481 research outputs found
Elevated atmospheric CO<sub>2</sub> alters the multi-element stoichiometry of pollen-bearing oak flowers, with possible negative effects on bees
Increasing atmospheric CO2 levels change the elemental composition in plants, altering their nutritional quality and affecting consumers and ecosystems. Ecological stoichiometry provides a framework for investigating how CO2-driven nutrient dilution in pollen affects bees by linking changes in pollen chemical element proportions to the nutritional needs of bees. We investigated the consequences of five years of Free Air CO2 Enrichment (FACE) in a mature oak-dominated temperate forest on the elemental composition of English oak (Quercus robur) pollen. We measured the concentrations and proportions of 12 elements (C, N, P, S, K, Na, Ca, Mg, Cu, Zn, Fe, and Mn) in Q. robur pollen-bearing flowers collected from the Birmingham Institute for Forest Research (BIFoR) FACE facility. An elevated CO2 (eCO2) level of 150Â ppm above ambient significantly reduced the S, K, and Fe levels and altered the multi-element ratio, with different elements behaving differently. This shift in pollen multi-element composition may have subsequent cascading effects on higher trophic levels. To assess the impact on bees, we calculated the stoichiometric mismatch (a measure of the discrepancy between consumer needs and food quality) for two bee species, Osmia bicornis (red mason bee) and Apis mellifera (honey bee), that consume oak pollen in nature. We observed stoichiometric mismatches for P and S, in pollen under eCO2, which could negatively affect bees. We highlight the need for a comprehensive understanding of the changes in pollen multi-element stoichiometry under eCO2, which leads to nutrient limitations under climate change with consequences for bees.</p
Helminths associated with terrestrial slugs in some parts of Europe
A survey of helminths associated with terrestrial slugs focusing on the invasive Arion vulgaris and the native A. ater was conducted on populations from France, Germany, Netherlands, Norway and Poland. In total, 648 terrestrial slugs were collected from 18 sample sites, and identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. In addition to A. vulgaris and A. ater, also A. vulgaris/A. rufus hybrids and A. ater/A. rufus hybrids were collected. Helminth species were identified based on morphological features and sequencing of the 18S and ITS rDNA regions. The parasites included four nematode species: Alloionema appendiculatum, Angiostoma sp., Phasmarhabditis hermaphrodita, Entomelas sp., two trematode species: Brachylaima mesostoma, Eurytrema sp., and one cestode (tapeworm) species: Skrjabinia sp. Alloionema appendiculatum was the most common helminth in the investigated slug populations. Furthermore, we found higher prevalence of trematodes in the invasive A. vulgaris compared with the native A. ater, while differences in the prevalence for nematodes were not as clear.publishedVersio
The Carbon Monoxide Tape Recorder
Using Aura MLS data we have identified the stratospheric tape recorder in carbon monoxide (CO). Unlike the water vapor tape recorder, which is controlled by upper troposphere processes, the CO tape recorder is linked to seasonal biomass burning. Since CO has a lifetime of only a few months, the CO tape recorder barely extends above 20 km. The tape head for CO appears to be close to 360K near the same location as the water vapor tape head [Read et al, 20041. Both tape heads are below the equatorial cold point tropopause but above the base of the tropical tropopause layer. The tape recorder signal becomes more distinct from 360K to 380K suggesting that convective detrainment of plays a decreasingly important role with altitude. The Global Modeling Initiative chemical transport model forced by the climatology of biomass burning reproduces the CO tape recorder
Substituent position effects on sunscreen photodynamics : a closer look at methyl anthranilate
Towards the development of a bottom-up rationale for sunscreen design, the effects of substituent position on the ultrafast photodynamics of the sunscreen precursor methyl anthranilate (MA, an ortho compound) were evaluated by studying para- and meta-MA in vacuum. Time-resolved ion yield (TR-IY) measurements reveal a long-lived S1 excited state (≫ 1.2 ns) for para-MA, proposed to be the result of a weakly fluorescent, bound excited state. In the case of meta-MA, TR-IY transients reveal a much faster (∼2 ns) excited state relaxation, possibly due to multiple low-lying S1/S0 conical intersections of prefulvenic character. While meta-MA may not be an ideal sunscreen ingredient due to a low ultraviolet absorbance, its comparatively efficient relaxation mechanism may constitute an alternative to common sunscreen relaxation pathways. Thus, our results should prompt further studies of prefulvenic relaxation pathways in potential sunscreen agents
‘Give courage to the ladies’: expansive apprenticeship for women in rural Malawi
Apprenticeship in developed and industrialised nations is increasingly understood as a theory of learning which connects workplace activity and formal study. The concept of ‘expansive apprenticeship’ defines frameworks for workforce development where participants acquire knowledge and skills which will help them in the future as well as in their current roles, whilst ‘restrictive’ apprenticeships limit opportunities for wider, lifelong learning. In developing nations apprenticeship is a traditional route to learning and employment, but apprenticeships in these contexts tend to reflect a restrictive approach characterized by narrowly defined roles and weak educational outcomes. This paper examines a project in Malawi which uses concepts of expansive apprenticeship to address barriers to female continuing education and chronic teacher shortages. The Malawi Access to Teaching Scholarship recruited one thousand women to follow a year-long combined programme of academic distance study and practical work experience in rural primary schools. The aim is to increase the numbers of women teachers in Malawi, especially in rural areas. The Scholarship materials and support structures are designed to move participants from restrictive to expansive contexts for learning so that Scholars develop hybrid roles as students, community workers and apprentice pedagogues. The programme’s resources and approach offer an innovative model of expansive apprenticeship in Sub Saharan Africa
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