282 research outputs found

    Identificación de compuestos volátiles de tres especies de Cyathodium (Marchantiophyta: Cyathodiaceae) y Leiosporoceros dussii(Anthocerotophyta: Leiosporocerotaceae) de Panama y C. foetidissimum de Costa Rica

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    Cyathodium is a thalloid marchantialean liverwort with five species reported for the Neotropics. Three species that occur in Panama (C. bischlerianum, C. spruceanum, C. cavernarum) and one from Costa Rica (C. foetidissimum) were studied chemically. Female and male plants of the dioecious C. spruceanum were very similar in their chemical composition except for two compounds that were found only in female plants. All samples of C. spruceanum and C. bischlerianum contained, in less than three percent, the sesquiterpenes germacrene D and bicyclogermacrene. The presence of these compounds suggests a close affinity between these two species. Cyathodium bischlerianum contained mainly aromatic monoterpenes with nerolidol as the main compound. Cyathodium cavernarum also had a very distinct chemical composition with an octane derivative as its major compound. Indole compounds were found only in C. foetidissimum. The presence of these compounds in plants from Costa Rica and Tahiti suggests that they could be considered as potential chemosystematic markers for the species. Based on their chemical composition there is a clear distinction between the four species of Cyathodium studied. The chemistry of these species supports previous morphological and genetic studies. Only two compounds could be identified in Leiosporoceros dussii. There is a need for additional genetic and chemical studies on neotropical Cyathodium and Leiosporoceros. Key Identificación de compuestos volátiles de tres especies de Cyathodium (Marchantiophyta: Cyathodiaceae) y Leiosporoceros dussii (Anthocerotophyta: Leiosporocerotaceae) de Panama y C. foetidissimum de Costa Rica. Cyathodium es una hepática marchantial con cinco especies comunicadas para el Neotrópico. Se estudió la composición química de tres especies que crecen en Panamá (C. bischlerianum, C. spruceanum, C. cavernarum) y, una que crece en Costa Rica (C. foetidissimum). Plantas femeninas y masculinas del dioico C. spruceanum fueron muy similares en su composición química excepto por dos compuestos que se encontraron solo en plantas femeninas. Todas las muestras de Cyathodium spruceanum y C. bischlerianum contenían, en un porcentaje de menos del tres por ciento, los sesquiterpenos germacreno D y biciclogermacreno. La presencia de estos compuestos sugiere una afinidad muy cercana entre las dos especies. Cyathodium bischlerianum contiene principalmente monoterpenos aromáticos con nerolidol como el compuesto principal. Cyathodium cavernarum también tuvo una composición química muy distintiva con un derivado del octano como su compuesto principal. Compuestos de indol fueron encontrados solo en C. foetidissimum. La presencia de estos compuestos en plantas de Costa Rica y Tahiti sugiere que puedan ser marcadores quimosistemáticos para esta especieLas cuatro especies de Cyathodium estudiadas se pueden distinguir de acuerdo con su composición química. La química de estas especies apoya estudios genéticos y morfológicos previos. Solo dos compuestos pudieron ser identificados en Leiosporoceros dussii. Se necesitan estudios genéticos y químicos adicionales para los Cyathodium y Leiosporoceros neotropicales

    Improving pod borer complex tolerance in cultivated pigeonpea(Cajanuscajan)by using wild Cajanusspecies

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    Pod borer (Helicoverpa armigera Hübner) is the single largest yield reducing factor in food legumes. Worldwide, pod borer causes an estimated loss of over 2billionannually,despiteover2 billion annually, despite over 1 billion value of insecticides used to control this devastating pest. In pigeonpea(Cajanuscajan(L.) Millsp.), an important food grain legume crop of the semi-arid tropics, Helicoverpa armigera causes maximum yield losses (25-70%) followed by pod fly, Melanagromyzaobtusa(10-50%), Marucavitrata(5-25%) and pod bug, Clavigrallagibbosa(10-30%). High levels of resistance to pod borer is not available in the cultivated genepool, which necessitates the exploitation of new anddiverse sources of variations

