5,147 research outputs found
Quantifying the FIR interaction enhancement in paired galaxies
The Catalog of Isolated Pairs of Galaxies in the Northern Hemisphere, by Karachentsev (1972), was studied and a well-matched comparison sample taken from the Catalog of Isolated Galaxies, by Karachentseva (1973), in order to quantify the enhanced FIR emission properties of interacting galaxies
Can managed grasslands enhance pollinators in intensively farmed areas?
Wild flower strips is a common agri-environmental scheme used by farmers and land managers in order to improve biodiversity of pollinators. However, managed grasslands may also provide flower resources for flower visiting insects in agricultural landscapes. Botanically diverse grasslands on arable farms may support a range of wild pollinators, enhancing pollination services of crops. Intensively managed leys, on the other hand, typically contain only a few high-yielding, competitively strong species.
One of the aims of the Multiplant project (2014-2018) was to test perennial seed mixtures targeted for bio-energy, feed protein and biodiversity, in order to develop multi-functional seed mixtures for grasslands. In the current study, we specifically investigated if yield (biomass production) and floral resources for pollinators could be simultaneously optimized by varying botanical composition of mixtures and cutting frequency. We tested four different perennial seed mixtures (3-, 5-, 11- and 13-species mixtures) at three sites varying in surrounding environment using three cutting strategies (no cutting, two cuts per year, four cuts per year). We measured flower production during the season, composition of flower-visitors (in functional groups), and biomass production of all plant species in the seed mixtures.
The 11- and 13-species mixtures, which were designed to enhance pollinators, produced similar or higher yield than the 3- and 5- species mixtures under certain cutting regimes. The 3- and 5- species mixtures had a high accumulated flower abundance due to excessive flowering of lucerne under the two-cut strategy and white clover under the four-cut strategy. However, the 11- and 13 species mixtures presented a higher diversity of flowers during the flowering season. Interestingly, accumulated flower abundance was not significantly reduced under the two-cut strategy compared to no cut.
Pollinator profiles (visits by different functional groups of insects) were plant-species specific, i.e. at all sites, plant species attracted similar types of insects. Legume species mainly attracted large bees (honey bees and bumblebees), while herbs attracted other insect groups, in particular syrphids and other flies.
Our results suggest that multi-species grassland mixtures can be designed to support a higher diversity of pollinators without compromising herbage yield. In particular, adding forbs to the grass-legume mixtures and using a two-cut strategy rather than four cuts per year, may increase flower resources available for a larger range of wild pollinators
Differential Phase-contrast Interior Tomography
Differential phase contrast interior tomography allows for reconstruction of
a refractive index distribution over a region of interest (ROI) for
visualization and analysis of internal structures inside a large biological
specimen. In this imaging mode, x-ray beams target the ROI with a narrow beam
aperture, offering more imaging flexibility at less ionizing radiation.
Inspired by recently developed compressive sensing theory, in numerical
analysis framework, we prove that exact interior reconstruction can be achieved
on an ROI via the total variation minimization from truncated differential
projection data through the ROI, assuming a piecewise constant distribution of
the refractive index in the ROI. Then, we develop an iterative algorithm for
the interior reconstruction and perform numerical simulation experiments to
demonstrate the feasibility of our proposed approach
Soil nutrient levels define herbage yield but not root biomass in a multispecies grass-legume ley
The response of above- and below-ground biomass to soil nutrient availability is crucial for estimating belowground carbon input and predicting changes in soil carbon storage. However, the response is far from clear at plant community level, especially for grassland systems. Using a long-term field experiment initiated 123 years ago with varying soil nutrient levels (deficient, sub-optimal, optimal and over-optimal) established by use of two nutrient sources (animal manure or mineral fertiliser), we examined the effects of soil nutrient level and source on herbage yield and composition, root biomass and root-to-shoot (R/S) ratio of an unfertilised multispecies grass-legume ley. Increased nutrient levels enhanced herbage yield, but did not affect root biomass. The R/S ratio decreased from deficient to sub-optimal level, but remained constant from optimal to over-optimal level. Nutrient source did not influence herbage yield, root biomass or R/S ratio, but the legume proportion increased in soils previously receiving mineral fertiliser. The R/S ratio decreased with herbage yield, but did not vary with herbage composition. We conclude that soil nutrient level and herbage yield rather than nutrient source and herbage composition determine biomass allocation between aboveground and belowground in temperate grassland leys
Diet Shapes Mortality Response to Trauma in Old Tephritid Fruit Flies.
