2,146 research outputs found

    Evolutionary Physiology: The extent of C4 and CAM photosynthesis in the Genera Anacampseros and Grahamia of the Portulacaceae

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    The Portulacaceae is one of the few terrestrial plant families known to have both C(4) and Crassulacean acid metabolism (CAM) species. There may be multiple origins of the evolution of CAM within the Portulacaceae but the only clear evidence of C(4) photosynthesis is found in members of the genus Portulaca. In the Portulaca, CAM succulent tissue is overlaid with the C(4) tissue in a unique fashion where both pathways are operating simultaneously. Earlier reports have shown that the clade containing the genera Anacampseros and Grahamia may also contain C(4) photosynthetic species similar to the Portulaca, which would indicate multiple origins of C(4) photosynthesis within the family. The aim of the present study was to ascertain the true photosynthetic nature of these genera. An initial survey of the carbon isotope composition of the Anacampseros ranged from -12.6 per thousand to -24.0 per thousand, indicating very little CAM activity in some species, with other values close to the C(4) range. Anacampseros (=Grahamia) australiana which had been previously identified as a C(4) species had a carbon isotope composition value of -24.0 per thousand, which is more indicative of a C(3) species with a slight contribution of CAM activity. Other Anacampseros species with C(4)-like values have been shown to be CAM plants. The initial isotope analysis of the Grahamia species gave values in the range of -27.1 per thousand to -23.6 per thousand, placing the Grahamia species well towards the C(3) photosynthetic range. Further physiological studies indicated increased night-time CO(2) uptake with imposition of water stress, associated with a large diurnal acid fluctuation and a marked increased phosphoenolpyruvate carboxylase activity. This showed that the Grahamia species are actually facultative CAM plants despite their C(3)-like carbon isotope values. The results indicate that the Grahamia and Anacampseros species do not utilize the C(4) photosynthetic pathway. This is the first to identify that the Grahamia species are facultative CAM plants where CAM can be induced by water stress. This work supports earlier physiological work that indicates that this clade containing Anacampseros and Grahamia species comprises predominantly facultative CAM plants. This report suggests there may be only one clade which contains C(4) photosynthetic members with CAM-like characteristics

    Leading in Diverse Schools: Principals\u27 Perceptions of Building Relationships with Hispanic/Latino Families

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    This study investigates principals’ perceptions about the importance and degree of building relationships with Hispanic/Latino families in highly diverse schools in an Atlanta area school district. Over the past ten years, the school district’s Hispanic/Latino student population increased by more than 12,000 students. The school district’s current Hispanic/Latino enrollment is almost 15,000 students, which is 14.4% of the total student body. Six principals from different elementary and middle schools with growing Hispanic/Latino student populations participated in this qualitative study involving in-depth, one-on-one interviews, informal observations, and artifact collection. The data analysis process involved transcribing the interview tapes verbatim, analyzing the narratives for theme categories, and identifying the common theme patterns. Critical theorists Giroux, Apple, and Freire provided the framework to examine the principals’ responses and experiences. Hegemony, patriarchy, and reciprocity are critical theory concepts used to criticize and critique the data to glean meaning and understanding of the principals’ perceptions about relationship building with Hispanic/Latino parents and families. There is a disequilibrium between what the principals say is occurring at their schools and the hidden and taken-for-granted structures that exist at their schools. Based on their actions, it seems principals perceive that in order to build relationships with Hispanic/Latino families, the school leaders need to take on a patriarchal role and explain the necessary knowledge, skills, and practices to the parents. This hegemonic behavior perpetuates the dominant group’s power and control over the non-dominant, oppressed groups. In addition, there was no indication that the principals gain an understanding of the Hispanic/Latino culture and language before attempting to help the families with parenting and schooling. The findings suggest that the principals are operating on the assumption that they know what is best for the Hispanic/Latino population without prior inquiry. There is little evidence that the principals believe they have something to learn from the Hispanic/Latino parents and families, thus, a reciprocal learning relationship is non-existent. These underlying beliefs and assumptions will hinder the principals from building a true relationship with the students, parents, and families who they serve in the school community

    Variation in Dysphagia Assessment and Management in Acute Stroke: An Interview Study

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    (1) Background: Patients with dysphagia are at increased risk of stroke-associated pneumonia. There is wide variation in the way patients are screened and assessed. The aim of this study is to explore staff opinions about current practice of dysphagia screening, assessment and clinical management in acute phase stroke. (2) Methods: Fifteen interviews were conducted in five English National Health Service hospitals. Hospitals were selected based on size and performance against national targets for dysphagia screening and assessment, and prevalence of stroke-associated pneumonia. Participants were purposefully recruited to reflect a range of healthcare professions. Data were analysed using a six-stage thematic process. (3) Results: Three meta themes were identified: delays in care, lack of standardisation and variability in resources. Patient, staff, and service factors that contribute to delays in dysphagia screening, assessment by a speech and language therapist, and delays in nasogastric tube feeding were identified. These included admission route, perceived lack of ownership for screening patients, prioritisation of assessments and staff resources. There was a lack of standardisation of dysphagia screening protocols and oral care. There was variability in staff competences and resources to assess patients, types of medical interventions, and care processes. (4) Conclusion: There is a lack of standardisation in the way patients are assessed for dysphagia and variation in practice relating to staff competences, resources and care processes between hospitals. A range of patient, staff and service factors have the potential to impact on stroke patients being assessed within the recommended national guidelines

