Soil organic carbon and root distribution in a temperate arable agroforestry system

Aim To determine, for arable land in a temperate area, the effect of tree establishment and intercropping treatments, on the distribution of roots and soil organic carbon to a depth of 1.5 m. Methods A poplar (Populus sp.) silvoarable agroforestry experiment including arable controls was established on arable land in lowland England in 1992. The trees were intercropped with an arable rotation or bare fallow for the first 11 years, thereafter grass was allowed to establish. Coarse and fine root distributions (to depths of up to 1.5 m and up to 5 m from the trees) were measured in 1996, 2003, and 2011. The amount and type of soil carbon to 1.5 m depth was also measured in 2011. Results The trees, initially surrounded by arable crops rather than fallow, had a deeper coarse root distribution with less lateral expansion. In 2011, the combined length of tree and understorey vegetation roots was greater in the agroforestry treatments than the control, at depths below 0.9 m. Between 0 and 1.5 m depth, the fine root carbon in the agroforestry treatment (2.56 t ha-1) was 79% greater than that in the control (1.43 t ha-1). Although the soil organic carbon in the top 0.6 m under the trees (161 t C ha-1) was greater than in the control (142 t C ha-1), a tendency for smaller soil carbon levels beneath the trees at lower depths, meant that there was no overall tree effect when a 1.5 m soil depth was considered. From a limited sample, there was no tree effect on the proportion of recalcitrant soil organic carbon. Conclusions The observed decline in soil carbon beneath the trees at soil depths greater than 60 cm, if observed elsewhere, has important implication for assessments of the role of afforestation and agroforestry in sequestering carbon

Soil carbon changes after establishing woodland and agroforestry trees in a grazed pasture

This study determined the effect of two tree planting methods (woodland and a silvopastoral agroforestry system) on the soil bulk density and organic carbon content of a grassland site in lowland England. Soil organic carbon was measured in pasture, silvopastoral tree, and woodland treatments at six depths representative of 0–150 cm. Fourteen years after tree planting, the organic carbon content in the surface soil layer (0–10 cm) was greatest in the pasture (6.0 g 100 g− 1) and least in the woodland (4.6 g 100 g− 1); the value (5.3 g 100 g− 1) below the silvopastoral trees was intermediate. In the 10–20 cm layer, the organic carbon content in the woodland was 13% lower than the pasture. No treatment effects on soil carbon were detected below 20 cm. Possible reasons for the decline in surface soil carbon include a decline in grass cover and reduced soil water content. Measurements of above ground carbon storage by the trees indicated that tree planting increased overall carbon storage, with the silvopastoral system predicted to achieve a higher level of carbon storage than equivalent areas of separate woodland and pasture. A power analysis indicates that a prohibitively large number of replicates is needed to ensure a lower than 20% risk of falsely concluding no treatment differences at individual depth increments below 10 cm and cumulative depths extending below 40 cm

Sunfleck properties from time series of fluctuating light

Light in canopies is highly dynamic since the strength and composition of incoming radiation is determined by the wind and the Sun's trajectory and by canopy structure. For this highly dynamic environment, we mathematically defined sunflecks as periods of high irradiance relative to the background light environment. They can account for a large proportion of the light available for photosynthesis. Based on high-frequency irradiance measurements with a CCD array spectroradiometer, we investigated how the frequency of measurement affects what we define as sunflecks. Do different plant canopies produce sunflecks with different properties? How does the spectral composition and strength of irradiance in the shade vary during a sunfleck? Our results suggest that high-frequency measurements improved our description of light fluctuations and led to the detection of shorter, more frequent and intense sunflecks. We found that shorter wind-induced sunflecks contribute most of the irradiance attributable to sunflecks, contrary to previous reports from both forests and crops. Large variations in sunfleck properties related to canopy depth and species, including distinct spectral composition under shade and sunflecks, suggest that mapping canopy structural traits may help us model photosynthesis dynamically.Peer reviewe

Atom chips on direct bonded copper substrates

We present the use of direct bonded copper (DBC) for the straightforward fabrication of high power atom chips. Atom chips using DBC have several benefits: excellent copper/substrate adhesion, high purity, thick (> 100 microns) copper layers, high substrate thermal conductivity, high aspect ratio wires, the potential for rapid (< 8 hr) fabrication, and three dimensional atom chip structures. Two mask options for DBC atom chip fabrication are presented, as well as two methods for etching wire patterns into the copper layer. The wire aspect ratio that optimizes the magnetic field gradient as a function of power dissipation is determined to be 0.84:1 (height:width). The optimal wire thickness as a function of magnetic trapping height is also determined. A test chip, able to support 100 A of current for 2 s without failing, is used to determine the thermal impedance of the DBC. An assembly using two DBC atom chips to provide magnetic confinement is also shown.Comment: 8 pages, 5 figure

Brane Gas Inflation

We consider the brane gas picture of the early universe. At later stages, when there are no winding modes and the background is free to expand, we show that a moving 3-brane, which we identify with our universe, can inflate even though it is radiation-dominated. The crucial ingredients for successful inflation are the coupling to the dilaton and the equation of state of the bulk. If we suppose the brane initially forms in a collision of higher-dimensional branes, then the spectrum of primordial density fluctuations naturally has a thermal origin.Comment: 4 pages, 1 figur

Rapid kinetics of changes in oxygen consumption rate in thrombin-stimulated platelets measured by high-resolution respirometry.

