to Professor Armin de Meijere. It was published in Issue 4, 2009, by mistake. On the title page, below the received and publication dates, the following dedication should appear: "Dedicated to Professor Armin de Meijere on the occasion of his 70th birthday." The editorial office apologizes for this mistake. [source] Alternation of Chemoselective Control in Stille,Heck and Heck,Stille Reaction SequencesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Kye-Simeon Masters Abstract Sequential and one-pot Stille,Heck and Heck,Stille reaction processes have been invoked to give divergent access to polycyclic ring systems. Both reaction conditions and substrate structure are important in determining the nature of the reaction products formed. The Heck,Stille reactions have involved a reversal of the usual Heck regioselectivity and both cine- and ipso- substitutions have been observed in the Stille reaction. [source] Long RP Tachycardia with RR AlternationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2000TOSHIO ITO No abstract is available for this article. [source] Alternation of Estrogen Receptor and Progesterone Receptor Expression in Primary Breast Cancer Patients Treated with Neoadjuvant ChemotherapyTHE BREAST JOURNAL, Issue 4 2010Dai Kitagawa MD No abstract is available for this article. [source] Role of the neuropeptide CCAP in Drosophila cardiac functionDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2005Davide Dulcis Abstract The heartbeat of adult Drosophila melanogaster displays two cardiac phases, the anterograde and retrograde beat, which occur in cyclic alternation. Previous work demonstrated that the abdominal heart becomes segmentally innervated during metamorphosis by peripheral neurons that express crustacean cardioactive peptide (CCAP). CCAP has a cardioacceleratory effect when it is applied in vitro. The role of CCAP in adult cardiac function was studied in intact adult flies using targeted cell ablation and RNA interference (RNAi). Optical detection of heart activity showed that targeted ablation of CCAP neurons selectively altered the anterograde beat, without apparently altering the cyclic cardiac reversal. Normal development of the abdominal heart and of the remainder of cardiac innervation in flies lacking CCAP neurons was confirmed by immunocytochemistry. Thus, in addition to its important role in ecdysis behavior (the behavior used by insects to shed the remains of the old cuticle at the end of the molt), CCAP may control the level of activity of the anterograde cardiac pacemaker in the adult fly. Expression of double stranded CCAP RNA in the CCAP neurons (targeted CCAP RNAi) caused a significant reduction in CCAP expression. However, this reduction was not sufficient to compromise CCAP's function in ecdysis behavior and heartbeat regulation. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 [source] Studies on the morphometry of the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae)ENTOMOLOGICAL RESEARCH, Issue 2 2007Potshangbam Bijaya DEVI Abstract Aphids are one of the most important groups of phytophagous insects because of their polyphenism, host alternation, heteroecious behavior and reproductive habits. Laboratory culture of the aphid Myzus persicae on the host plant Brassica pekinensis Hubner was maintained seasonally for biometrical studies. The metric analysis revealed gradual developmental changes from the first instar nymph to the adult stage in size, shape, and a number of characters. The transitional changes were sufficiently distinct to allow differentiation of each of the life stages irrespective of the season. A key to the nymphal stages of the pest is provided. [source] Effects of parasitoids on a mycophagous drosophilid community in northern Japan and an evaluation of the disproportionate parasitism hypothesisENTOMOLOGICAL SCIENCE, Issue 1 2006Hiroshi YOROZUYA Abstract In a host,parasitoid system comprising mycophagous drosophilids and their parasitoids, the drosophilid and parasitoid species assemblages, host use, and the prevalence of parasitism were assessed, and the "disproportionate parasitism hypothesis" was examined with consideration given to yearly variations. The mycophagous drosophilids, their fungal food resources and parasitoids were studied by carrying out an intensive census throughout the activity seasons of 4 years (2000,2003) in Hokkaido, northern Japan. Five hymenopterous parasitoid species, four braconids and one eucoilid, were found. Parasitoids of mycophagous drosophilids are reported for the first time from Asia. Most parasitism (99.2%) was by braconids, in contrast to the dominance of eucoilids in Europe. Parasitism was restricted to the summer, and the rate was high from early July to early August every year. There was considerable yearly variation in the composition of abundant fungus, drosophilid and parasitoid species, especially between 2000 