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1.
PLoS One ; 19(2): e0297487, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38412199

RESUMO

Global rises in precarious labour conditions have prompted further empirical work in Decent Work, a special category of employment characterised by equitable pay, treatment, and healthy working conditions. Despite this, research has tended to be conducted in developed countries with privileged groups such as those with typical working arrangements and rely on psychologically framed individual characteristics to explain marginalising factors. We propose a more sociologically framed, spatialised perspective on Decent Work which posits that marginalising factors are spatially variable and determined but moderated by employability empowerment. We measure our propositions across three spatially different sites of Vietnam through (1) a survey of minority ethnic students and graduates (N = 1071) and (2) a survey of stakeholders involved in the recruitment and employment of this group (N = 204). We find support for most of our propositions and call for more spatialised empirical work in the field of Decent Work.


Assuntos
Emprego , Grupos Minoritários , Humanos , Adolescente , Vietnã
2.
Anal Chem ; 94(32): 11315-11320, 2022 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-35930735

RESUMO

A cheap, versatile, readily modified, and reusable glass probe system enabling delivery of solid air-/moisture-sensitive samples for mass spectrometric (MS) analysis using an Atmospheric pressure Solids Analysis Probe (ASAP) is described. The simplicity of the design allows quick and easy ASAP MS analyses of sensitive solid and liquid samples without the need for any modifications to commercially available vertically loaded ASAP mass spectrometers. A comparison of ASAP mass spectra obtained for metal complexes under air and an inert atmosphere is given.


Assuntos
Atmosfera , Pressão Atmosférica , Espectrometria de Massas/métodos
3.
Int J Mol Sci ; 23(6)2022 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-35328775

RESUMO

The extraction of electron-liquid phase cross-sections (surface and bulk) is proposed through the measurement of (differential) energy loss spectra for electrons scattered from a liquid micro-jet. The signature physical elements of the scattering processes on the energy loss spectra are highlighted using a Monte Carlo simulation technique, originally developed for simulating electron transport in liquids. Machine learning techniques are applied to the simulated electron energy loss spectra, to invert the data and extract the cross-sections. The extraction of the elastic cross-section for neon was determined within 9% accuracy over the energy range 1-100 eV. The extension toward the simultaneous determination of elastic and ionisation cross-sections resulted in a decrease in accuracy, now to within 18% accuracy for elastic scattering and 1% for ionisation. Additional methods are explored to enhance the accuracy of the simultaneous extraction of liquid phase cross-sections.


Assuntos
Elétrons , Transporte de Elétrons , Estudos de Viabilidade , Método de Monte Carlo , Fenômenos Físicos , Espalhamento de Radiação
4.
Oecologia ; 198(2): 419-430, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35067801

RESUMO

Natural landscapes are increasingly impacted by nitrogen enrichment from aquatic and airborne pollution sources. Nitrogen enrichment in the environment can eliminate the net benefits that plants gain from nitrogen-fixing microbes such as rhizobia, potentially altering host-mediated selection on nitrogen fixation. However, we know little about the long-term effects of nitrogen enrichment on this critical microbial service. Here, we sampled populations of the legume Acmispon strigosus and its associated soil microbial communities from sites spanning an anthropogenic nitrogen deposition gradient. We measured the net growth benefits plants obtained from their local soil microbial communities and quantified plant investment into nodules that house nitrogen-fixing rhizobia. We found that plant growth benefits from sympatric soil microbes did not vary in response to local soil nitrogen levels, and instead varied mainly among plant lines. Soil nitrogen levels positively predicted the number of nodules formed on sympatric plant hosts, although this was likely due to plant genotypic variation in nodule formation, rather than variation among soil microbial communities. The capacity of all the tested soil microbial communities to improve plant growth is consistent with plant populations imposing strong selection on rhizobial nitrogen fixation despite elevated soil nitrogen levels, suggesting that host control traits in A. strigosus are stable under long-term nutrient enrichment.


Assuntos
Fabaceae , Rhizobium , Nitrogênio , Fixação de Nitrogênio , Rhizobium/fisiologia , Solo , Simbiose/fisiologia
5.
Int J Mol Sci ; 21(18)2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32971806

RESUMO

Electron scattering cross sections for pyridine in the energy range 0-100 eV, which we previously measured or calculated, have been critically compiled and complemented here with new measurements of electron energy loss spectra and double differential ionization cross sections. Experimental techniques employed in this study include a linear transmission apparatus and a reaction microscope system. To fulfill the transport model requirements, theoretical data have been recalculated within our independent atom model with screening corrected additivity rule and interference effects (IAM-SCAR) method for energies above 10 eV. In addition, results from the R-matrix and Schwinger multichannel with pseudopotential methods, for energies below 15 eV and 20 eV, respectively, are presented here. The reliability of this complete data set has been evaluated by comparing the simulated energy distribution of electrons transmitted through pyridine, with that observed in an electron-gas transmission experiment under magnetic confinement conditions. In addition, our representation of the angular distribution of the inelastically scattered electrons is discussed on the basis of the present double differential cross section experimental results.