    Rolling friction of a viscous sphere on a hard plane

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    A first-principle continuum-mechanics expression for the rolling friction coefficient is obtained for the rolling motion of a viscoelastic sphere on a hard plane. It relates the friction coefficient to the viscous and elastic constants of the sphere material. The relation obtained refers to the case when the deformation of the sphere ξ\xi is small, the velocity of the sphere VV is much less than the speed of sound in the material and when the characteristic time ξ/V\xi/V is much larger than the dissipative relaxation times of the viscoelastic material. To our knowledge this is the first ``first-principle'' expression of the rolling friction coefficient which does not contain empirical parameters.Comment: 6 pages, 2 figure

    A Decolonial Critique of the Racialized “Localwashing” of Extraction in Central Africa

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    Responding to calls for increased attention to actions and reactions “from above” within the extractive industry, we offer a decolonial critique of the ways in which corporate entities and multinational institutions propagate racialized rhetoric of “local” suffering, “local” consultation, and “local” fault for failure in extractive zones. Such rhetoric functions to legitimize extractive intervention within a set of practices that we call localwashing. Drawing from a decade of research on and along the Chad-Cameroon Oil Pipeline, we show how multi-scalar actors converged to assert knowledge of, responsibility for, and collaborations with “local” people within a racialized politics of scale. These corporate representations of the racialized “local” are coded through long-standing colonial tropes. We identify three interrelated and overlapping flexian elite rhetoric(s) and practices of racialized localwashing: (a) anguishing, (b) arrogating, and (c) admonishing. These elite representations of a racialized “local” reveal diversionary efforts “from above” to manage public opinion, displace blame for project failures, and domesticate dissent in a context of persistent scrutiny and criticism from international and regional advocates and activists

    Cognitive, Behavioral, and Situational Influences on Relapse to Smoking After Group Treatment for Tobacco Dependence

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    Socioeconomic disparities in treatment failure rates for evidence-based tobacco dependence treatment are well-established. Adapted cognitive behavioral treatments are extensively tailored to meet the needs of lower socioeconomic status (SES) smokers and dramatically improve early treatment success, but there is little understanding of why treatment failure occurs after a longer period of abstinence than with standard treatment, why early treatment success is not sustained, and why long-term treatment failure rates are no different from standard treatments. We sought to understand the causes of treatment failure from the perspective of diverse participants who relapsed after receiving standard or adapted treatment in a randomized control trial. We used a qualitative approach and a cognitive-behavioral framework to examine themes in responses to a semi-structured post-relapse telephone interview. The primary causes of relapse were familiar (i.e., habit, stress, unanticipated precipitating events). The adapted treatment appeared to improve the management of habits and stress short-term, but did not adequately prepare respondents for unanticipated events. Respondents reported that they would have benefited from continued support. New therapeutic targets might include innovative methods to reduce long-term treatment failure by delivering extended relapse prevention interventions to support early treatment success

    Queering Development? The Unsettling Geographies of South–South Cooperation

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    This paper deploys queer theory as a way of approaching South–South Cooperation (SSC). It examines the ways in which Southern development partners are not simply up-ending the long-standing spatialities, imaginaries and identities (re)produced through the mainstream international development regime, but queering terminologies and definitions, while presenting themselves in fluid ways, enrolling different identities and attributes in different places and to different audiences. At the same time, a queer lens reveals the (re)inscription of gendered, sexualised and racialised identities and hierarchies through the relationships, intimacies and practices of SSC. The paper proposes that queer theory can offer productive insights into the complex and compelling phenomenon of SSC, and the transgressive challenges to the postcolonial hierarchies and binaries of “traditional” international development

    Toward a geography of black internationalism: Bayard Rustin, nonviolence and the promise of Africa

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    This article charts the trip made by civil rights leader Bayard Rustin to West Africa in 1952, and examines the unpublished ‘Africa Program’ which he subsequently presented to leading American pacifists. I situate Rustin’s writings within the burgeoning literature on black internationalism which, despite its clear geographical registers, geographers themselves have as yet made only a modest contribution towards. The article argues that within this literature there remains a tendency to romanticize cross-cultural connections in lieu of critically interrogating their basic, and often competing, claims. I argue that closer attention to the geographies of black internationalism, however, allows us to shape a more diverse and practiced sense of internationalist encounter and exchange. The article reconstructs the multiplicity of Rustin’s black internationalist geographies which drew eclectically from a range of Pan-African, American and pacifist traditions. Though each of these was profoundly racialized, they conceptualized race in distinctive ways and thereby had differing understandings of what constituted the international as a geographical arena. By blending these forms of internationalism Rustin was able to promote a particular model of civil rights which was characteristically internationalist in outlook, nonviolent in principle and institutional in composition; a model which in selective and uneven ways continues to shape our understanding of the period