and 2001. The alternation of dominant host species was coupled with the alternation of dominant parasitoid species that differed in host use. Despite the yearly variation in the system, the most dominant host species suffered disproportionately heavy parasitism by the correspondingly dominant parasitoid species every year. The parasitism rate was positively correlated with the relative host abundance. This thus indicates that the disproportionate parasitism mechanism may operate, via which species coexistence is promoted by a higher rate of parasitism of the dominant species. [source] Tetracyanoquinodimethanido Derivatives of (Terpyridine)- and (Phenanthroline)metal Complexes , Structural and Magnetic Studies of Radical-Ion SaltsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2005Cristina Alonso Abstract Several derivatives of formulae [M(terpy)2](TCNQ)2 or [M(terpy)2](TCNQ)3 (M = Ni, Cu, Zn; terpy = 2,2,:6,,2"-terpyridine; TCNQ= 7,7,8,8-tetracyanoquinodimethane) and [M(phen)3](TCNQ)2 or [M(phen)3](TCNQ)4 (M = Fe, Ni; phen = 1,10-phenanthroline) have been obtained. The crystal structures of [M(terpy)2](TCNQ)2 (M = Ni, Cu) show that the metal is surrounded by the terpyridine nitrogen atoms in a closed octahedral environment and the TCNQ anions are dimerised by , overlap. The cationic [M(terpy)2]2+ and the anionic [TCNQ]22, groups alternate in the crystal. For the derivatives with three TCNQ groups, the existence of a stack of trimeric [TCNQ]32, ions having electronic delocalisation is proposed. The compound [Fe(phen)3](TCNQ)2, which shows a strong interaction between TCNQ anions, led to the formation of a , bond in the diamagnetic species [TCNQ,TCNQ], while the nickel analogue is expected to have a localised structure formed by alternation of cationic metal complexes and dimeric [TCNQ]22, anions similar to those observed in the analogous terpy derivatives. The derivatives having four TCNQ groups also show electronic delocalisation and a 1D stack based on the magnetic data is proposed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Odor vapor pressure and quality modulate local field potential oscillatory patterns in the olfactory bulb of the anesthetized ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2008Tristan Cenier Abstract A central question in chemical senses is the way that odorant molecules are represented in the brain. To date, many studies, when taken together, suggest that structural features of the molecules are represented through a spatio-temporal pattern of activation in the olfactory bulb (OB), in both glomerular and mitral cell layers. Mitral/tufted cells interact with a large population of inhibitory interneurons resulting in a temporal patterning of bulbar local field potential (LFP) activity. We investigated the possibility that molecular features could determine the temporal pattern of LFP oscillatory activity in the OB. For this purpose, we recorded the LFPs in the OB of urethane-anesthetized, freely breathing rats in response to series of aliphatic odorants varying subtly in carbon-chain length or functional group. In concordance with our previous reports, we found that odors evoked oscillatory activity in the LFP signal in both the beta and gamma frequency bands. Analysis of LFP oscillations revealed that, although molecular features have almost no influence on the intrinsic characteristics of LFP oscillations, they influence the temporal patterning of bulbar oscillations. Alcohol family odors rarely evoke gamma oscillations, whereas ester family odors rather induce oscillatory patterns showing beta/gamma alternation. Moreover, for molecules with the same functional group, the probability of gamma occurrence is correlated to the vapor pressure of the odor. The significance of the relation between odorant features and oscillatory regimes along with their functional relevance are discussed. [source] Genetic ablation of the mammillary bodies in the Foxb1 mutant mouse leads to selective deficit of spatial working memoryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Konstantin Radyushkin Abstract Mammillary bodies and the mammillothalamic tract are parts of a classic neural circuitry that has been implicated in severe memory disturbances accompanying Korsakoff's syndrome. However, the specific role of mammillary bodies in memory functions remains controversial, often being considered as just an extension of the hippocampal memory system. To study this issue we used mutant mice with a targeted mutation in the transcription factor gene Foxb1. These mice suffer perinatal degeneration of the medial and most of the lateral mammillary nuclei, as well as of the mammillothalamic bundle. Foxb1 mutant mice showed no deficits in such hippocampal-dependent tasks as contextual fear conditioning and social transmission of food preference. They were also not impaired in the spatial reference memory test