Assuntos
Elétrons , Modelos Químicos , Piridinas/química , Transporte de Elétrons
6.
Nurse Res ; 28(3): 10-15, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32103651

RESUMO

BACKGROUND: Conceptual frameworks are central to doctoral nursing theses; they include the pragmatic and philosophical elements of the research design and their interrelationships. While the research process may seem to stem in a straightforward, linear manner from the research question, it is a more complex iterative enterprise. AIM: To build on Durham et al ( 2015 ) by reviewing the ostensibly static nature of research design and associated philosophical elements of the conceptual framework, reconsidering these in relation to the iterative nature of the research process, and translating these into implications for presenting the final draft of a doctoral nursing thesis. DISCUSSION: All doctoral nursing theses will have limitations and experience difficulties. They do not follow a rigid, sequential process with a defined start and end, but progress tentatively, with the relationship between the elements of the research design and philosophical assumptions following an iterative process. CONCLUSION: The research design element of the conceptual framework of doctoral nursing theses should reflect the iterative reality of the process and the associated interrelationships that occur. IMPLICATIONS FOR PRACTICE: The absence in doctoral nursing theses of a full description of the philosophical and iterative processes of the research architecture and conceptual framework weakens the transparency of the research. Therefore, doctoral nursing students need to move beyond simple description of their inductive or deductive position and research design to help develop trust and confidence in their research.


Assuntos
Dissertações Acadêmicas como Assunto/normas , Educação de Pós-Graduação em Enfermagem/métodos , Educação de Pós-Graduação em Enfermagem/organização & administração , Guias como Assunto , Pesquisa em Enfermagem/métodos , Pesquisa em Enfermagem/organização & administração , Projetos de Pesquisa , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
7.
Proc Biol Sci ; 287(1919): 20192549, 2020 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-31992172

RESUMO

Bacterial mutualists generate major fitness benefits for eukaryotes, reshaping the host phenotype and its interactions with the environment. Yet, microbial mutualist populations are predicted to generate mutants that defect from providing costly services to hosts while maintaining the capacity to exploit host resources. Here, we examined the mutualist service of symbiotic nitrogen fixation in a metapopulation of root-nodulating Bradyrhizobium spp. that associate with the native legume Acmispon strigosus. We quantified mutualism traits of 85 Bradyrhizobium isolates gathered from a 700 km transect in California spanning 10 sampled A. strigosus populations. We clonally inoculated each Bradyrhizobium isolate onto A. strigosus hosts and quantified nodulation capacity and net effects of infection, including host growth and isotopic nitrogen concentration. Six Bradyrhizobium isolates from five populations were categorized as ineffective because they formed nodules but did not enhance host growth via nitrogen fixation. Six additional isolates from three populations failed to form root nodules. Phylogenetic reconstruction inferred two types of mutualism breakdown, including three to four independent losses of effectiveness and five losses of nodulation capacity on A. strigosus. The evolutionary and genomic drivers of these mutualism breakdown events remain poorly understood.


Assuntos
Fabaceae/microbiologia , Rhizobium/fisiologia , Evolução Biológica , Bradyrhizobium , Nódulos Radiculares de Plantas/microbiologia , Simbiose
8.
Curr Biol ; 29(18): R868-R871, 2019 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-31550470

RESUMO

Parasitic plants in the genus Striga bedevil crop production throughout Africa and Asia. A new genome assembly reveals how repurposing of developmental pathways, gene gains and losses, and horizonal gene transfer all contributed to the evolution of these destructive pathogens.


Assuntos
Parasitos , Striga , África , Animais , Ásia , Genômica
9.
Ecol Lett ; 22(6): 914-924, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30887662

RESUMO

Microbial symbionts exhibit broad genotypic variation in their fitness effects on hosts, leaving hosts vulnerable to costly partnerships. Interspecific conflict and partner-maladaptation are frameworks to explain this variation, with different implications for mutualism stability. We investigated the mutualist service of nitrogen fixation in a metapopulation of root-nodule forming Bradyrhizobium symbionts in Acmispon hosts. We uncovered Bradyrhizobium genotypes that provide negligible mutualist services to hosts and had superior in planta fitness during clonal infections, consistent with cheater strains that destabilise mutualisms. Interspecific conflict was also confirmed at the metapopulation level - by a significant negative association between the fitness benefits provided by Bradyrhizobium genotypes and their local genotype frequencies - indicating that selection favours cheating rhizobia. Legumes have mechanisms to defend against rhizobia that fail to fix sufficient nitrogen, but these data support predictions that rhizobia can subvert plant defenses and evolve to exploit hosts.


