2,273 research outputs found

    Spatial connectedness imposes local‐ and metapopulation‐level selection on life history through feedbacks on demography

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    Dispersal evolution impacts the fluxes of individuals and hence, connectivity in metapopulations. Connectivity is therefore decoupled from the structural connectedness of the patches within the spatial network. Because of demographic feedbacks, local selection also drives the evolution of other life history traits. We investigated how different levels of connectedness affect trait evolution in experimental metapopulations of the two-spotted spider mite. We separated local- and metapopulation-level selection and linked trait divergence to population dynamics. With lower connectedness, an increased starvation resistance and delayed dispersal evolved. Reproductive performance evolved locally by transgenerational plasticity or epigenetic processes. Costs of dispersal, but also changes in local densities and temporal fluctuations herein are found to be putative drivers. In addition to dispersal, demographic traits are able to evolve in response to metapopulation connectedness at both the local and metapopulation level by genetic and/or non-genetic inheritance. These trait changes impact the persistence of spatially structured populations

    The Small RNA ErsA of Pseudomonas aeruginosa Contributes to Biofilm Development and Motility through Post-transcriptional Modulation of AmrZ

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    The small RNA ErsA of Pseudomonas aeruginosa was previously suggested to be involved in biofilm formation via negative post-transcriptional regulation of the algC gene that encodes the virulence-associated enzyme AlgC, which provides sugar precursors for the synthesis of several polysaccharides. In this study, we show that a knock-out ersA mutant strain forms a flat and uniform biofilm, not characterized by mushroom-multicellular structures typical of a mature biofilm. Conversely, the knock-out mutant strain showed enhanced swarming and twitching motilities. To assess the influence of ErsA on the P. aeruginosa transcriptome, we performed RNA-seq experiments comparing the knock-out mutant with the wild-type. More than 160 genes were found differentially expressed in the knock-out mutant. Parts of these genes, important for biofilm formation and motility regulation, are known to belong also to the AmrZ transcriptional regulator regulon. Here, we show that ErsA binds in vitro and positively regulates amrZ mRNA at post-transcriptional level in vivo suggesting an interesting contribution of the ErsA-amrZ mRNA interaction in biofilm development at several regulatory levels

    Quality of life of homosexual males with genital warts: a qualitative study

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    <p>Abstract</p> <p>Background</p> <p>A recent qualitative study in Denmark showed that genital warts (GWs) can considerably lower the quality of life of heterosexual patients. In this follow-up study, we interviewed men having sex with men (MSM) suffering from GWs to obtain an in-depth understanding of their perception of GWs and determine the extent to which minority (homosexual) cultural issues affect these patients' experiences. Qualitative interviews with six MSM were performed using a semi-structured interview guide. Questions were formulated on the basis of the earlier qualitative study in heterosexual patients with GWs along with a literature review. Data were analysed using a medical anthropological approach.</p> <p>Findings</p> <p>Many MSM worried about being stigmatised and excluded from the small homosexual <it>'scene'</it>, their key social group, thereby lowering their chances of finding sex and love. Most participants had suffered from GWs for several years which added to the negative psycho-sexual and social effects of the disease. Participants' fears of developing anal cancer were similar to those expressed about cervical cancer by females with GWs.</p> <p>Conclusions</p> <p>Ano-genital human papillomavirus (HPV) infection is common and has a serious psychological and sexual impact among MSM. However, they do not benefit to the same extent as heterosexual men from the herd immunity effect of HPV vaccination of girls. The pathological profile and concerns specific to MSM should be addressed when communicating with these patients, and should be taken into account when considering HPV vaccination of boys.</p

    Learning from crisis: the 2015 and 2017 avalanches in Longyearbyen

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    Longyearbyen has been hit by two avalanches in 2015 and 2017 causing severe damages to housing and two fatalities. In this study we investigate organised learning processes regarding emergency preparedness and response following the avalanches. Longyearbyen provides a case of particular interest as climatic change rapidly is altering the environmental conditions, including the risk of avalanches. First, the study outlines the organisation, scope and participation of learning processes, that is, who learns, when and what is the scope. Second we investigate whether the lessons learnt are single-loop or double-loop; if they focus on corrective actions of existing systems and policies, or if they address the more fundamental aspects, such as norms, strategies and policies. Third, we consider how contextual factors influence learning. Finally, we investigate how learning has been followed up by implementation. The study concludes that the first avalanche of 2015 led to a broad and inclusive evaluation and learning process and a series of recommended measures, including the establishment of an avalanche warning system. It also initiated a broader double-loop process of reassessing risks, redrawing the plans and maps of Longyearbyen, and raising physical preventive barriers. However, the second avalanche demonstrated the limitations of the established system in 2015. This spurred a range of corrective actions to the system, but also it established that in a time of climate change, historical experience no longer provides a basis for assessing risks

    Development of sampling efficiency and internal noise in motion detection and discrimination in school-aged children