in the radial arm maze. However, Foxb1 mutants showed deficits in the task for spatial navigation within the Barnes maze. Furthermore, they showed impairments in spatial working memory tasks such as the spontaneous alternation and the working memory test in the radial arm maze. Thus, our behavioural analysis of Foxb1 mutants suggests that the medial mammillary nuclei and mammillothalamic tract play a role in a specific subset of spatial tasks, which require combined use of both spatial and working memory functions. Therefore, the mammillary bodies and the mammillothalamic tract may form an important route through which the working memory circuitry receives spatial information from the hippocampus. [source] COEVOLUTIONARY ALTERNATION IN ANTAGONISTIC INTERACTIONSEVOLUTION, Issue 11 2006Scott L. Nuismer Abstract Coevolution between parasites and hosts or predators and prey often involves multiple species with similar kinds of defenses and counter-defenses. Classic examples include the interactions between phytophagous insects and their host plants, thick-shelled invertebrates and their shell-crushing predators, and ungulates and their predators. There are three major hypotheses for the nonequilibrium coevolutionary dynamics of these multispecific trophic interactions: escalation in traits, cycles in traits leading to fluctuating polymorphisms, and coevolutionary alternation. The conditions under which cycles and escalation are likely to occur have been well developed theoretically. In contrast, the conditions favoring coevolutionary alternation,evolutionary fluctuations in predator or prey preference driven by evolutionary shifts in relative levels of prey defense and vice versa,have yet to be identified. Using a set of quantitative coevolutionary models, we demonstrate that coevolutionary alternation can occur across a wide range of biologically plausible conditions. The result is often repeated, and potentially rapid, evolutionary shifts in patterns of specialization within networks of interacting species. [source] ECOLOGICAL BISTABILITY AND EVOLUTIONARY REVERSALS UNDER ASYMMETRICAL COMPETITIONEVOLUTION, Issue 6 2002Fabio Dercole Abstract How does the process of life-history evolution interplay with population dynamics? Almost all models that have addressed this question assume that any combination of phenotypic traits uniquely determine the ecological population state. Here we show that if multiple ecological equilibria can exist, the evolution of a trait that relates to competitive performance can undergo adaptive reversals that drive cyclic alternation between population equilibria. The occurrence of evolutionary reversals requires neither environmentally driven changes in selective forces nor the coevolution of interactions with other species. The mechanism inducing evolutionary reversals is twofold. First, there exist phenotypes near which mutants can invade and yet fail to become fixed; although these mutants are eventually eliminated, their transitory growth causes the resident population to switch to an alternative ecological equilibrium. Second, asymmetrical competition causes the direction of selection to revert between high and low density. When ecological conditions for evolutionary reversals are not satisfied, the population evolves toward a steady state of either low or high abundance, depending on the degree of competitive asymmetry and environmental parameters. A sharp evolutionary transition between evolutionary stasis and evolutionary reversals and cycling can occur in response to a smooth change in ecological parameters, and this may have implications for our understanding of size-abundance patterns. [source] Triassic metasedimentary successions across the boundary between the southern Apennines and the Calabrian Arc (northern Calabria, Italy)GEOLOGICAL JOURNAL, Issue 2 2005A. Iannace Abstract The boundary area between the Apenninic fold-and-thrust belt and the crystalline Calabrian Arc, located around Sangineto in northern Calabria, has been investigated. New geological mapping in the Sant'Agata area has been performed on the Triassic successions traditionally attributed to the metasedimentary San Donato Unit. This, coupled with a reappraisal of the stratigraphy and tectonics of coeval successions present more to the south in the Cetraro Unit, results in a new reconstruction of the Triassic evolution of all the metasedimentary successions found in the region. Four informal stratigraphic units have been distinguished in the S. Agata area. The lowest one (Unit A) consists of well-bedded metalimestones and bioturbated marly limestones that correlate with Ladinian,Carnian carbonates in nearby areas. A second unit (Unit B), never recognized before, contains a complex alternation of dolomites, phyllites and some meta-arenites containing several beds of Cavernoso facies, attributed to the Carnian. They grade upward to