Assuntos
Bradyrhizobium , Fabaceae , Rhizobium , Evolução Biológica , Fixação de Nitrogênio , Simbiose
10.
Sci Rep ; 8(1): 2226, 2018 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-29396503

RESUMO

We derive third-order transport coefficients of skewness for a phase-space kinetic model that considers the processes of scattering collisions, trapping, detrapping and recombination losses. The resulting expression for the skewness tensor provides an extension to Fick's law which is in turn applied to yield a corresponding generalised advection-diffusion-skewness equation. A physical interpretation of trap-induced skewness is presented and used to describe an observed negative skewness due to traps. A relationship between skewness, diffusion, mobility and temperature is formed by analogy with Einstein's relation. Fractional transport is explored and its effects on the flux transport coefficients are also outlined.

11.
Eur J Mass Spectrom (Chichester) ; 24(1): 74-80, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29233000

RESUMO

A novel method has been developed that enables chemical compounds to be transferred from an inert atmosphere glove box and into the atmospheric pressure ion source of a mass spectrometer whilst retaining a controlled chemical environment. This innovative method is simple and cheap to implement on some commercially available mass spectrometers. We have termed this approach inert atmospheric pressure solids analysis probe ( iASAP) and demonstrate the benefit of this methodology for two air-/moisture-sensitive chemical compounds whose characterisation by mass spectrometry is now possible and easily achieved. The simplicity of the design means that moving between iASAP and standard ASAP is straightforward and quick, providing a highly flexible platform with rapid sample turnaround.

12.
Phys Rev E ; 95(4-1): 042119, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28505754

RESUMO

A generalized phase-space kinetic Boltzmann equation for highly nonequilibrium charged particle transport via localized and delocalized states is used to develop continuity, momentum, and energy balance equations, accounting explicitly for scattering, trapping and detrapping, and recombination loss processes. Analytic expressions detail the effect of these microscopic processes on mobility and diffusivity. Generalized Einstein relations (GER) are developed that enable the anisotropic nature of diffusion to be determined in terms of the measured field dependence of the mobility. Interesting phenomena such as negative differential conductivity and recombination heating and cooling are shown to arise from recombination loss processes and the localized and delocalized nature of transport. Fractional transport emerges naturally within this framework through the appropriate choice of divergent mean waiting time distributions for localized states, and fractional generalizations of the GER and mobility are presented. Signature impacts on time-of-flight current transients of recombination loss processes via both localized and delocalized states are presented.

13.
Appl Environ Microbiol ; 82(17): 5259-68, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27316960

RESUMO

UNLABELLED: Rhizobia are best known for nodulating legume roots and fixing atmospheric nitrogen for the host in exchange for photosynthates. However, the majority of the diverse strains of rhizobia do not form nodules on legumes, often because they lack key loci that are needed to induce nodulation. Nonnodulating rhizobia are robust heterotrophs that can persist in bulk soil, thrive in the rhizosphere, or colonize roots as endophytes, but their role in the legume-rhizobium mutualism remains unclear. Here, we investigated the effects of nonnodulating strains on the native Acmispon-Bradyrhizobium mutualism. To examine the effects on both host performance and symbiont fitness, we performed clonal inoculations of diverse nonnodulating Bradyrhizobium strains on Acmispon strigosus hosts and also coinoculated hosts with mixtures of sympatric nodulating and nonnodulating strains. In isolation, nonnodulating Bradyrhizobium strains did not affect plant performance. In most cases, coinoculation of nodulating and nonnodulating strains reduced host performance compared to that of hosts inoculated with only a symbiotic strain. However, coinoculation increased host performance only under one extreme experimental treatment. Nearly all estimates of nodulating strain fitness were reduced in the presence of nonnodulating strains. We discovered that nonnodulating strains were consistently capable of coinfecting legume nodules in the presence of nodulating strains but that the fitness effects of coinfection for hosts and symbionts were negligible. Our data suggest that nonnodulating strains most often attenuate the Acmispon-Bradyrhizobium mutualism and that this occurs via competitive interactions at the root-soil interface as opposed to in planta IMPORTANCE: Rhizobia are soil bacteria best known for their capacity to form root nodules on legume plants and enhance plant growth through nitrogen fixation. Yet, most rhizobia in soil do not have this capacity, and their effects on this symbiosis are poorly understood. We investigated the effects of diverse nonnodulating rhizobia on a native legume-rhizobium symbiosis. Nonnodulating strains did not affect plant growth in isolation. However, compared to inoculations with symbiotic rhizobia, coinoculations of symbiotic and nonnodulating strains often reduced plant and symbiont fitness. Coinoculation increased host performance only under one extreme treatment. Nonnodulating strains also invaded nodule interiors in the presence of nodulating strains, but this did not affect the fitness of either partner. Our data suggest that nonnodulating strains may be important competitors at the root-soil interface and that their capacity to attenuate this symbiosis should be considered in efforts to use rhizobia as biofertilizers.


