2,085 research outputs found
Spread and establishment of Aedes albopictus in southern Switzerland between 2003 and 2014 : an analysis of oviposition data and weather conditions
The Asian tiger mosquito, Aedes albopictus, is a highly invasive mosquito species of public health importance. In the wake of its arrival in neighbouring Italy the authorities of the canton of Ticino in southern Switzerland initiated a surveillance programme in 2000 that is still on-going. Here we explored the unique data set, compiled from 2003 to 2014, to analyse the local dynamic of introduction and establishment of Ae. albopictus, its relative density in relation to precipitation and temperature, and its potential distribution at the passage from southern to northern Europe.; The presence of Ae. albopictus was recorded by ovitraps placed across Ticino. In addition to presence-absence, the relationship between relative egg densities and year, month, temperature and precipitation was analysed by a generalised linear mixed model.; Since its first detection in 2003 at Ticino's border with Italy Ae. albopictus has continuously spread north across the lower valleys, mainly along the trans-European motorway, E35. Detailed local analysis showed that industrial areas were colonised by the mosquito before residential areas and that, afterwards, the mosquito was more present in residential than in industrial areas. Ae. albopictus appeared sporadically and then became more present in the same places the following years, suggesting gradual establishment of locally reproducing populations that manage to overwinter. This trend continues as witnessed by both a growing area being infested and increasing egg counts in the ovitraps. There was a clear South-North gradient with more traps being repeatedly positive in the South and fewer eggs laid during periods of intensive precipitation. In the North, the mosquito appeared repeatedly through the years, but never managed to establish, probably because of unfavourable weather conditions and low road traffic.; Given the present results we assume that additional areas may still become infested. While the current study provides good estimates of relative egg densities and shows the local and regional dynamics of Ae. albopictus invasion, additional parameters ought to be measured to make an objective risk assessment for epidemic disease transmission. The likelihood of Ae. albopictus to further spread and increase in densities calls for continued surveillance
Measurement of the Cross Section Times Branching Ratio of Light Higgs Decays at CLIC
The investigation of the properties of a Higgs boson, especially a test of
the predicted linear dependence of the branching ratios on the mass of the
final state, is currently one of the most compelling arguments for building a
linear collider. We demonstrate that the large Higgs boson production cross
section at a 3 TeV CLIC machine allows for a precision measurement of the Higgs
branching ratios. The cross section times branching ratio of the decays H
\rightarrow b^{-}b, H \rightarrow cc^{-} and H \rightarrow {\mu}{\mu} can be
measured with a statistical uncertainty of 0.22%, 3.2% and 15%, respectively.Comment: LCWS 2011 Proceeding
Death comes suddenly to the unprepared: singing crickets, call fragmentation, and parasitoid flies
Male field crickets are subject to a delicate dilemma because their songs simultaneously attract mates and acoustic predators. It has been suggested that in response, crickets have modified various temporal song parameters to become less attractive to acoustic predators. We investigated whether crickets with chirping (versus trilling) song structures are less likely to attract acoustically orienting parasitoid flies. Experimentally, we evaluated the phonotactic quest of the parasitoid fly Ormia ochracea in response to broadcast cricket calls, presented both simultaneously (choice paradigm) and sequentially (no-choice paradigm). Flight trajectories were recorded in darkness using three-dimensional active infrared video tracking. The flies showed remarkable phonotactic accuracy by landing directly on the loudspeaker. The introduction of acoustic fragmentation that resembles calls of many chirping crickets altered the flies' phonotactic accuracy only slightly. Our results document differential attraction between trilling and chirping cricket songs and quantitatively demonstrate that chirping songs, if presented alone, do not impair the efficiency (temporal investment and landing accuracy) of the flies' phonotactic quest. This study shows that song fragmentation is no safeguard against acoustic parasitism. We conclude that, in general, a cricket may reduce predation only if its neighbors are acoustically more conspicuous, chiefly by amplitud
Divisão de trabalho durante o forrageamento de Acromyrmex crassispinus (Hymenoptera: Formicidae).
Behavior of Acromyrmex crassispinus in trail bifurcations and influence of ant flow on error rate of nestbound laden workers.
