804 resultados para Todd, Doug
Resumo:
A global climate model experiment is performed to evaluate the effect of irrigation on temperatures in several major irrigated regions of the world. The Community Atmosphere Model, version 3.3, was modified to represent irrigation for the fraction of each grid cell equipped for irrigation according to datasets from the Food and Agriculture Organization. Results indicate substantial regional differences in the magnitude of irrigation-induced cooling, which are attributed to three primary factors: differences in extent of the irrigated area, differences in the simulated soil moisture for the control simulation (without irrigation), and the nature of cloud response to irrigation. The last factor appeared especially important for the dry season in India, although further analysis with other models and observations are needed to verify this feedback. Comparison with observed temperatures revealed substantially lower biases in several regions for the simulation with irrigation than for the control, suggesting that the lack of irrigation may be an important component of temperature bias in this model or that irrigation compensates for other biases. The results of this study should help to translate the results from past regional efforts, which have largely focused on the United States, to regions in the developing world that in many cases continue to experience significant expansion of irrigated land.
Resumo:
Valinomycin, an ionophore of considerable interest for its ion selectivity, and its K+, Mg2+, Ba2+, and Ca2+ complexes were studied by Raman spectroscopy. Each complex has a characteristic spectrum which differs from that of uncomplexed valinomycin, suggesting several distinct structures for each of the metal-valinomycin complexes. The biologically active potassium complex shows the most significant changes in its spectrum, especially in the intensity of the symmetric C---H stretching vibration of CH3 and the convergence of the two ester carbonyl stretching vibration bands into one complex formation. These results are due to the unique orientation of the ester carbonyl groups toward the caged potassium ion and the resulting more free rotation of isopropyl side chains. The divalent cation-valinomycin complexes examined showed spectra which differed in each case uniquely from both valinomycin and its complex with potassium.
Resumo:
Males of some species included in the Bactrocera dorsalis complex are strongly attracted to methyl eugenol (ME) (1,2-dimethoxy-4-(2-propenyl) benzene), a natural compound occurring in a variety of plant species. ME feeding of males of the B. dorsalis complex is known to enhance their mating competitiveness. Within B. dorsalis, recent studies show that Asian and African populations of B. dorsalis are sexually compatible, while populations of B. dorsalis and Bactrocera carambolae are relatively incompatible. The objectives of this study were to examine whether ME feeding by males affects mating compatibility between Asian and African populations of B. dorsalis and ME feeding reduces male mating incompatibility between B. dorsalis (Asian population) and B. carambolae. The data confirmed that Asian and African populations of B. dorsalis are sexually compatible for mating and showed that ME feeding only increased the number of matings. Though ME feeding also increased the number of matings of B. dorsalis (Asian population) and B. carambolae males but the sexual incompatibility between both species was not reduced by treatment with ME. These results conform to the efforts resolving the biological species limits among B. dorsalis complex and have implications for fruit fly control programs in fields and horticultural trade.
Resumo:
Movement of tephritid flies underpins their survival, reproduction, and ability to establish in new areas and is thus of importance when designing effective management strategies. Much of the knowledge currently available on tephritid movement throughout landscapes comes from the use of direct or indirect methods that rely on the trapping of individuals. Here, we review published experimental designs and methods from mark-release-recapture (MRR) studies, as well as other methods, that have been used to estimate movement of the four major tephritid pest genera (Bactrocera, Ceratitis, Anastrepha, and Rhagoletis). In doing so, we aim to illustrate the theoretical and practical considerations needed to study tephritid movement. MRR studies make use of traps to directly estimate the distance that tephritid species can move within a generation and to evaluate the ecological and physiological factors that influence dispersal patterns. MRR studies, however, require careful planning to ensure that the results obtained are not biased by the methods employed, including marking methods, trap properties, trap spacing, and spatial extent of the trapping array. Despite these obstacles, MRR remains a powerful tool for determining tephritid movement, with data particularly required for understudied species that affect developing countries. To ensure that future MRR studies are successful, we suggest that site selection be carefully considered and sufficient resources be allocated to achieve optimal spacing and placement of traps in line with the stated aims of each study. An alternative to MRR is to make use of indirect methods for determining movement, or more correctly, gene flow, which have become widely available with the development of molecular tools. Key to these methods is the trapping and sequencing of a suitable number of individuals to represent the genetic diversity of the sampled population and investigate population structuring using nuclear genomic markers or non-recombinant mitochondrial DNA markers. Microsatellites are currently the preferred marker for detecting recent population displacement and provide genetic information that may be used in assignment tests for the direct determination of contemporary movement. Neither MRR nor molecular methods, however, are able to monitor fine-scale movements of individual flies. Recent developments in the miniaturization of electronics offer the tantalising possibility to track individual movements of insects using harmonic radar. Computer vision and radio frequency identification tags may also permit the tracking of fine-scale movements by tephritid flies by automated resampling, although these methods come with the same problems as traditional traps used in MRR studies. Although all methods described in this chapter have limitations, a better understanding of tephritid movement far outweighs the drawbacks of the individual methods because of the need for this information to manage tephritid populations.
