Long-term development of reservoir ecosystems - changes in pelagic food webs and their microbial component

Reservoirs differ from lakes mostly in three aspects: (i) water residence times usually are not longer than several months, (ii) horizontal heterogeneity induced by the inflowing river water is more pronounced, and (iii) they are historically much younger than lakes. As a consequence, seasonal and long-term dynamics of pelagic food webs reflect the changes in the catchment and hydrological variations more significantly than in lakes, and an ageing and "maturing" of the reservoir ecosystem might affect the pelagic biomass even several decades after filling. Using long-term data sets on pelagic biomass components from canyonshaped reservoirs of different residence time, the following topics are discussed: (1) changes of pelagic bacteria-phytoplankton - zooplankton abundances during ageing as well as longitudinal changes from the river inflow dowstream to the lacustrine part of a reservoir, (2) long-term changes of pelagic bacteria-phytoplankton-zooplankton abundances and seasonal changes of microbial loop in two reservoirs of different residence times. Periods with relative prevalence of bacterial above zooplankton biomass were detected, mostly coinciding with (or following after) the periods with low phytoplankton to zooplankton ratios.Los embalses difieren de los lagos principalmente en tres aspectos: (i) el tiempo de residencia del agua no suele ser superior a varios meses, (ii) la heterogeneidad horizontal inducida por la entrada de agua fluvial es más marcada, y (iii) son históricamente mucho más jóvenes que los lagos. Como consecuencia de todo ello, las dinámicas estacional y a largo plazo de las redes tróficas pelágicas reflejan los cambios en la cuenca y las variaciones hidrológicas más significativamente que en los lagos, y el envejecimiento y "madurez" del ecosistema del embalse podría afectar a la biomasa pelágica incluso varias décadas después de su llenado. Mediante el análisis de largas series de datos sobre la biomasa de componentes pelágicos en embalses con sección en forma de cañón y diferentes tiempos de residencia, se discuten los siguientes aspectos: (1) cambios en las abundancias de bacterias-fitoplancton-zooplancton pelágicos durante el envejecimiento del embalse, así como cambios longitudinales desde la entrada de los ríos hasta la zona lacustre del embalse, (2) cambios a largo plazo en las abundancias de bacterias-fitoplancton-zooplancton pelágicos y cambios estacionales del bucle microbiano en dos embalses con diferentes tiempos de residencia. Se detectaron períodos con un predominio relativo de la biomasa bacteriana sobre la biomasa de zooplancton, coincidiendo principalmente con (o justamente después de) los períodos con bajas relaciones fitoplancton / zooplancton

Community structure, picoplankton grazing and zooplankton control of heterotrophic nanoflagellates in a eutrophic reservoir during the summer phytoplankton maximum

An intensive 5 wk study was conducted to investigate the role of protists, especially heterotrophic nanoflagellates (HNF), in microbial food webs during the summer phytoplankton bloom in the epilimnion and metalimnion of the eutrophic Rimov reservoir (South Bohemia, Czech Republic). On average, protists consumed similar to 90% of bacterial production in both layers. The community composition of HNF and the relative importance of different HNF groups as picoplankton consumers were determined. Small HNF (<8 mu m), as chrysomonads, bodonids and choanoflagellates, usually accounted for <30% of total HNF biomass but numerically dominated the community in both layers. They consumed most of (similar to 70 to 85 %) the bacterioplankton as well as autotrophic picoplankton (APP, exclusively cyanobacteria) production in the reservoir, with the rest consumed by ciliates. Both ciliates and HNF had higher clearance rates on APP than on bacteria and their grazing was likely responsible for a sharp decrease in APP abundance (from 3-4 x 10(5) to <2 x 10(3) ml(-1)) and a very constant size structure of bacterioplankton in which short rods in the size class of 0.4 to 0.8 mu m constituted 55 to 80 % of the total bacterial biomass in both layers. The proportion of HNF to total picoplankton biomass in the epilimnion indicated that the picoplankton biomass was sufficiently high to support HNF growth for most of the study. Uptake of picoplankton by less numerous, but larger, HNF (kathablepharids, Goniomonas sp., and Streptomonas sp.) was negligible, while their biomass, especially in the metalimnion, exceeded that of small HNF and the total biomass of picoplankton. This suggested that food items other than picoplankton were consumed to meet their carbon requirements. Analyzing potential bottom-up and top-down factors controlling HNF numbers and biomass, we did not find a tight relationship between HNF and the concentration of bacteria and chlorophyll. Variability of HNF abundance and biomass in the epilimnion could largely be explained by cladocerans or by pooled abundances of all potential crustacean consumers of HNF. In the metalimnion, the mean cell volume of HNF was positively linked to chlorophyll but negatively to the abundance of Cyclopidae and to the pooled abundances of Ceriodaphnia quadrangula and Diaphanosoma brachyurum