Resumo
Relaciones entre objetivos y métodos en el estudio de la indústria lítica
Tècniques innovadores, pràctiques concretes de la investigació... poden ésser compartides per diferents investigadors sense tenir en comú la mateixa ideologia (és a dir, amb objectius científics diferents), però és evident que no compartiran ni la lectura dels resultats ni et conjunt de la metodologia en la que s'insereixen aquestes tècniques. Aquesta metodologia i aquests objectius triats per cada investigador/a impliquen un vocabulari no gratuït. Aquest vocabulari és el que resulta més evident i per tant, acaba éssent la part més copiable, oblidant els que ho copien, o ignorant-ho, que mitjançant el vocabulari estan reconeixent com a propis uns objectius ja definits (i pels quals el vocabulari ha estat pensat). Aquest fet pot ésser el resultat d'oblidar que les paraules expresen/contenen un concepte. Aquest oblit inclueix la gènesi del concepte i, per tant, dins quin corrent teòric es situa. Si afegim a tot el dit anteriorment l'especialització, necessària però que contribueix a que els objectius generals es perdin un xic de vista, veurem que el vocabulari tècnic utilitzat acaba essent el que està de moda, sense saber a què respon i molt menys havent estat triat pel seu contingut. Nosaltres busquem la rendibilitat dels processos de treball implicats en la producció lítica perquè ens interessa no només descriure els processos de transformació i canvi econòmic-social de les societats caçadores, recol·lectores sinó especialment explicar aquest processos. Per això necessitem caracteritzar els grups en funció del grau de desenvolupament assolit en quant a la relació grup-medi i intergrupal, i la caracterització del sistema econòmic (amb l'Arqueologia no podem encara arribar al segment social) implica una avaluació de la rendibilitat dels processos de treball.New techniques, investigation practices... may be share for different researchers without have the same ideology (in other words, with differents scientific objectives), but is evident that they doesn't share the lecture of results neither the methodology into the different techniques are include. This methodology and this objectives chosen for every searcher involve a non innocent vocabulary. This vocabulary is the most evident thing, and the most borrowed part of this investigations, forgettng who it's coping, or ignoring it, that with the vocabulary are asumed as one 's own an objectives yet deffined (and for the vocabulary was thinked). This fact may be the result of forget that the words express/content concepts. This omission include the concept genesis and, therefore, the theoretical marc from it came. If we add to the exposed above the especialization, necessary but that may contribute to the miss of the main objectives, we can see that the technical vocabulary is at last used because is in fashion. without know his roots and without arguments for justify the choice ofthe different terms. We search the efficiency of the work processes that rapport with lithic production because our interest is not only for to describe but to explain the process of change among hunter-gatherers. For this we need to characterize humans groups trough the development level in the relations group-environment or intergroups, and the characterization of the economic system (with Archaeology we can't actually incide in the social segment) involve an evaluation of the efficiency of the work processes
Accumulation and toxic effects of chromium and zinc in Iris pseudacorus L
The aim of the present study was to examine the ability of I. pseudacorus L., an ornamental macrophyte of great potential for phytoremediation, to tolerate and accumulate Cr and Zn. Plants were grown in nutritive solution with ZnCl2 or CrCl3·6H2O at 0, 10, 50, 100, and 200 μg ml−1 for 5 weeks; all survived and continued growing. The accumulation of Cr and Zn increased with increasing supply in all plant tissues, to reach 59.97 mg Cr and 25.64 mg Zn in roots. Leaves retained a remarkable amount of Zn (14.2 mg). Growth inhibition reached 65% and 31% (dry weight) in response to Cr and Zn, respectively. The root:shoot dry matter partitioning (R/S) increased 80% at 100 μg ml−1 CrCl3. The most marked alterations in mineral content were in roots, where both metals decreased Al, Ca, Mg, Mn and S, and increased P concentration. No effect was noted on either leaf chlorophyll fluorescence kinetics (F v /F m and ΦPSII), or photosynthetic pigment content, signifying that the light phase of photosynthesis was not impaired. Carbon isotope composition (δ13C) was only slightly heavier, indicating that the reduction of carbon fixation was not the main cause for growth decrease. This was attributed to the restricted mineral uptake and to the increased demand of carbohydrates of damaged roots. Biomass allocation to rhizomes (Cr) or roots (Zn) contributes to heavy metal tolerance by limiting transpiration and increasing metal-storing tissues and the surface for water and cation uptake. This species is a good candidate for Cr rhizofiltration and Zn phytoextraction
Surveys on Propithecus verreauxi deckeni, a melanistic variant, and P. v. coronatus in north-west Madagascar