Despite the importance of trauma in healthspan and lifespan in humans as well as in non-human species, with one important exception the literature in both gerontology and ecology contains virtually no experimental demographic studies concerned with trauma in any species. We used dietary manipulation [full diet (F) versus sugar-only (S)] to produce four levels of frailty in 55-day old tephritid fruit flies (Anastrepha ludens) that were then subject to the trauma of cage transfer stress (n = 900/sex in each of the 4 treatments). The key results included the following: (1) there is a trauma effect caused by the transfer that depends on previous diet before transfer, new diet after transfer and gender of the fly; (2) males are more vulnerable than females; (3) if initial diet was F, flies are relatively immune against the trauma, and the subsequent diet (F or S) does not matter; (4) however if initial diet was S, then the effect of the trauma depends largely on the diet after the transfer; (5) flies transferred from S to F diets do very well in terms of remaining longevity (i.e. greatest remaining longevity), while flies transferred from S to S diet do poorly (i.e. shortest remaining longevity). We discuss both the strengths and weaknesses of this study and implications of the results
Diversity promotes production of ryegrass-clover leys through inclusion of competitive forb species
Highly productive temporary grasslands in Europe are usually composed of only a few plant species, and are typically dominated by perennial ryegrass-clover mixtures. Including additional competitive forb species holds potential for enhancing productivity in temporary grasslands, but requires further demonstration. In a grassland biodiversity experiment, one or all of the three forb species: chicory (Cichorium intybus L.), caraway (Carum carvi L.) and plantain (Plantago lanceolata L.), were grown in different proportions with the perennial ryegrass (Lolium perenne L.)-red clover (Trifolium pratense L.)mixture under two slurry application levels (0 and 250 kg total N ha-1 year-1). Dry matter (DM) yield and botanical composition were determined in 2014 and 2015. Results showed that plantain-containing mixtures significantly increased DM yield by on average 9.5% (20% plantain in seed mixture) to 13.6% (60% plantain) compared to the ryegrass-clover mixture, while other mixtures with forb species produced yields similar to that of the ryegrass-clover mixture. These effects were independent of slurry application and consistent over two years. Moreover, plantain-containing mixtures produced higher yield than
chicory- and caraway-containing mixtures, through greater biomass of plantain and/or complementary effects on red clover. These findings firstly demonstrate that increasing species diversity through including certain competitive forbs promotes production of ryegrass-clover mixtures
Physicochemical Properties and Catalytic Behavior of the Molecular Sieve SSZ-70
SSZ-70 is synthesized using 1,3-bis(isobutyl)imidazolium, 1,3-bis(cyclohexyl)imidazolium, and 1,3-bis(cycloheptyl)imidazolium structure directing agents (SDAs), and the solids obtained are characterized by powder X-ray diffraction (XRD), ^(29)Si magic angle spinning nuclear magnetic resonance (MAS NMR), electron microscopy, nitrogen and hydrocarbon adsorption, and thermogravimetric analyses. The physicochemical properties of SSZ-70 show that it is a new molecular sieve that has similarities to MWW-type materials. The catalytic behavior of SSZ-70 is evaluated through the use of the constraint index (CI) test. Distinct differences in the reactivity between Al-SSZ-70 and SSZ-25 (MWW) are observed and are the consequences of the structural differences between these two molecular sieves
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