Assuntos
Bradyrhizobium/fisiologia , Fabaceae/microbiologia , Rhizobium/fisiologia , Nódulos Radiculares de Plantas/microbiologia , Simbiose , Fabaceae/fisiologia , Fixação de Nitrogênio , Rizosfera , Nódulos Radiculares de Plantas/fisiologia , Microbiologia do Solo
14.
Phys Rev E ; 93(3): 032119, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27078304

RESUMO

We present a general phase-space kinetic model for charged-particle transport through combined localized and delocalized states, capable of describing scattering collisions, trapping, detrapping, and losses. The model is described by a generalized Boltzmann equation, for which an analytical solution is found in Fourier-Laplace space. The velocity of the center of mass and the diffusivity about it are determined analytically, together with the flux transport coefficients. Transient negative values of the free particle center-of-mass transport coefficients can be observed due to the trapping to, and detrapping from, localized states. A Chapman-Enskog-type perturbative solution technique is applied, confirming the analytical results and highlighting the emergence of a density gradient representation in the weak-gradient hydrodynamic regime. A generalized diffusion equation with a unique global time operator is shown to arise, reducing to the standard diffusion equation and a Caputo fractional diffusion equation in the normal and dispersive limits. A subordination transformation is used to solve the generalized diffusion equation by mapping from the solution of a corresponding standard diffusion equation.

15.
Nurse Res ; 23(2): 8-12, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26563926

RESUMO

AIM: To define conceptual frameworks and their inherent dichotomies, and integrate them with concomitant concepts to help early nursing doctoral researchers to develop their understanding of and engage with discourse further, so that nursing can demonstrate its ability to contribute to the meta-theoretical debate of doctoral research alongside other practices and theory-based disciplines. BACKGROUND: Conceptual frameworks are central to nursing doctoral studies as they map and contextualise the philosophical assumptions of the research in relation to paradigms and ontological, epistemological and methodological foundations. They shape all aspects of the research design and provide a structure for theorising. They can also be a challenge for researchers and are under-discussed in the literature. REVIEW METHODS: Literature review. DISCUSSION: The key aspects of the conceptual framework debate in terms of objectivist, subjectivist paradigms and the wider paradigm debate, including retroduction and abduction, are reviewed here together with consideration of how these apply to nursing doctoral research. CONCLUSION: Conceptual frameworks are pivotal to nursing doctoral research as they clarify and integrate philosophical, methodological and pragmatic aspects of doctoral thesis while helping the profession to be seen as a research-based discipline, comfortable with the language of meta-theoretical debate. IMPLICATIONS FOR RESEARCH/PRACTICE: Conceptual frameworks should form the methodological foundation for all nursing doctoral research.


Assuntos
Educação de Pós-Graduação em Enfermagem/organização & administração , Pesquisa em Enfermagem/organização & administração
16.
Rapid Commun Mass Spectrom ; 28(18): 2024-30, 2014 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-25132303

RESUMO

RATIONALE: The atmospheric pressure solids analysis probe (ASAP) has been successfully introduced into laboratories as a routine analytical tool but the technique is labour-intensive and is not easily automated. This paper describes the modifications made to an existing atmospheric pressure gas chromatography (APGC) system to enable the automated analysis of samples that would have otherwise been analysed by ASAP. METHODS: Liquid samples were injected into a 1 m piece of fused silica guard column using a standard split/splitless gas chromatography (GC) inlet, oven and autosampler. A novel timing delay circuit was developed and integrated into the system to control acquisition start times and a bespoke heating block/calibrant delivery system was used to transport either the calibration or reference compound into the ionisation source. RESULTS: The modified system has allowed the successful analysis of those samples requiring ASAP to be carried out in a fully automated manner using APGc. The analysis is rapid and can be carried out in less than 2 min. The results obtained are directly comparable with those obtained by ASAP. A typical mass accuracy of better than 5 mm/z units was achieved, allowing the molecules to be identified based on their elemental formulae. CONCLUSIONS: An existing APGC system has been successfully modified and is suitable for the automatic analysis of samples normally analysed by ASAP. The APGC instrument incorporates the use of a novel reference compound and delivery system which allows accurate mass measurements to be performed. This and the other modifications described have allowed the technique to be incorporated into an existing suite of mass spectrometry-based experiments for use in the characterisation of organic molecules.