Resumo:
The effectiveness of any trapping system is highly dependent on the ability to accurately identify the specimens collected. For many fruit fly species, accurate identification (= diagnostics) using morphological or molecular techniques is relatively straightforward and poses few technical challenges. However, nearly all genera of pest tephritids also contain groups of species where single, stand-alone tools are not sufficient for accurate identification: such groups include the Bactrocera dorsalis complex, the Anastrepha fraterculus complex and the Ceratitis FAR complex. Misidentification of high-impact species from such groups can have dramatic consequences and negate the benefits of an otherwise effective trapping program. To help prevent such problems, this chapter defines what is meant by a species complex and describes in detail how the correct identification of species within a complex requires the use of an integrative taxonomic approach. Integrative taxonomy uses multiple, independent lines of evidence to delimit species boundaries, and the underpinnings of this approach from both the theoretical speciation literature and the systematics/taxonomy literature are described. The strength of the integrative approach lies in the explicit testing of hypotheses and the use of multiple, independent species delimitation tools. A case is made for a core set of species delimitation tools (pre- and post-zygotic compatibility tests, multi-locus phylogenetic analysis, chemoecological studies, and morphometric and geometric morphometric analyses) to be adopted as standards by tephritologists aiming to resolve economically important species complexes. In discussing the integrative approach, emphasis is placed on the subtle but important differences between integrative and iterative taxonomy. The chapter finishes with a case study that illustrates how iterative taxonomy applied to the B. dorsalis species complex led to incorrect taxonomic conclusions, which has had major implications for quarantine, trade, and horticultural pest management. In contrast, an integrative approach to the problem has resolved species limits in this taxonomically difficult group, meaning that robust diagnostics are now available.
Resumo:
Jumping the Gun is a play written for secondary school audiences. It follows the lives of three senior school students as they navigate moral, ethical and personal choices during the final year of school.
Resumo:
For zygosity diagnosis in the absence of genotypic data, or in the recruitment phase of a twin study where only single twins from same-sex pairs are being screened, or to provide a test for sample duplication leading to the false identification of a dizygotic pair as monozygotic, the appropriate analysis of respondents' answers to questions about zygosity is critical. Using data from a young adult Australian twin cohort (N = 2094 complete pairs and 519 singleton twins from same-sex pairs with complete responses to all zygosity items), we show that application of latent class analysis (LCA), fitting a 2-class model, yields results that show good concordance with traditional methods of zygosity diagnosis, but with certain important advantages. These include the ability, in many cases, to assign zygosity with specified probability on the basis of responses of a single informant (advantageous when one zygosity type is being oversampled); and the ability to quantify the probability of misassignment of zygosity, allowing prioritization of cases for genotyping as well as identification of cases of probable laboratory error. Out of 242 twins (from 121 like-sex pairs) where genotypic data were available for zygosity confirmation, only a single case was identified of incorrect zygosity assignment by the latent class algorithm. Zygosity assignment for that single case was identified by the LCA as uncertain (probability of being a monozygotic twin only 76%), and the co-twin's responses clearly identified the pair as dizygotic (probability of being dizygotic 100%). In the absence of genotypic data, or as a safeguard against sample duplication, application of LCA for zygosity assignment or confirmation is strongly recommended.
Resumo:
Bats have been found to harbor a number of new emerging viruses with zoonotic potential and there has been a great deal of interest in identifying novel bat pathogens to determine risk to human and animal health. Many groups have identified novel viruses in bats by detection of viral nucleic acid, however virus isolation is still a challenge and there are few reports of viral isolates from bats. In recent years, our group has developed optimized procedures for virus isolation from bat urine, including the use of primary bat cells. In previous reports we have described the isolation of Hendra virus, Menangle virus and Cedar virus, in Queensland, Australia. Here, we report the isolation of four additional novel bat paramyxoviruses from urine collected from beneath pteropid bat (flying fox) colonies in Queensland and New South Wales during 2009-2011.