platform and platform-margin dolomites of Norian,Rhaetian age (Unit C) that in turn are replaced upward and laterally by a fourth unit (Unit D) consisting of well-bedded, dark dolomites and metalimestones with marly interlayers locally found as resedimented large blocks in slope conglomerates. Unit D correlates with Rhaetian,Liassic beds in nearby areas. Several pieces of evidence of post-metamorphic contractional tectonics, with 140°N and 30°N trends, are found together with evidence of SW-directed extension. The siliciclastic Carnian beds of Unit B are correlated with the phyllites of Cetraro, formerly believed to be Middle Triassic; moreover, it is suggested that in the Cetraro area Unit C is almost totally replaced by Unit D. This demonstrates that the former distinction between the two tectonic units in the whole area has to be discarded. We have made a general palaeoenvironmental reconstruction which progresses laterally, during Ladinian,Carnian times, from (i) a coastal, mixed siliciclastic,carbonate,evaporitic area at Cetraro to (ii) a transitional carbonate shelf where siliciclastic input was only episodic, and finally to (iii) a bioconstructed margin which was later replaced by a steepened margin created by tectonic instability. Starting from the Norian, subsidence shifted toward the former coastal area where an intraplatform, restricted basin developed. The proposed stratigraphy corresponds closely to the Alpujarride units of the Betic Cordillera, Spain. Moreover, it is shown that strong affinities also exist, in terms of the structural framework, with the metamorphic units of Tuscany and Liguria. Copyright © 2005 John Wiley & Sons, Ltd. [source] Lagoon,tidal flat sedimentation in an epeiric sea: Proterozoic Bhander Group, Son Valley, IndiaGEOLOGICAL JOURNAL, Issue 2 2001Chandan Chakraborty Abstract The Bhander Group, the uppermost stratigraphic unit of the Proterozoic Vindhyan Supergroup in Son Valley, exhibits in its upper part a 550,m thick, muddy siliciclastic succession characterized by features indicative of deposition in a wave-affected coastal, lagoon,tidal flat environment suffering repeated submergence and emergence. The basic architecture of the deposit is alternation of centimetre- to decimetre-thick sheet-like interbeds of coarser clastics (mainly sandstone) and decimetre-thick mudstones. The coarser interlayers are dominated by a variety of ripple-formed laminations. The preserved ripple forms on bed-top surfaces and their internal lamination style suggest both oscillatory and combined flows for their formation. Interference, superimposed, ladder-back and flat-topped ripples are also common. Synsedimentary cracks, wrinkle marks, features resembling rain prints and adhesion structures occur in profusion on bed-top surfaces. Salt pseudomorphs are also present at the bases of beds. The mudstone intervals represent suspension settlement and show partings with interfaces characterized by synsedimentary cracks. It is inferred that the sediments were deposited on a coastal plain characterized by a peritidal (supratidal,intertidal) flat and evaporative lagoon suffering repeated submergence and emergence due to storm-induced coastal setup and setdown in addition to tidal fluctuations. The 550,m thick coastal flat succession is surprisingly devoid of any barrier bar deposits and also lacks shoreface and shelfal strata. The large areal extent of the coastal flat succession (c. 100,000,km2) and its great thickness indicate an extremely low-gradient epeiric basin characterized by an extensive coastal flat sheltered from the deeper marine domain. It is inferred that the Bhander coastal flat was protected from the open sea by the Bundelkhand basement arch to the north of the Vindhyan basin, instead of barrier bars. Such a setting favoured accumulation of a high proportion of terrigenous mud in the coastal plain, in contrast to many described examples from the Proterozoic. Copyright © 2001 John Wiley & Sons, Ltd. [source] Still the Anomalous Democracy?GOVERNMENT AND OPPOSITION, Issue 1 2009Institutions in Italy, Politics Until the early 1990s, the Italian political system was regarded as anomalous among advanced democracies because of its failure to achieve alternation in government. Since then, that problem has been overcome, but Italy has been popularly viewed as continuing to be different to other democracies because it is ,in transition' between regimes. However, this position itself is becoming increasingly difficult to sustain because of the length of time of this so-called transition. Rather than focus on what is rather an abstract debate, it may be more fruitful to analyse what, in substance, is distinctive about Italian politics in this period: the manner in which a debate over fundamental institutional (including electoral) reform has become entangled in day-to-day politics. This can best be exemplified through