386 research outputs found

    Testing mechanisms of Bergmann’s rule: Phenotypic decline but no genetic change in body size in three posserine bird populations

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    Bergmann’s rule predicts a decrease in body size with increasing temperature and has much empirical support. Surprisingly, we know very little about whether “Bergmann size clines” are due to a genetic response or are a consequence of phenotypic plasticity. Here, we use data on body size (mass and tarsus length) from three long-term (1979–2008) study populations of great tits (Parus major) that experienced a temperature increase to examine mechanisms behind Bergmann’s rule. We show that adult body mass decreased over the study period in all populations and that tarsus length increased in one population. Both body mass and tarsus length were heritable and under weak positive directional selection, predicting an increase, rather than a decrease, in body mass. There was no support for microevolutionary change, and thus the observed declines in body mass were likely a result of phenotypic plasticity. Interestingly, this plasticity was not in direct response to temperature changes but seemed to be due to changes in prey dynamics. Our results caution against interpreting recent phenotypic body size declines as adaptive evolutionary responses to temperature changes and highlight the importance of considering alternative environmental factors when testing size clines.

    Translational and rotational motions of albumin sensed by a non-covalent associated porphyrin under physiological and acidic conditions: a fluorescence correlation spectroscopy and time resolved anisotropy study.

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    The interaction between a free-base, anionic water-soluble porphyrin, TSPP, and the drug carrier protein, bovine serum albumin (BSA) has been studied by time-resolved fluorescence anisotropy (TRFA) and fluorescence correlation spectroscopy (FCS) at two different pH-values. Both rotational correlation times and translational diffusion times of the fluorescent species indicate that TSPP binding to albumin induces very little conformational changes in the protein under physiological conditions. By contrast, at low pH, a bi-exponential decay is obtained where a short rotational correlation time (Âż intÂż=Âż1.2 ns) is obtained, which is likely associated to wobbling movement of the porphyrin in the protein binding site. These physical changes are corroborated by circular dichroism (CD) data which show a 37% loss in the protein helicity upon acidification of the medium. In the presence of excess porphyrin formation of porphyrin J-aggregates is induced, which can be detected by time-resolved fluorescence with short characteristic times. This is also reflected in FCS data by an increase in molecular brightness together with a decrease in the number of fluorescent molecules passing through the detection volume of the sampl

    Demand Driven Education: Report on the Education Innovation Project 'Design in Land and Water Management in a Demand Driven Learning Environment'

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    In the fifth period of the academic year 2008/2009 the chair groups Irrigation and Water Engineering (IWE) and Land Degradation and Development (LDD) organized a new course, i.e. Design in Land and Water Management 2 (IWE- 21312). The course is part of the BSc program International Land and Water Management (BIL). The decision to develop the course can be seen as a measure to ensure that BIL-graduates understand, can analyze, and are able to engage in and to advise on typical design processes as part of their professional practice as irrigation and soil- and water conservation experts

    Wind and rain interaction in erosion

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    The Effect of Negative-Energy Shells on the Schwarzschild Black Hole

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    We construct Penrose diagrams for Schwarzschild spacetimes joined by massless shells of matter, in the process correcting minor flaws in the similar diagrams drawn by Dray and 't Hooft, and confirming their result that such shells generate a horizon shift. We then consider shells with negative energy density, showing that the horizon shift in this case allows for travel between the heretofore causally separated exterior regions of the Schwarzschild geometry. These drawing techniques are then used to investigate the properties of successive shells, joining multiple Schwarzschild regions. Again, the presence of negative-energy shells leads to a causal connection between the exterior regions, even in (some) cases with two successive shells of equal but opposite total energy.Comment: 12 pages, 10 figure

    Managing behavioural symptoms of dementia : Effectiveness of staff education and peer support

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    This study was designed to investigate the impact of staff education on the behaviour and quality of life of residents with dementia and on staff members\u27 attitudes about working with people with dementia and level of burnout. Staff from three aged care facilities participated in the study (n = 52). These facilities were randomly assigned to one of two intervention groups or a control group. Staff assigned to the intervention groups received an eight-week behaviourally-based programme. Staff from one aged care facility also participated in a peer support group designed to reinforce educational material and facilitate positive changes among staff members. Behavioural symptoms displayed by residents (n = 76) in each of the facilities were also assessed. Assessments were conducted at pre-intervention, post-intervention, three- and six-month follow-up. The results of this study indicated that education or peer support was not associated with an improvement in resident behaviour or quality of life. Education or peer support also did not impact on staff members\u27 level of burnout. There was, however, a change in staff members\u27 attitudes about working with people with dementia. Possible explanations for these findings and implication for further research are considered. <br /

    Evidence for a Quantum Hall Insulator in an InGaAs/InP Heterostructure

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    We study the quantum critical behavior of the plateau-insulator (PI) transition in a low mobility InGaAs/InP heterostructure. By reversing the direction of the magnetic field (B) we find an averaged Hall resistance \rho_xy which remains quantized at the plateau value h/e^2 throughout the PI transition. We extract a critical exponent \kappa'= 0.57 +/- 0.02 for the PI transition which is slightly different from (and possibly more accurate than) the established value 0.42 +/- 0.04 as previously obtained from the plateau-plateau (PP) transitions.Comment: 3pages, 2 figures; submitted to EP2DS-14 conference proceeding

    Provenancing Flower Bulbs by Analytical Fingerprinting: Convallaria Majalis

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    The origin of agricultural products is gaining in appreciation while often hard to determine for various reasons. Geographical origin may be resolved using a combination of chemical and physical analytical technologies. In the present case of Lily of the Valley (Convallaria majalis) rhizomes, we investigated an exploratory set of material from The Netherlands, three other European (EU) countries and China. We show that the geographical origin is correlated to patterns of stable isotope ratios (isotope fingerprints) and volatile organic carbon (VOC) compounds (chemical fingerprints). These fingerprints allowed clear distinction using exploratory and supervised statistics. Isotope ratio mass spectrometry of 12C/13C, 14N/15N and 16O/18O isotopes separated materials from Europe and China successfully. The VOC patterns measured by Proton Transfer Reaction Mass Spectrometry (PTR-MS) allowed distinction of three groups: material from The Netherlands, the other EU countries and China. This knowledge is expected to help developing a systematic and efficient analytical tool for authenticating the origin of flower bulbs

    Route towards the ideal thresholdless laser

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    Quantum Matter and Optic

    The use of stakeholder analysis in integrated watershed management

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    In the Ngenge watershed, at Mt. Elgon in the eastern Ugandan highlands, agricultural practices cause serious soil erosion problems and subsequent decrease in soil and water quality. Attempts to manage soil erosion through policy interventions have not been successful, because existing policies and legislation for natural resource management are inadequate and often formulated without consulting local communities. In the Ngenge watershed, an integrated watershed management (IWM) program was initiated to foster sustainable land and water management solutions. Experience shows that successes in IWM programs depend on effective participation by all relevant groups of stakeholders. The present study investigates the usability of a stakeholder analysis (SA) and how it has to be linked with participatory problem identification and participatory formulation of action and work plans to build a base for effective IWM. The SA considered the following criteria: (1) stakeholders' commitment to implement IWM, (2) their power to influence policy-making and implementation processes, and (3) the expected impact of the IWM program on the stakeholders. The SA allowed identification of key groups of stakeholders who participated in workshops and jointly developed concrete action and work plans. These workshop outputs, together with the positive feedback of the stakeholders and the commitment of policy-makers to continue the process, are good indicators that SA is a useful means for supporting the development of IWM strategies
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