    What is known about the patient's experience of medical tourism? A scoping review

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    <p>Abstract</p> <p>Background</p> <p>Medical tourism is understood as travel abroad with the intention of obtaining non-emergency medical services. This practice is the subject of increasing interest, but little is known about its scope.</p> <p>Methods</p> <p>A comprehensive scoping review of published academic articles, media sources, and grey literature reports was performed to answer the question: what is known about the patient's experience of medical tourism? The review was accomplished in three steps: (1) identifying the question and relevant literature; (2) selecting the literature; (3) charting, collating, and summarizing the information. Overall themes were identified from this process.</p> <p>Results</p> <p>291 sources were identified for review from the databases searched, the majority of which were media pieces (<it>n </it>= 176). A further 57 sources were included for review after hand searching reference lists. Of the 348 sources that were gathered, 216 were ultimately included in this scoping review. Only a small minority of sources reported on empirical studies that involved the collection of primary data (<it>n </it>= 5). The four themes identified via the review were: (1) decision-making (e.g., push and pull factors that operate to shape patients' decisions); (2) motivations (e.g., procedure-, cost-, and travel-based factors motivating patients to seek care abroad); (3) risks (e.g., health and travel risks); and (4) first-hand accounts (e.g., patients' experiential accounts of having gone abroad for medical care). These themes represent the most discussed issues about the patient's experience of medical tourism in the English-language academic, media, and grey literatures.</p> <p>Conclusions</p> <p>This review demonstrates the need for additional research on numerous issues, including: (1) understanding how multiple information sources are consulted and evaluated by patients before deciding upon medical tourism; (2) examining how patients understand the risks of care abroad; (3) gathering patients' prospective and retrospective accounts; and (4) the push and pull factors, as well as the motives of patients to participate in medical tourism. The findings from this scoping review and the knowledge gaps it uncovered also demonstrate that there is great potential for new contributions to our understanding of the patient's experience of medical tourism.</p

    Modifying effect of dual antiplatelet therapy on incidence of stent thrombosis according to implanted drug-eluting stent type

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    Aim To investigate the putative modifying effect of dual antiplatelet therapy (DAPT) use on the incidence of stent thrombosis at 3 years in patients randomized to Endeavor zotarolimus-eluting stent (E-ZES) or Cypher sirolimus-eluting stent (C-SES). Methods and results Of 8709 patients in PROTECT, 4357 were randomized to E-ZES and 4352 to C-SES. Aspirin was to be given indefinitely, and clopidogrel/ticlopidine for ≥3 months or up to 12 months after implantation. Main outcome measures were definite or probable stent thrombosis at 3 years. Multivariable Cox regression analysis was applied, with stent type, DAPT, and their interaction as the main outcome determinants. Dual antiplatelet therapy adherence remained the same in the E-ZES and C-SES groups (79.6% at 1 year, 32.8% at 2 years, and 21.6% at 3 years). We observed a statistically significant (P = 0.0052) heterogeneity in treatment effect of stent type in relation to DAPT. In the absence of DAPT, stent thrombosis was lower with E-ZES vs. C-SES (adjusted hazard ratio 0.38, 95% confidence interval 0.19, 0.75; P = 0.0056). In the presence of DAPT, no difference was found (1.18; 0.79, 1.77; P = 0.43). Conclusion A strong interaction was observed between drug-eluting stent type and DAPT use, most likely prompted by the vascular healing response induced by the implanted DES system. These results suggest that the incidence of stent thrombosis in DES trials should not be evaluated independently of DAPT use, and the optimal duration of DAPT will likely depend upon stent type (Clinicaltrials.gov number NCT00476957
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