Resumo:
The importance of journalism to civil society is constantly proclaimed, but empirical evidence on journalism's impact, and how this operates, is surprisingly thin. Indeed, there is confusion even about what is meant by the term “impact”. Meanwhile, the issue of the role of journalism is becoming increasingly urgent as a consequence of the rapid changes engulfing the news media, brought about by technological change and the flow-on effect to the traditional advertising-supported business model. Assessing the impact of journalism has recently been the topic of debate among practitioners and scholars particularly in the United States, where philanthropists have responded to the perceived crisis in investigative journalism by funding not-for-profit newsrooms, with resulting new pressures being placed on journalists and editors to quantify their impact on society. These recent attempts have so far failed to achieve clarity or a satisfactory conclusion, which is not surprising given the complex web of causation within which journalism operates. In this paper, the authors propose a stratified definition of journalistic impact and function. They propose a methodology for studying impact drawing on realistic evaluation—a theory-based approach developed primarily to assess large social programmes occurring in open systems. The authors argue this could allow a conceptual and methodological advance on the question of media impacts, leading to research capable of usefully informing responses at a time of worrying change.
Resumo:
Background Epidemiological studies suggest a potential role for obesity and determinants of adult stature in prostate cancer risk and mortality, but the relationships described in the literature are complex. To address uncertainty over the causal nature of previous observational findings, we investigated associations of height- and adiposity-related genetic variants with prostate cancer risk and mortality. Methods We conducted a case–control study based on 20,848 prostate cancers and 20,214 controls of European ancestry from 22 studies in the PRACTICAL consortium. We constructed genetic risk scores that summed each man’s number of height and BMI increasing alleles across multiple single nucleotide polymorphisms robustly associated with each phenotype from published genome-wide association studies. Results The genetic risk scores explained 6.31 and 1.46 % of the variability in height and BMI, respectively. There was only weak evidence that genetic variants previously associated with increased BMI were associated with a lower prostate cancer risk (odds ratio per standard deviation increase in BMI genetic score 0.98; 95 % CI 0.96, 1.00; p = 0.07). Genetic variants associated with increased height were not associated with prostate cancer incidence (OR 0.99; 95 % CI 0.97, 1.01; p = 0.23), but were associated with an increase (OR 1.13; 95 % CI 1.08, 1.20) in prostate cancer mortality among low-grade disease (p heterogeneity, low vs. high grade <0.001). Genetic variants associated with increased BMI were associated with an increase (OR 1.08; 95 % CI 1.03, 1.14) in all-cause mortality among men with low-grade disease (p heterogeneity = 0.03). Conclusions We found little evidence of a substantial effect of genetically elevated height or BMI on prostate cancer risk, suggesting that previously reported observational associations may reflect common environmental determinants of height or BMI and prostate cancer risk. Genetically elevated height and BMI were associated with increased mortality (prostate cancer-specific and all-cause, respectively) in men with low-grade disease, a potentially informative but novel finding that requires replication.
Resumo:
The mechanical properties of amorphous alloys have proven both scientifically unique and of potential practical interest, although the underlying deformation physics of these materials remain less firmly established as compared with crystalline alloys. In this article, we review recent advances in understanding the mechanical behavior of metallic glasses, with particular emphasis on the deformation and fracture mechanisms. Atomistic as well as continuum modeling and experimental work on elasticity, plastic flow and localization, fracture and fatigue are all discussed, and theoretical developments are connected, where possible, with macroscopic experimental responses. The role of glass structure on mechanical properties, and conversely, the effect of deformation upon glass structure, are also described. The mechanical properties of metallic glass-derivative materials – including in situ and ex situ composites, foams and nanocrystal-reinforced glasses – are reviewed as well. Finally, we identify a number of important unresolved issues for the field.
Resumo:
Tutkimus käsittelee Porkkanamafiaksi nimetyn kansalaisliikehdinnän alkuvaiheita ja organisoitumista Suomessa. Toimintaryhmä sai alkunsa Suomessa loppukesällä vuonna 2008, jolloin idea uudenlaisesta toimintamallista levisi sosiaalisen median kautta Yhdysvalloista. Uudenlaista kuluttaja-aktiivisuutta korostanut toiminta-ajatus konkretisoitui varsin nopeasti tempaukseksi, johon osallistui satoja ihmisiä. Organisoimisessa on hyödynnetty internetin sovelluksia tehokkaasti, mikä on vaikuttanut Porkkanamafian toiminnan luonteeseen ja nopeaan leviämiseen. Tapaustutkimus Porkkanamafiasta keskittyy tarkastelemaan kansalaistoiminnan syntyprosesseja ja sijoittuu yhteiskunnallisten liikkeiden tutkimuksen kenttään. Lähtökohtana tutkimuksessa on prosessin empiirinen kuvaus. Toiminnan alkuvaiheen organisoitumista, idean kehittymistä konkreettiseksi toiminnaksi ja ihmisten rekrytoitumista mukaan toimintaan kuvataan Doug McAdamin liikehdinnän syntyä käsittelevän mallin pohjalta. Mallia on tarpeen myös täydentää ottamalla huomioon internetin ja sosiaalisen median vaikutukset. Porkkanamafian toiminnan piirteiden ja syntyprosessien tarkastelu avaa näkökulman siihen, miten kansalaistoiminta toteutuu Suomessa internet-ajalla. Tutkimusta varten olen haastatellut seitsemää Helsingin Porkkanamafian toimijaa sekä kerännyt aineistoa osallistuvan havainnoinnin avulla. Haastattelumateriaalin ja kenttähavaintojen lisäksi olen hyödyntänyt aineistona toimintaa käsitteleviä verkkosivustoja ja-julkaisuja. Tutkimuksen mukaan Porkkanamafian toiminta sijoittuu niin kutsutun perinteisen kansalaistoiminnan ja uudenlaisen verkkoaktivismin välimaastoon. Internet ja erityisesti sosiaalinen media ovat keskeisiä areenoita toiminnan organisoimiseen ja kannattajien mobilisoimiseen. Toiminnan onnistumisen kannalta olennaista on kuitenkin saada ihmiset mukaan tempauksiin, jotka edellyttävät fyysistä läsnäoloa. Porkkanamafian toiminta on internet-vahvisteista eli pääasiallinen toiminta-areena ei ole verkossa, vaikka organisoinnissa hyödynnetään monipuolisesti uutta tieto- ja viestintäteknologiaa. Tutkimus osoittaa, että internetillä ja sen erilaisilla sovelluksilla oli merkittävä asema Porkkanamafian toiminnan syntyvaiheessa. Niiden vaikutus oli keskeinen niin toimintaidean saapumisessa Suomeen, sen omaksumisessa toteutettavaksi kuin itse toiminnan leviämisessä ja organisoimisessa. Rekrytoitumis- ja mobilisaatioprosesseissa internet ja sosiaalisen median valmiit verkostot mahdollistavat ihmisten tavoittamisen nopeasti ilman kustannuksia. Nämä kanavat muokkaavat myös osallistumisen kulttuuria, sillä toimintaa koskevan tiedon levitessä verkossa innostus lähteä mukaan liikehdintään alkaa usein ennestään tuntemattomien henkilöiden kautta. Tukea oman toiminnan oikeellisuudesta saadaan läheisten ihmisten sijaan verkkoyhteisöjen massoilta. Porkkanamafian kaitaisessa epämuodollisessa kansalaistoiminnassa osallistuminen on mahdollista tapahtumakohtaisesti omien resurssien mukaan ja ilman pitkäaikaista sitoutumista. Osallistuminen ei myöskään vaadi yhteisen laaja-alaisen ideologian jakamista. Nämä nykyliikehdinnän piirteet mahdollistavat helpon osallistumisen ja madaltavat näin kynnystä lähteä mukaan toimintaan. Keskeistä yhteiskunnallisen liikehdinnän syntyprosessissa on uusi ja innovatiivinen toimintaidea, joka Porkkanamafialla on ollut niin kutsuttu käänteinen tai positiivinen boikotti eli yrittäjien kannustaminen ympäristön tilaa parantaviin toimenpiteisiin kuluttajien ostovoiman avulla.
Resumo:
Constant stress compression creep experiments were carried out on high purity alumina composites with spinel contents of 8 and 30%, corresponding to a situation with isolated and interconnected second phases. The creep experiments were conducted over a stress and temperature range of 10 to 150 MPa and 1623 to 1723 K, respectively. Analysis of the experimental data indicated that the variation in spinel content did not have any influence on high temperature deformation in the composite. The spinel phase retards grain growth, and this may enhance superplasticity in alumina-spinel composites.
Resumo:
The phenomenon of superplasticity has been demonstrated in several zirconia-alumina composites. However, the rate controlling mechanism has not yet been unambiguously identified, due to the limited data available on these materials in comparison with 3 mol% yttria stabilized tetragonal zirconia (3YTZ). The limited data on a zirconia-20 wt% alumina (3Y20A) composite suggest that the mechanical characteristics are similar to those of 3YTZ. The present experimental study on 3Y20A reveals the occurrence of diffusion creep. The experimental results are examined critically in terms of dislocation activity and diffusion creep, and their relevance to superplastic deformation.
Resumo:
There is considerable interest currently in developing magnesium based alloys as replacements for aluminum alloys in automobile applications, due to their high specific strength as compared to aluminum alloys. However, the poor formability of magnesium alloys has restricted their applications; superplasticity can be utilized to form components with complex shapes. In the present study, the compressive deformation characteristics of a Mg-0.8 wt% Al alloy with an initial grain size of 19 +/- 1.0 mum have been studied in the temperature range of 623-673 K and at strain rates ranging from 10(-7) to 10(-3) s(-1). The stress exponent was observed to decrease with a decrease in stress. The results are analyzed in terms of the existing theoretical models for high temperature deformation. Furthermore, the potential for superplasticity in this alloy is explored, based on the mechanical and microstructural characteristics of the alloy.