Propithecus verreauxi is currently divided into three or four subspecies. Decken's sifaka, P. v. deckeni, and the crowned sifaka, P. v. coronatus, are believed to be synonymous by some authors, while others regard them as separate subspecies. The results of a survey on an isolated melanistic population of Decken's sifaka, known from museum specimens collected in Ambararatabe, as well as the results of additional surveys carried out within the ranges of P. v. deckeni and P. v. coronatus are presented. A detailed description and photographs of the melanistic variant are provided. The data are employed to argue the case for recognition of the subspecific status of the endangered P. v. coronatus. The consistency of sightings of P. v. coronatus to the east of the river Mahavavy and to the west of the river Betsiboka, and sightings of P. v. deckeni to the west of the Mahavavy indicate clear separation of the two subspecies in the lower reaches of two rivers. Clarification of the status of the enigmatic museum specimens from Ambararatabe, representing a melanisticform rather than hybridization of P. v. deckeni and P. v. coronatus, lends further support to this argumen
Comparison of flag leaf and ear photosynthesis with biomass and grain yield of durum wheat under various water conditions and genotypes
Photosynthetic activity of cereals has traditionally been studied using leaves, thus neglecting the role of other organs such as ears. Here, we studied the effects of water status and genotypes on the photosynthetic activity of the flag leaf blade and the ear of durum wheat. The various parameters related to the photosynthetic activity were analysed in relation to the total above-ground plant biomass and grain yield at maturity. Four local varieties plus two cultivars adapted to the semiarid areas of South Morocco were grown in pots in a greenhouse. Five different water treatments were maintained from the beginning of stem elongation to maturity, when shoot biomass and grain yield were recorded. The net photosynthesis (A), stomatal conductance (gs) and transpiration (T) of the ear and the flag leaf were measured at anthesis. In both organs these factors decreased significantly with water deficit, whereas the A/T and A/gs ratios increased. The genotype effect was also significant for all traits studied. Whole-organ photosynthesis was much higher in the ear than in the flag leaf in well-watered conditions. As water stress developed, photosynthesis decreased less in the ear than in the flag leaf. Whole-ear photosynthesis correlated better than flag leaf photosynthesis with biomass and yield. Nevertheless, the relationships of the whole flag leaf with biomass and yield improved as the water stress became more severe, suggesting a progressive shift of yield from sink to source limitation. For all water regimes the ratios A/gs and A/T of the ear also showed a higher (negative) correlation with both biomass and yield than those of the flag leaf. The results indicate that the ear has a greater photosynthetic role than the flag leaf in determining grain yield, not only in drought but also in the absence of stress
Oviposition ecology and species composition of Aedes spp. and Aedes aegypti dynamics in variously urbanized settings in arbovirus foci in southeastern Côte d'Ivoire
Background
Aedes mosquito-transmitted outbreaks of dengue and yellow fever have been reported from rural and urban parts of Côte d’Ivoire. The present study aimed at assessing Aedes spp. oviposition ecology in variously urbanized settings within arbovirus foci in southeastern Côte d’Ivoire.
Methods
Aedes spp. eggs were sampled using a standard ovitrap method from January 2013 to April 2014 in different ecosystems of rural, suburban and urban areas. Emerged larvae were reared until the adult stage for species identification.
Results
Aedes spp. oviposition ecology significantly varied from rural-to-urban areas and according to the ecozones and the seasons. Species richness of Aedes spp. gradually decreased from rural (eight species) to suburban (three species) and urban (one species) areas. Conversely, emerged adult Aedes spp. mean numbers were higher in the urban (1.97 Aedes/ovitrap/week), followed by the suburban (1.44 Aedes/ovitrap/week) and rural (0.89 Aedes/ovitrap/week) areas. Aedes aegypti was the only species in the urban setting (100 %), and was also the predominant species in suburban (85.5 %) and rural (63.3 %) areas. The highest Ae. aegypti mean number was observed in the urban (1.97 Ae. aegypti/ovitrap/week), followed by the suburban (1.20 Ae. aegypti/ovitrap/week) and rural (0.57 Ae. aegypti/ovitrap/week) areas. Aedes africanus (9.4 %), Ae. dendrophilus (8.0 %), Ae. metallicus (1.3 %) in the rural, and Ae. vittatus (6.5 %) and Ae. metallicus (1.2 %) in the suburban areas each represented more than 1 % of the total Aedes fauna. In all areas, Aedes species richness and abundance were higher in the peridomestic zones and during the rainy season, with stronger variations in species richness in the rural and in abundance in the urban areas. Besides, the highest Culex quinquefasciatus abundance was found in the urban areas, while Eretmapodites chrysogaster was restricted to the rural areas.
Conclusions
Urbanization correlates with a substantially higher abundance in Aedes mosquitoes and a regression of the Aedes wild species towards a unique presence of Ae. aegypti in urban areas. Aedes wild species serve as bridge vectors of arboviruses in rural areas, while Ae. aegypti amplifies arbovirus transmission in urban areas. Our results have important ramifications for dengue and yellow fever vector control and surveillance strategies in arbovirus foci in southeastern Côte d’Ivoire
- …