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    AbstractThe aim of this study was to use an equivalent noise paradigm to investigate the development and maturation of motion perception, and how the underlying limitations of sampling efficiency and internal noise effect motion detection and direction discrimination in school-aged children (5–14years) and adults. Contrast energy thresholds of a 2c/deg sinusoidal grating drifting at 1.0 or 6.0Hz were measured as a function of added dynamic noise in three tasks: detection of a drifting grating; detection of the sum of two oppositely drifting gratings and direction discrimination of oppositely drifting gratings. Compared to the ideal observer, in both children and adults, the performance for all tasks was limited by reduced sampling efficiency and internal noise. However, the thresholds for discrimination of motion direction and detection of moving gratings show very different developmental profiles. Motion direction discrimination continues to improve after the age of 14years due to an increase in sampling efficiency that differs with speed. Motion detection and summation were already mature at the age of 5years, and internal noise was the same for all tasks. These findings were confirmed in a 1-year follow-up study on a group of children from the initial study. The results support suggestions that the detection of a moving pattern and discriminating motion direction are processed by different systems that may develop at different rates

    Palmitoylation of the luteinizing hormone/human chorionic gonadotropin receptor regulates receptor interaction with the arrestin-mediated internalization pathway

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65516/1/j.1432-1327.2001.02032.x.pd

    Participation and error rates of the Internal Revenue Service Electronic Filing System : empirical evidence and implementation lessons.

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    The process of collecting revenue has become increasingly costly for the Internal Revenue Service (IRS) in terms of requirements for storage space and the complexity and time involved in converting paper returns into machine readable form. To alleviate these problems, the IRS proposed and developed the Electronic Filing System (EFS) which provides taxpayers the option of filing tax returns electronically. This study consists of a two year field study of the EFS in the San Jose District with respect to the reasons for success or failure of the implementation of computer systems, with particular emphasis on the participation rate and the error rate. The study includes a statistical analysis of responses to two surveys distributed by the San Jose District EFS Office to determine whether there is significant evidence to indicate reasons why some users have higher error rates than others. A case study approach is used, in conjunction with available literature, to determine factors which influence the effective implementation of an information system and encourage use of the system.http://archive.org/details/participationerr00elliLieutenant, United States NavyApproved for public release; distribution is unlimited

    Brain glycogen—new perspectives on its metabolic function and regulation at the subcellular level

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    Glycogen is a complex glucose polymer found in a variety of tissues, including brain, where it is localized primarily in astrocytes. The small quantity found in brain compared to e.g., liver has led to the understanding that brain glycogen is merely used during hypoglycemia or ischemia. In this review evidence is brought forward highlighting what has been an emerging understanding in brain energy metabolism: that glycogen is more than just a convenient way to store energy for use in emergencies—it is a highly dynamic molecule with versatile implications in brain function, i.e., synaptic activity and memory formation. In line with the great spatiotemporal complexity of the brain and thereof derived focus on the basis for ensuring the availability of the right amount of energy at the right time and place, we here encourage a closer look into the molecular and subcellular mechanisms underlying glycogen metabolism. Based on (1) the compartmentation of the interconnected second messenger pathways controlling glycogen metabolism (calcium and cAMP), (2) alterations in the subcellular location of glycogen-associated enzymes and proteins induced by the metabolic status and (3) a sequential component in the intermolecular mechanisms of glycogen metabolism, we suggest that glycogen metabolism in astrocytes is compartmentalized at the subcellular level. As a consequence, the meaning and importance of conventional terms used to describe glycogen metabolism (e.g., turnover) is challenged. Overall, this review represents an overview of contemporary knowledge about brain glycogen and its metabolism and function. However, it also has a sharp focus on what we do not know, which is perhaps even more important for the future quest of uncovering the roles of glycogen in brain physiology and pathology

    Plant Biomarker Pattern, Apples grown with various availability of organic nitrogen and with or witout the use of pesticides

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    In the recent years there has been an increasing focus on the quality and health value of organic plant products compared with conventional products. The use of pesticides and concentrated fertilisers in conventional agriculture implies a risk of effects on plant composition, which may affect health of the consumer (Brandt & Mølgaard, 2001). To determine if organically grown plant food could provide more or less benefits to health than conventional food, a first step is to investigate the differences in the composition and relative concentration of natural compounds in the plant products. In this project apples were grown with two levels of nitrogen availability and with or without the use of pesticides. The apples were screened for changes in the phytochemical composition and concentration. The work is affiliated to the project "Organic food and health" supported by the Danish Research Centre for Organic Farming (DARCOF). Biomarkers and biomarker patterns were presented in plants cultivated with low and high N and with pesticides. One biomarker was related to: • the type of N with and without pesticides • pesticides at high N and type of N without pesticides • pesticides at low and high N One biomarker pattern was related to: • the type of N • the type of N without pesticides • pesticides at low N and type of N without pesticides • pesticides at high N and type of N with pesticide
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