an analysis of two key electoral consultations held in 2006: the national elections and the referendum on radically revising the Italian Constitution. [source] Groundwater fluctuations and footslope ferricrete soils in the humid tropical zone of southern CameroonHYDROLOGICAL PROCESSES, Issue 16 2005Emile Temgoua Abstract This paper discusses the relationship between the differentiation of ferruginous accumulations and the variable water saturation of footslope soil patterns. An analysis of the slope morphology of a typical hill in the forest zone of southern Cameroon and a seasonal survey of the levels of groundwaters, springs and rivers were considered in relation to the petrology of different soil patterns. The study site is a tabular hillock whose slopes present a progressive development from steep to gentle slopes. The variable residence time of water within the soil, creating an alternation of reducing and oxidizing conditions, affects soil chemistry, structure and lateral extension of the soil patterns. The ferruginous soil patterns, being formed on the footslopes, gradually increase in extent with decreasing slope angle and the relative rise of the groundwater level. The steep footslopes, where groundwater has a shorter residence time, show a soft mottled clay pattern, restricted to the bottom part of the slope. The moderate footslopes exhibit a deep permanent and a temporary perched groundwater table. The latter, with its regular capillary fringe, contributes to more reducing conditions within isolated domains in the soil patterns, and thus to the alternation with oxidizing conditions, generating a continuous hard soil pattern (massive carapace). The more gently dipping footslopes exhibit groundwater levels near the surface and also a significant amplitude of groundwater fluctuation. Iron, previously accumulated in moderate footslope patterns, is reduced, remobilized, and leached. The soil patterns formed develop into a variegated carapace, more extended along the slope, containing less iron, but nevertheless more hardened, due to the important fluctuations of the groundwater table. These patterns are limited to the zone of groundwater fluctuation and deteriorate as the water fluctuation zone recedes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Spatiotemporal Regularity and Interevent Contingencies as Information for Infants' Visual ExpectationsINFANCY, Issue 3 2002Naomi Wentworth This study examined infants' use of picture-location contingencies and spatiotemporal regularity in forming visual expectations. Ninety-six 3-month-olds watched an event sequence in which pictures appeared at 3 locations, either in regular left-center-right alternation or in a random center-side pattern. For half of the infants, the content of the central picture was predictive of the location of the upcoming peripheral event. Analyses of anticipations and interpicture fixation shifts revealed that both spatiotemporal regularity and consistent interevent contingencies fostered increased anticipation of peripheral pictures. The type of spatiotemporal sequence that infants observed also differentially biased their responses to test trials that followed the picture sequence: Infants who experienced regular alternation sequences continued the side-to-side pattern during the 2-choice test trials, whereas infants who experienced irregular sequences looked back to the location of the previous picture. Stable interevent contingencies, in contrast, did not bias infants' responses toward the contingent side during the choice test trials. [source] A discourse-analytic approach to the use of English in Cypriot Greek conversationsINTERNATIONAL JOURNAL OF APPLIED LINGUISTICS, Issue 2 2001Dionysis Goutsos The use of English in Cypriot Greek has been a highly contested issue, involving much speculation and prescription but, as yet, little analysis of actual data. This study is a preliminary exploration of the issue, focusing on extensive data from informal conversations between members of a Limassol family. The analysis suggests that instances of language alternation can be accounted for in terms of discourse analytic categories such as the distinction between local and global phenomena and the tri-partite scheme of ideational, interpersonal and sequential functions. The presence of English in Cypriot Greek conversations covers a wide range, from local borrowing to stereotypical sequential or more complex interpersonal and sequential phenomena, and cannot be effectively separated from the role that language alternation plays in speci ?c textual and contextual settings. The discussion suggests that a discourse analytic approach is an indispensable means of studying language alternation phenomena. [source] Observational relationships between summer and winter monsoons over East Asia.INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2005Part II: results