Platelet activation plays a key role in normal haemostasis and pathological thrombosis. Platelet activation is rapid; within minutes of stimulation, platelets generate bioactive phospholipids, secrete their granule contents, activate integrins and aggregate together to form a haemostatic plug. These events are dependent on ATP synthesis. Mitochondrial function in platelets from healthy volunteers and patients with a range of diseases indicate an important role for oxygen consumption in oxidative phosphorylation in normal and pathological function. Platelets also consume oxygen during oxidation reactions, such as cyclooxygenase-dependent thromboxane A2 synthesis. In this study, we used high-resolution respirometry to investigate rapid changes in oxygen consumption during platelet activation. We demonstrated a rapid, transient increase in oxygen consumption rate within minutes of platelet stimulation by the physiological activator, thrombin. This was partly inhibited by aspirin and by oligomycin. This shows that high resolution respirometry can provide information regarding rapid and dynamic changes in oxygen consumption during platelet activation

Choose Your Own Adventure: The Hero\u27s Journey and the Research Process

In Joseph Campbell’s Hero’s Journey, the hero of the story embarks on an adventure and returns transformed, empowered, and enlightened. Two academic librarians and the research process itself were incorporated into the curriculum of an undergraduate composition course that was structured around the research and writing process as a hero’s journey. The experience, which was student/hero-centered, self-directed, self-defined, investigative, and exploratory, was transformative for the students and the librarians as well

Posterior segment eye disease in sub-Saharan Africa: review of recent population-based studies.

OBJECTIVE: To assess the burden of posterior segment eye diseases (PSEDs) in sub-Saharan Africa (SSA). METHODS: We reviewed published population-based data from SSA and other relevant populations on the leading PSED, specifically glaucoma, diabetic retinopathy and age-related macular degeneration, as causes of blindness and visual impairment in adults. Data were extracted from population-based studies conducted in SSA and elsewhere where relevant. RESULTS: PSEDs, when grouped or as individual diseases, are a major contributor to blindness and visual impairment in SSA. PSED, grouped together, was usually the second leading cause of blindness after cataract, ranging as a proportion of blindness from 13 to 37%. CONCLUSIONS: PSEDs are likely to grow in importance as causes of visual impairment and blindness in SSA in the coming years as populations grow, age and become more urban in lifestyle. African-based cohort studies are required to help estimate present and future needs and plan services to prevent avoidable blindness

Ancestral light and chloroplast regulation form the foundations for C4 gene expression.

C4 photosynthesis acts as a carbon concentrating mechanism that leads to large increases in photosynthetic efficiency. The C4 pathway is found in more than 60 plant lineages1 but the molecular enablers of this evolution are poorly understood. In particular, it is unclear how non-photosynthetic proteins in the ancestral C3 system have repeatedly become strongly expressed and integrated into photosynthesis gene regulatory networks in C4 leaves. Here, we provide clear evidence that in C3 leaves, genes encoding key enzymes of the C4 pathway are already co-regulated with photosynthesis genes and are controlled by both light and chloroplast-to-nucleus signalling. In C4 leaves this regulation becomes increasingly dependent on the chloroplast. We propose that regulation of C4 cycle genes by light and the chloroplast in the ancestral C3 state has facilitated the repeated evolution of the complex and convergent C4 trait.The work was funded by the European Union 3to4 project and Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/J011754/1. I.G.-M. was supported by the Amgen Foundation. Research on chloroplast signalling by M.J.T. was supported by BBSRC grant (BB/J018139/1).This is the author accepted manuscript. The final version is available from the Nature Publishing Group via http://dx.doi.org/10.1038/nplants.2016.16

The Relationship Between Race, Patient Activation, and Working Alliance: Implications for Patient Engagement in Mental Health Care

This study explored the relationship between race and two key aspects of patient engagement—patient activation and working alliance—among a sample of African-American and White veterans (N = 152) seeking medication management for mental health conditions. After adjusting for demographics, race was significantly associated with patient activation, working alliance, and medication adherence scores. Patient activation was also associated with working alliance. These results provide support for the consideration of race and ethnicity in facilitating patient engagement and patient activation in mental healthcare. Minority patients may benefit from targeted efforts to improve their active engagement in mental healthcare