    Experiences of dysphagia after stroke: an interview study of stroke survivors and their informal caregivers

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    (1) Background: Swallowing difficulties (dysphagia) after stroke are not uncommon and is a consistent risk factor for stroke-associated pneumonia. This interview study explores the perspectives of stroke survivors, who had their swallowing assessed in the first few days of admission to hospital, and their informal caregivers. (2) Methods: A participatory approach was used involving people affected by stroke in the interpretation and analysis of the interview data. Data was thematically analysed and six themes were identified. (3) Results: These themes included how past-future experiences may influence a person’s emotional response to events; understanding what is happening and adjustment; the impact of dysphagia; attitudes to care; communication to patients and procedural issues. (4) Conclusion: The findings highlight the importance of effective public health messages to improve people’s responsiveness to the signs of stroke, standardisation of assessment and management procedures, effective communication to patients about the consequences of dysphagia, and the impact of dysphagia on the person who had the stroke and their informal caregiver

    Factors associated with risk of stroke-associated pneumonia in patients with dysphagia: A systematic review

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    Dysphagia is associated with increased risk of stroke-associated pneumonia (SAP). However, it is unclear what other factors contribute to that risk or which measures may reduce it. This systematic review aimed to provide evidence on interventions and care processes associated with SAP in patients with dysphagia. Studies were screened for inclusion if they included dysphagia only patients, dysphagia and non-dysphagia patients or unselected patients that included dysphagic patients and evaluated factors associated with a recorded frequency of SAP. Electronic databases were searched from inception to February 2017. Eligible studies were critically appraised. Heterogeneity was evaluated using I2. The primary outcome was SAP. Eleven studies were included. Sample sizes ranged from 60 to 1088 patients. There was heterogeneity in study design. Measures of immunodepression are associated with SAP in dysphagic patients. There is insufficient evidence to justify screening for aerobic Gram-negative bacteria. Prophylactic antibiotics did not prevent SAP and proton pump inhibitors may increase risk. Treatment with metoclopramide may reduce SAP risk. Evidence that nasogastric tube (NGT) placement increases risk of SAP is equivocal. A multidisciplinary team approach and instrumental assessment of swallowing may reduce risk of pneumonia. Patients with impaired mobility were associated with increased risk. Findings should be interpreted with caution given the number of studies, heterogeneity and descriptive analyses. Several medical interventions and care processes, which may reduce risk of SAP in patients with dysphagia, have been identified. Further research is needed to evaluate the role of these interventions and care processes in clinical practice

    Impact of dysphagia assessment and management on risk of stroke-associated pneumonia: A systematic review

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    Background Patients with dysphagia are at increased risk of stroke-associated pneumonia. There is wide variation in the way patients are screened and assessed during the acute phase. The aim of this review was to identify which methods of assessment and management in acute stroke influence the risk of stroke-associated pneumonia. Studies of stroke patients that reported dysphagia screening, assessment or management and occurrence of pneumonia during acute phase stroke were screened for inclusion after electronic searches of multiple databases from inception to November 2016. The primary outcome was association with stroke-associated pneumonia. Summary Twelve studies of 87824 patients were included. The type of dysphagia screening protocol varied widely across and within studies. There was limited information on what comprised a specialist swallow assessment and alternative feeding was the only management strategy, which was reported for association with stroke-associated pneumonia. Use of a formal screening protocol, early dysphagia screening and assessment by a speech and language pathologist (SLP) was associated with a reduced risk of stroke-associated pneumonia. There was marked heterogeneity between the included studies, which precluded meta-analysis. Key Messages There is variation in assessment and management of dysphagia in acute stroke. There is increasing evidence that early dysphagia screening and specialist swallow assessment by a SLP may reduce the odds of stroke-associated pneumonia. There is the potential for other factors to influence incidence of stroke-associated pneumonia during the acute phase

    Infrared properties of Active OB stars in the Magellanic Clouds from the Spitzer SAGE Survey

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    We present a study of the infrared properties of 4922 spectroscopically confirmed massive stars in the Large and Small Magellanic Clouds, focusing on the active OB star population. Besides OB stars, our sample includes yellow and red supergiants, Wolf-Rayet stars, Luminous Blue Variables (LBVs) and supergiant B[e] stars. We detect a distinct Be star sequence, displaced to the red, and find a higher fraction of Oe and Be stars among O and early-B stars in the SMC, respectively, when compared to the LMC, and that the SMC Be stars occur at higher luminosities. We also find photometric variability among the active OB population and evidence for transitions of Be stars to B stars and vice versa. We furthermore confirm the presence of dust around all the supergiant B[e] stars in our sample, finding the shape of their spectral energy distributions (SEDs) to be very similar, in contrast to the variety of SED shapes among the spectrally variable LBVs.Comment: 5 pages, 1 figure, to appear in the proceedings of the IAUS 272 on "Active OB stars: structure, evolution, mass loss and critical limits" (Paris, July 19-23, 2010), Cambridge University Press. Editors C. Neiner, G. Wade, G. Meynet and G. Peter
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