375 research outputs found

    Nutrient enrichment induces a shift in dissolved organic carbon (DOC) metabolism in oligotrophic freshwater sediments

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    Dissolved organic carbon (DOC) turnover in aquatic environments is modulated by the presence of other key macronutrients, including nitrogen (N) and phosphorus (P). The ratio of these nutrients directly affects the rates of microbial growth and nutrient processing in the natural environment. The aim of this study was to investigate how labile DOC metabolism responds to changes in nutrient stoichiometry using 14C tracers in conjunction with untargeted analysis of the primary metabolome in upland peat river sediments. N addition led to an increase in 14C-glucose uptake, indicating that the sediments were likely to be primarily N limited. The mineralisation of glucose to 14CO2 reduced following N addition, indicating that nutrient addition induced shifts in internal carbon (C) partitioning and microbial C use efficiency (CUE). This is directly supported by the metabolomic profile data which identified significant differences in 22 known metabolites (34% of the total) and 30 unknown metabolites (16% of the total) upon the addition of either N or P. 14C-glucose addition increased the production of organic acids known to be involved in mineral P dissolution (e.g. gluconic acid, malic acid). Conversely, when N was not added, the addition of glucose led to the production of the sugar alcohols, mannitol and sorbitol, which are well known microbial C storage compounds. P addition resulted in increased levels of several amino acids (e.g. alanine, glycine) which may reflect greater rates of microbial growth or the P requirement for coenzymes required for amino acid synthesis. We conclude that inorganic nutrient enrichment in addition to labile C inputs has the potential to substantially alter in-stream biogeochemical cycling in oligotrophic freshwaters

    The subject specialist in higher education: professional engagement

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    The university subject librarians' role is at the centre of new models of teaching and learning, yet further debate and published contributions are still needed to shape its future direction. Subject Librarians: Engaging with the Learning and Teaching Environment assesses trends and challenges in current practice, and aims to encourage renewed thinking and improved approaches. Its editors and authors include experienced practitioners and academics. At a time of great change and increasing challenges in higher education this book offers directors of academic services, library managers, librarians and lecturers a chance to reflect on the key issues and consider the needs of the learning community. Subject Librarians: Engaging with the Learning and Teaching Environment also provides a perspective on current practice and a reference source for students of Information Management and Information Studie

    Rapidly Rotating Lenses: Repeating features in the lightcurves of short period binary microlenses

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    Microlensing is most sensitive to binary lenses with relatively large orbital separations, and as such, typical binary microlensing events show little or no orbital motion during the event. However, despite the strength of binary microlensing features falling off rapidly as the lens separation decreases, we show that it is possible to detect repeating features in the lightcurve of binary microlenses that complete several orbits during the microlensing event. We investigate the lightcurve features of such Rapidly Rotating Lens (RRL) events. We derive analytical limits on the range of parameters where these effects are detectable, and confirm these numerically. Using a population synthesis Galactic model we estimate the RRL event rate for a ground-based and space-based microlensing survey to be 0.32fb and 7.8fb events per year respectively, assuming year-round monitoring and where fb is the binary fraction. We detail how RRL event parameters can be quickly estimated from their lightcurves, and suggest a method to model RRL events using timing measurements of lightcurve features. Modelling RRL lightcurves will yield the lens orbital period and possibly measurements of all orbital elements including the inclination and eccentricity. Measurement of the period from the lightcurve allows a mass-distance relation to be defined, which when combined with a measurement of microlens parallax or finite source effects, can yield a mass measurement to a two-fold degeneracy. With sub-percent accuracy photometry it is possible to detect planetary companions, but the likelihood of this is very small.Comment: 16 pages, 14 figures, accepted for publication in MNRAS. Equation 21 simplifie

    Variation in dissolved organic matter (DOM) stoichiometry in UK freshwaters:Assessing the influence of land cover and soil C:N ratio on DOM composition

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    Dissolved organic matter (DOM) plays an important role in freshwater biogeochemistry. To investigate the influence of catchment character on the quality and quantity of DOM in freshwaters, forty-five sampling sites draining subcatchments of contrasting soil type, hydrology and land cover within one large upland-dominated and one large lowland-dominated catchment, were sampled over a one-year period. Dominant land cover in each subcatchment included: arable and horticultural, blanket peatland, coniferous woodland, improved-, unimproved-, acid- and calcareous-grasslands. The composition of the C, N, and P pool was determined as a function of the inorganic nutrient species (NO3-, NO2-, NH4+, PO43-) and dissolved organic nutrient (DOC, DON and DOP) concentrations. DOM quality was assessed by calculation of the molar DOC:DON and DOC:DOP ratios and specific ultraviolet absorbance (SUVA254). In catchments with little anthropogenic nutrient inputs, DON and DOP typically comprised >80% of the TDN and TDP concentrations. By contrast, in heavily impacted agricultural catchments DON and DOP typically comprised 5-15% of TDN and 10-25% of TDP concentrations. Significant differences in DOC:DON and DOC:DOP ratios were observed between land cover class with significant correlations observed between both the DOC:DON and DOC:DOP molar ratios and SUVA254 (rs = 0.88 and 0.84, respectively). Analysis also demonstrated a significant correlation between soil C:N ratio and instream DOC:DON/DOP (rs = 0.79 and 0.71 respectively). We infer from this that soil properties, specifically the C:N ratio of the soil organic matter pool, has a significant influence on the composition of DOM in streams draining through these landscapes

    Patients report improvements in continuity of care when quality of life assessments are used routinely in oncology practice: Secondary outcomes of a randomised controlled trial.