Online interventions to prevent mental health problems implemented in school settings: the perspectives from key stakeholders in Austria and Spain

Background: Schools are key settings for delivering mental illness prevention in adolescents. Data on stakeholders’ attitudes and factors relevant for the implementation of Internet-based prevention programmes are scarce. Methods: Stakeholders in the school setting from Austria and Spain were consulted. Potential facilitators (e.g. teachers and school psychologists) completed an online questionnaire (N=50), policy makers (e.g. representatives of the ministry of education and health professional associations) participated in semi-structured interviews (N=9) and pupils (N=29, 14–19 years) participated in focus groups. Thematic analysis was used to identify experiences with, attitudes and needs towards Internet-based prevention programmes, underserved groups, as well as barriers and facilitators for reach, adoption, implementation and maintenance. Results: Experiences with Internet-based prevention programmes were low across all stakeholder groups. Better reach of the target groups was seen as main advantage whereas lack of personal contact, privacy concerns, risk for misuse and potential stigmatization when implemented during school hours were regarded as disadvantages. Relevant needs towards Internet-based programmes involved attributes of the development process, general requirements for safety and performance, presentation of content, media/tools and contact options of online programmes. Positive attitudes of school staff, low effort for schools and compatibility to schools’ curriculum were seen as key factors for successful adoption and implementation. A sound implementation of the programme in the school routine and continued improvement could facilitate maintenance of online prevention initiatives in schools. Conclusions: Attitudes towards Internet-based mental illness prevention programmes in school settings are positive across all stakeholder groups. However, especially safety concerns have to be considered

RESPOND – A patient-centred program to prevent secondary falls in older people presenting to the emergency department with a fall: Protocol for a multi-centre randomised controlled trial

Introduction: Participation in falls prevention activities by older people following presentation to the Emergency Department (ED) with a fall is suboptimal. This randomised controlled trial (RCT) will test the RESPOND program which is designed to improve older persons’ participation in falls prevention activities through delivery of patient-centred education and behaviour change strategies. Design and setting: An RCT at two tertiary referral EDs in Melbourne and Perth, Australia. Participants: Five-hundred and twenty eight community-dwelling people aged 60-90 years presenting to the ED with a fall and discharged home will be recruited. People who: require an interpreter or hands-on assistance to walk; live in residential aged care or >50 kilometres from the trial hospital; have terminal illness, cognitive impairment, documented aggressive behaviour or history of psychosis; are receiving palliative care; or are unable to use a telephone will be excluded. Methods: Participants will be randomly allocated to the RESPOND intervention or standard care control group. RESPOND incorporates: (1) home-based risk factor assessment; (2) education, coaching, goal setting, and follow-up telephone support for management of one or more of four risk factors with evidence of effective intervention; and (3) healthcare provider communication and community linkage delivered over six months. Primary outcomes are falls and fall injuries per-person-year. Discussion: RESPOND builds on prior falls prevention learnings and aims to help individuals make guided decisions about how they will manage their falls risk. Patient-centred models have been successfully trialled in chronic and cardiovascular disease however evidence to support this approach in falls prevention is limited. Trial registration. The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000336684)

Risk assessment of the retrieval of transuranic waste: Pads 1, 2, and 4, Technical Area-54, Area G, Los Alamos National Laboratory

The Risk Assessment for the Retrieval of Transuranic Waste is a comparative risk assessment of the potential adverse human health effects resulting from exposure to contaminants during retrieval and post-retrieval aboveground storage operations of post-1970 earthen-covered transuranic waste. Two alternatives are compared: (1) Immediate Retrieval and (2) Delayed Retrieval. Under the Immediate Retrieval Alternative, retrieval of the waste is assumed to begin immediately, Under the Delayed Retrieval Alternative, retrieval is delayed 10 years. The current risk assessment is on Pads 1, 2, and 4, at Technical Area-54, Area-G, Los Alamos National Laboratory (LANL). Risks are assessed independently for three scenarios: (1) incident-free retrieval operations, (2) incident-free storage operations, and (3) a drum failure analysis. The drum failure analysis evaluates container integrity under both alternatives and assesses the impacts of potential drum failures during retrieval operations. Risks associated with a series of drum failures are potentially severe for workers, off-site receptors, and general on-site employees if retrieval is delayed 10 years and administrative and engineering controls remain constant. Under the Delayed Retrieval Alternative, an average of 300 drums out of 16,647 are estimated to fail during retrieval operations due to general corrosion, while minimal drums are predicted to fail under the Immediate Retrieval Alternative. The results of the current study suggest that, based on risk, remediation of Pads 1, 2, and 4 at LANL should not be delayed. Although risks from incident-free operations in the Delayed Retrieval Alternative are low, risks due to corrosion and drum failures are potentially severe