Abstract Using the framework presented in part I of this study, three possible summer-to-winter monsoon and four possible winter-to-summer monsoon relationships are identified. A generalized relationship between summer and winter monsoons is virtually non-existent, and some of the possible relationships are in fact tied to the influence of the El Niño,southern oscillation (ENSO). Indeed, relationships between summer and winter monsoons are specific in terms of both the winter monsoon strength and the ENSO conditions. It is found that the strength of winter monsoon is unlikely to be an important forcing regarding the possible winter-to-summer monsoon relationships, since the summer monsoon is unlikely to be weak following a non-ENSO-coupled winter monsoon, regardless of the winter monsoon strength. On the other hand, possible summer-to-winter relationships are noted only when the summer monsoon is not weak, regardless of the ENSO condition. An alternation or opposite tendency in the summer monsoon strength is noted between the onset year (tends to be unlikely weak) and the following year (tends to be unlikely strong) of an El Niño. Therefore, certain possible relationships between summer and winter monsoons are obvious when the winter monsoon tends to be weaker during the mature phase of an El Niño. For a La Niña, the signature in the summer monsoon strength is less clear, as indicated from the assessment of summer monsoon indices. Nevertheless, when the winter monsoon tends to be strong when coupled with a La Niña, the following summer monsoon also tends to be weaker. A biennial alternation of the summer and winter monsoons is noted, i.e. that a stronger summer monsoon precedes a weaker winter monsoon and a weaker winter monsoon is followed by a stronger summer monsoon. This biennial alternation is associated with a transition of ENSO warm phase to ENSO cold phase, representing the biennial signal in the interannual variability of the monsoons as well as in ENSO. Concurrent with this biennial alternation is an evident variation in the subtropical-high strength. It appears that the commonly recognized tropical biennial oscillation (TBO) is not tied to the biennial signal in the interannual variability of the East Asian monsoons, because the TBO is constituted by a strong (weak) summer monsoon followed by strong (weak) winter monsoon process. Furthermore, it is suggested that a complete biennial oscillation in the interannual variability of the monsoons is not observed because of the breakdown of a cycle (or oscillation) in the summer monsoon following a La Niña onset. Copyright © 2005 Royal Meteorological Society. [source] Climate dynamics of atmosphere and ocean in the equatorial zone: a synthesisINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2004Stefan Hastenrath Abstract A synopsis is offered of circulation mechanisms in the oceanic regions of the equatorial zone. Over the eastern Atlantic and Pacific, and especially in boreal summer, cross-equatorial flow from the Southern Hemisphere is strong and induces a tongue of cold surface waters, centred to the south of the equator. Upon crossing the equator in these sectors, owing to the Coriolis effect and a kinetic energy imbalance, the airstream speeds up and divergence develops, producing the Intertropical Divergence Zone (ITDZ). Once these processes result in the wind recurving from southeasterly to southwesterly, the flow slows down and becomes convergent, manifest in the Intertropical Convergence Zone, with a maximum to the south of the wind confluence. By contrast, over the western Atlantic and central Pacific and especially in boreal winter, winds in the equatorial band are predominantly from the east, upper-ocean Ekman transport is directed away from the equator, and the upwelling and cold tongue are centred on the equator. Cross-equatorial flow is insufficient to produce recurvature, the ITDZ is narrower and weaker, the divergence maximum is at the equator rather than in low northern latitudes, and the convergence maximum straddles the wind confluence. Over the Indian Ocean, the wind field is dominated by the alternation between the predominantly meridional flow of the winter and summer monsoons. Equatorial westerlies are limited to the short monsoon transition seasons. Essential for their origin is an eastward pressure gradient along the equator and weak southern trade winds, allowing recurvature somewhat south of the equator. Because the zonal pressure gradient is strongest in boreal summer and the southern trade winds are weakest in austral summer, the equatorial westerlies peak in spring and autumn. The boreal autumn equatorial westerlies are the surface manifestation of a powerful zonal,vertical circulation cell along the Indian Ocean equator. Equatorial zonal,vertical circulation cells require well-developed zonal flow in the lower troposphere along the