17.
Forensic Sci Int Genet ; 7(1): 1-9, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21683667

RESUMO

Mitochondrial DNA is commonly used in identity testing for the analysis of old or degraded samples or to give evidence of familial links. The Abbott T5000 mass spectrometry platform provides an alternative to the more commonly used Sanger sequencing for the analysis of human mitochondrial DNA. The robustness of the T5000 system has previously been demonstrated using DNA extracted from volunteer buccal swabs but the system has not been tested using more challenging sample types. For mass spectrometry to be considered as a valid alternative to Sanger sequencing it must also be demonstrated to be suitable for use with more limiting sample types such as old teeth, bone fragments, and hair shafts. In 2009 the Commonwealth War Graves Commission launched a project to identify the remains of 250 World War I soldiers discovered in a mass grave in Fromelles, France. This study characterises the performance of both Sanger sequencing and the T5000 platform for the analysis of the mitochondrial DNA extracted from 225 of these remains, both in terms of the ability to amplify and characterise DNA regions of interest and the relative information content and ease-of-use associated with each method.


Assuntos
Osso e Ossos/metabolismo , DNA Mitocondrial/genética , Análise de Sequência de DNA , Espectrometria de Massas por Ionização por Electrospray/métodos , I Guerra Mundial , Humanos , Reação em Cadeia da Polimerase , Reprodutibilidade dos Testes
18.
Nurs Stand ; 27(8): 43-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23189601

RESUMO

AIM: To explore whether additional teaching and simulated learning of one-hour duration could improve the blood pressure measurement skills of nursing students. METHOD: A post-test experimental method was used to measure the outcome of additional, targeted simulated learning of blood pressure monitoring beyond normal curriculum content in adult branch nursing students in module one of a three-year nursing programme. RESULTS: One hour of additional teaching and simulated learning improved the ability of nursing students to measure blood pressure accurately, with the data revealing a statistical difference between experimental and control groups in the systolic and diastolic accuracy of blood pressure monitoring. CONCLUSION: In a changing practice environment with fewer opportunities to develop clinical skills under supervision, there is a need for nurse educators and mentors to reconsider and research further methods used for blood pressure monitoring and other skills teaching using simulation for effective learning and skills acquisition.


Assuntos
Pressão Sanguínea , Competência Clínica , Aprendizagem , Enfermagem , Currículo , Humanos
19.
J Am Soc Mass Spectrom ; 23(5): 850-7, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22290485

RESUMO

LC ESI FTICR MS of a sample of cediranib identified this pharmaceutical target molecule plus an additional 10 compounds of interest, all of which were less than 10% total ion current (TIC) peak intensity relative to cediranib. LC FTICR tandem mass spectrometry using electron induced dissociation (EID) has been achieved and has proven to be the best way to generate useful product ion information for all of these singly protonated molecules. Cediranib [M + H](+) fragmented by EID to give 29 product ions whereas QTOF-CID generated only one very intense product ion, and linear ion trap-CID, which generated 10 product ions, but all with poor S/N. Twenty-six of the EID product ions were unique to this fragmentation technique alone. By considering the complementary LC-EID and LC-CID data together, all 10 unknown compounds were structurally characterized and proven to be analogous to cediranib. Of particular importance, EID produced unique product ion information for one of the low level cediranib analogues that enabled full characterization of the molecule such that the presence of an extra propylpyrrolidine group was discovered and proven to be located on the pyrrolidine ring of cediranib, solving an analytical problem that could not be solved by collision induced dissociation (CID). Thus, it has been demonstrated that EID is in harmony with the chromatography duty-cycle and the dynamic concentration range of synthetic compounds containing trace impurities, providing crucial analytical information that cannot be obtained by more traditional methodologies.


Assuntos
Cromatografia Líquida/métodos , Modelos Químicos , Preparações Farmacêuticas/química , Espectrometria de Massas em Tandem/métodos , Química Orgânica/métodos , Razão Sinal-Ruído
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