Is the use of videotape recording superior to verbal feedback alone in the teaching of clinical skills?

<p>Abstract</p> <p>Background</p> <p>In recent times, medical schools have committed to developing good communication and history taking skills in students. However, there remains an unresolved question as to which constitutes the best educational method. Our study aims to investigate whether the use of videotape recording is superior to verbal feedback alone in the teaching of clinical skills and the role of student self-assessment on history taking and communication skills.</p> <p>Methods</p> <p>A randomized controlled trial was designed. The study was conducted with 52 of the Dokuz Eylul University Faculty of Medicine second year students. All students' performances of communication and history taking skills were assessed twice. Between these assessments, the study group had received both verbal and visual feedback by watching their video recordings on patient interview; the control group received only verbal feedback from the teacher.</p> <p>Results</p> <p>Although the self-assessment of the students did not change significantly, assessors' ratings increased significantly for videotaped interviews at the second time.</p> <p>Conclusions</p> <p>Feedback based on videotaped interviews is superior to the feedback given solely based on the observation of assessors.</p

Catchment-scale biogeography of riverine bacterioplankton

Lotic ecosystems such as rivers and streams are unique in that they represent a continuum of both space and time during the transition from headwaters to the river mouth. As microbes have very different controls over their ecology, distribution and dispersion compared with macrobiota, we wished to explore biogeographical patterns within a river catchment and uncover the major drivers structuring bacterioplankton communities. Water samples collected across the River Thames Basin, UK, covering the transition from headwater tributaries to the lower reaches of the main river channel were characterised using 16S rRNA gene pyrosequencing. This approach revealed an ecological succession in the bacterial community composition along the river continuum, moving from a community dominated by Bacteroidetes in the headwaters to Actinobacteria-dominated downstream. Location of the sampling point in the river network (measured as the cumulative water channel distance upstream) was found to be the most predictive spatial feature; inferring that ecological processes pertaining to temporal community succession are of prime importance in driving the assemblages of riverine bacterioplankton communities. A decrease in bacterial activity rates and an increase in the abundance of low nucleic acid bacteria relative to high nucleic acid bacteria were found to correspond with these downstream changes in community structure, suggesting corresponding functional changes. Our findings show that bacterial communities across the Thames basin exhibit an ecological succession along the river continuum, and that this is primarily driven by water residence time rather than the physiochemical status of the river

A Limited Number of Antibody Specificities Mediate Broad and Potent Serum Neutralization in Selected HIV-1 Infected Individuals

A protective vaccine against HIV-1 will likely require the elicitation of a broadly neutralizing antibody (bNAb) response. Although the development of an immunogen that elicits such antibodies remains elusive, a proportion of HIV-1 infected individuals evolve broadly neutralizing serum responses over time, demonstrating that the human immune system can recognize and generate NAbs to conserved epitopes on the virus. Understanding the specificities that mediate broad neutralization will provide insight into which epitopes should be targeted for immunogen design and aid in the isolation of broadly neutralizing monoclonal antibodies from these donors. Here, we have used a number of new and established technologies to map the bNAb specificities in the sera of 19 donors who exhibit among the most potent cross-clade serum neutralizing activities observed to date. The results suggest that broad and potent serum neutralization arises in most donors through a limited number of specificities (1–2 per donor). The major targets recognized are an epitope defined by the bNAbs PG9 and PG16 that is associated with conserved regions of the V1, V2 and V3 loops, an epitope overlapping the CD4 binding site and possibly the coreceptor binding site, an epitope sensitive to a loss of the glycan at N332 and distinct from that recognized by the bNAb 2G12 and an epitope sensitive to an I165A substitution. In approximately half of the donors, key N-linked glycans were critical for expression of the epitopes recognized by the bNAb specificities in the sera