equator and, therefore, appear confined to the oceanic longitudes and certain seasons. Thus, they are found over the Atlantic only in boreal winter and over the Indian Ocean only in boreal autumn, whereas over the Pacific they prevail all year round. Copyright © 2004 Royal Meteorological Society [source] Theoretical study on the second-order nonlinear optical properties of nonconjugated D-,-A chromophoresINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 7 2009Guochun Yang Abstract Density functional theory calculations have been carried out on nonconjugated D-,-A chromophores to investigate the different electron donors and conjugated bridges effects on the molecular nonlinear optical response. The results show that the large second-order polarizability values can be achieved through careful combination of available electron donors, conjugated bridges for our studied nonconjugated D-,-A chromophores. The calculations also provide a clear explanation for the second-order polarizability changes from the standpoint of transition energies, oscillator strengths, electron density difference, and bond length alternation. Solvent effect has great influence on the second-order polarizability and electronic absorption spectrum. It is hoped that the results presented in this article will give some hints to the interrelated studies. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Theoretical study of CnCl, CnCl+, CnCl, (n=1,7) clustersINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2001Antonio Largo Abstract A theoretical study of CnCl, CnCl+, and CnCl, (n=1,7) clusters has been carried out. Predictions for their electronic structures, dipole moments, and vibrational frequencies have been made at the B3LYP/6-311G(d) level. According to our calculations the lowest-lying geometry of all these species (with the only exception of neutral C3Cl) is predicted to be either a linear or quasi-linear structure with chlorine located at the end of the carbon chain. CnCl clusters all have doublet ground states, whereas the anionic clusters, with the only exception of CCl,, all have singlet ground states. For CnCl+ species, n -even clusters have triplet ground states whereas n -odd ones have singlet ground states. An even,odd parity effect (n -even clusters more stable than n -odd ones) is found for both the neutral and anionic species, whereas in the case of the cations the alternation in stability is reversed. The ionization potential (IP) and electron affinity (EA) also exhibit regular variations with the size of the cluster, with n -even clusters having both higher IP and EA than n -odd ones. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 127,135, 2001 [source] Tectono-metamorphic history of the Tacagua ophiolitic unit (Cordillera de la Costa, northern Venezuela): Insights in the evolution of the southern margin of the Caribbean PlateISLAND ARC, Issue 1 2007Alessandro Ellero Abstract The southern margin of the Caribbean Plate is well exposed in the Cordillera de la Costa of northern Venezuela, where amalgamated terranes consisting of continental and oceanic units occur. In the Cordillera de la Costa, metamorphosed oceanic units crop out along the coast near Caracas. Among them, the Tacagua unit is characterized by metaserpentinites and metabasites showing mid-oceanic ridge basalt geochemical affinity. These lithologies, representative of a disrupted ophiolite sequence, are associated with metasediments consisting of calcschists alternating with pelitic and psammitic schists, whose protoliths were probably represented by deep-sea hemipelagic and turbiditic deposits. In the Tacagua unit, a polyphase deformation history has been reconstructed, consisting of four folding phases from D1 to D4. Geological setting suggests an involvement of the Tacagua unit in the processes connected with a subduction zone. The following deformations (from D2 to D4) observed in the field might be related to the exhumation history of the Tacagua unit. The late deformation history consists of an alternation of deformation phases characterized by displacement parallel (D2 and D4 phases) and normal (D3 phase) to plate boundary between the Caribbean and South America Plates. All lines of geological evidence suggest that the whole evolution of the Tacagua unit was acquired in a setting dominated by oblique convergence, in which alternation of strike-slip and pure compressional or pure extensional tectonics occurred through time. [source] Characterization of micro-organisms isolated from dairy industry after cleaning and fogging disinfection with alkyl amine and peracetic acidJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2005E. Bore Abstract Aims:, To characterize micro-organisms isolated from Norwegian dairy production plants after cleaning and fogging disinfection with alkyl amine/peracetic acid and to indicate reasons for survival. Methods and