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    INTRODUCTION AND AIM: In a randomised trial investigating the effects of regular use of health-related quality of life (HRQOL) in oncology practice, we previously reported an improvement in communication (objective analysis of recorded encounters) and patient well-being. The secondary aims of the trial were to measure any impact on patient satisfaction and patients' perspectives on continuity and coordination of their care. METHODS: In a prospective trial involving 28 oncologists, 286 cancer patients were randomised to: (1) intervention arm: regular touch-screen completion of HRQOL with feedback to physicians; (2) attention-control arm: completion of HRQOL without feedback; and (3) control arm: no HRQOL assessment. Secondary outcomes were patients' experience of continuity of care (Medical Care Questionnaire, MCQ) including 'Communication', 'Coordination' and 'Preferences to see usual doctor' subscales, patients' satisfaction, and patients' and physicians' evaluation of the intervention. Analysis employed mixed-effects modelling, multiple regression and descriptive statistics. RESULTS: Patients in the intervention arm rated their continuity of care as better than the control group for 'Communication' subscale (p=0.03). No significant effects were found for 'Coordination' or 'Preferences to see usual doctor'. Patients' evaluation of the intervention was positive. More patients in the intervention group rated the HRQOL assessment as useful compared to the attention-control group (86% versus 29%), and reported their doctors considered daily activities, emotions and quality of life. CONCLUSION: Regular use of HRQOL measures in oncology practice brought changes to doctor-patient communication of sufficient magnitude and importance to be reported by patients. HRQOL data may improve care through facilitating rapport and building inter-personal relationships

    Land cover and nutrient enrichment regulates low-molecular weight dissolved organic matter turnover in freshwater ecosystems

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    Dissolved organic matter (DOM) is a complex mixture of carbon-containing compounds. The low-molecular weight (LMW) fraction constitutes thousands of different compounds and represents a substantial proportion of DOM in aquatic ecosystems. The turnover rates of this LMW DOM can be extremely high. Due to the challenges of measuring this pool at a molecular scale, comparatively little is known of the fate of LMW DOM compounds in lotic systems. This study addresses this knowledge gap, investigating the microbial processing of LMW DOM across 45 sites representing a range of physicochemical gradients and dominant land covers in the United Kingdom. Radioisotope tracers representing LMW dissolved organic carbon (DOC) (glucose), dissolved organic nitrogen (DON) (amino acid mixture), dissolved organic phosphorus (DOP) (glucose-6-phosphate), and soluble reactive phosphorus (SRP, measured as orthophosphate) were used to measure the microbial uptake of different DOM compounds in river waters. The amount of DOM biodegradation varied between different components (DON ≥ DOC > DOP), with the rate of turnover of all three increasing along a gradient of N and P enrichment across the range of sites. Conversely, the uptake of SRP decreased along this same gradient. This was ascribed to preferential utilization of DOP over SRP. Dominant land cover had a significant effect on DOM use as a resource, due to its control of nutrient enrichment within the catchments. We conclude that nutrient enrichment of river waters will lead to further DOM removal from the water column, increased microbial growth, and a decrease in stream oxygen saturation, exacerbating the effects of eutrophication in rivers

    Evolution and comparative analysis of the MHC Class III inflammatory region

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    BACKGROUND: The Major Histocompatibility Complex (MHC) is essential for immune function. Historically, it has been subdivided into three regions (Class I, II, and III), but a cluster of functionally related genes within the Class III region has also been referred to as the Class IV region or "inflammatory region". This group of genes is involved in the inflammatory response, and includes members of the tumour necrosis family. Here we report the sequencing, annotation and comparative analysis of a tammar wallaby BAC containing the inflammatory region. We also discuss the extent of sequence conservation across the entire region and identify elements conserved in evolution. RESULTS: Fourteen Class III genes from the tammar wallaby inflammatory region were characterised and compared to their orthologues in other vertebrates. The organisation and sequence of genes in the inflammatory region of both the wallaby and South American opossum are highly conserved compared to known genes from eutherian ("placental") mammals. Some minor differences separate the two marsupial species. Eight genes within the inflammatory region have remained tightly clustered for at least 360 million years, predating the divergence of the amphibian lineage. Analysis of sequence conservation identified 354 elements that are conserved. These range in size from 7 to 431 bases and cover 15.6% of the inflammatory region, representing approximately a 4-fold increase compared to the average for vertebrate genomes. About 5.5% of this conserved sequence is marsupial-specific, including three cases of marsupial-specific repeats. Highly Conserved Elements were also characterised. CONCLUSION: Using comparative analysis, we show that a cluster of MHC genes involved in inflammation, including TNF, LTA (or its putative teleost homolog TNF-N), APOM, and BAT3 have remained together for over 450 million years, predating the divergence of mammals from fish. The observed enrichment in conserved sequences within the inflammatory region suggests conservation at the transcriptional regulatory level, in addition to the functional level

    Stellar mass loss and the Intra-Cluster Medium in Galactic globular clusters: a deep radio survey for HI and OH

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    We present the results of a survey, the deepest to date, for HI emission at 21 cm and OH emission at 18 cm (lines at 1612, 1665, 1667 and 1720 MHz) in the direction towards the Galactic globular clusters M 15, M 2, NGC 6934, NGC 7006 and Pal 13. The aim is to measure the amount of hydrogen in the intra-cluster medium (ICM), and to find OH masers in the circumstellar envelopes of globular cluster red giants. We present a tentative detection of 0.3 Msun of neutral hydrogen in M 15 and possible detections of neutral hydrogen in M 2 and Pal 13. We derive upper limits to the neutral hydrogen content of NGC 6934 and NGC 7006. No OH emission is detected. We also present deep HI data of the northern tip of the Magellanic Stream behind Pal 13.Comment: Accepted for publication in MNRAS. 7 page
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