Results:, Microbial samples were collected from five dairy plants after cleaning and fogging disinfection. Isolates from two of these production plants, which used fogging with alkylamino acetate (plant A), and peracetic acid (plant B), were chosen for further characterization. The sequence of the 16S ribosomal DNA, fatty acid analysis and biochemical characteristics were used to identify isolates. Three isolates identified as Rhodococcus erythropolis, Methylobacterium rhodesianum and Rhodotorula mucilaginosa were isolated from plant A and one Sphingomonas sp. and two M. extorquens from plant B. Different patterns of resistance to seven disinfectants in a bactericidal suspension test and variable degree of attachment to stainless steel were found. The strains with higher disinfectant resistance showed lower degree of attachment than susceptible strains. Conclusions:, The study identifies and characterizes micro-organisms present after cleaning and fogging disinfection. Both surface attachment and resistance were shown as possible reasons for the presence of the isolates after cleaning and disinfection. Significance and Impact of the Study:, These results contribute to the awareness of disinfectant resistance as well as attachment as mechanisms of survival in dairy industry. It also strengthens the argument of frequent alternation of disinfectants in the food processing industry to avoid the establishment of resistant house strains. [source] Developmental insights into experience-based decision makingJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 1 2010Tim Rakow Abstract In three experiments involving children and adults (N,=,324), option payoffs for sure versus risky choices were either described or experienced via observation of 20 outcomes. Choices revealed a description-experience gap for payoffs with rare events, implying greater impact of small probabilities (,.2) for described than for experienced choices. The size of this effect was independent of participant age. Therefore, the role of cognitive limitations in the description-experience distinction remains unclear, as the age groups would have differed in cognitive capacity. Age-related differences in ,sampling style' in decisions from experience were observed. Pre-choice data acquisition changed markedly with age: From frequent alternation between options towards separate systematic exploration of options with increasing age. A fourth experiment, that manipulated sampling style, failed to demonstrate its link to other age-related features of choice (e.g. risk preferences). Our studies illustrate the value of developmental research for testing theoretical claims and revealing novel phenomena in decision research. Copyright © 2009 John Wiley & Sons, Ltd. [source] Being an intensive care nurse related to questions of withholding or withdrawing curative treatmentJOURNAL OF CLINICAL NURSING, Issue 1 2007Reidun Hov MNSc Aims and objectives., The aim of the study was to acquire a deeper understanding of what it is to be an intensive care nurse in situations related to questions of withholding or withdrawing curative treatment. Background., Nurses in intensive care units regularly face critically ill patients. Some patients do not benefit from the treatment and die after days or months of apparent pain and suffering. A general trend is that withdrawal of treatment in intensive care units is increasing. Physicians are responsible for decisions concerning medical treatment, but as nurses must carry out physicians' decisions, they are involved in the consequences. Design and methods., The research design was qualitative, based on interpretative phenomenology. The study was carried out at an adult intensive care unit in Norway. Data were collected by group interviews inspired by focus group methodology. Fourteen female intensive care nurses participated, divided into two groups. Colaizzi's model was used in the process of analysis. Results., The analysis revealed four main themes which captured the nurses' experiences: loneliness in responsibility, alternation between optimism and pessimism, uncertainty , a constant shadow and professional pride despite little formal influence. The essence of being an intensive care nurse in the care of patients when questions were raised concerning curative treatment or not, was understood as ,being a critical interpreter and a dedicated helper.' Conclusions., The findings underpin the important role of intensive care nurses in providing care and treatment to patients related to questions of withholding or withdrawing curative treatment. Relevance to clinical practice., The findings also show the need for physicians, managers and intensive care nurses themselves to recognize the burdens intensive care nurses carry and to appreciate their knowledge as an important contribution in decision making. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||