Power, competition, and the nature of history

AbstractHistorians have debated whether pathways and events from the past to the present are influenced largely by contingency, the dependence of outcomes on particular prior conditions, or whether there is long-term emergent directional change. Previous arguments for predictability in evolutionary history relied on the high frequency of convergence, but the repeated evolution of widely favored adaptations need not imply long-term directionality. Using evidence from the fossil record and arguments concerning the metabolic evolution of organisms, I show here that power (total energy taken up and expended per unit time) has increased stepwise over time at ecosystem-level and global scales thanks to the ratchet-like, cumulative effects of competition and cooperation and to the disproportionate influence of powerful top competitors and opportunistic species on emergent ecosystem properties and processes. The history of life therefore exhibits emergent directionality at large ecosystem-wide scales toward greater power

Effect of slatted and solid floors and permeability of floors in pig houses on environment, animal welfare and health and food safety: a review of literature

An integrated approach can improve understanding of floor performance. Not only gap width or percentage of slatted floor is important, but a minimum percentage of permeability of the total floor area appears to be decisiv

Regional variations in tropical high intertidal gastropod assemblages

High intertidal gastropod assemblages in the Inda-Malaysian area and western Indian Ocean have a higher incidence of presumed antipredatory devices (obstructed apertures, inflexible opercula, low spires, and strong external shell sculpture) than high intertidal gastropods found elsewhere in the tropics...

Effect van volledig roostervloer en dichte vloer en doorlaatbaarheid van vloeren in varkensstallen op milieu, diergezondheid en -welzijn en voedselveiligheid: een literatuur review

Een integrale benadering kan leiden tot het verbeteren van een vloeruitvoering. Niet alleen spleetbreedte of aandeel roostervloer is belangrijk, maar een minimum percentage doorlaatbaarheid van het totale vloeroppervlak is doorslaggeven

Arbeidsproductiviteit op vleeskuikenbedrijven = Labour productivity on broiler farms

Productivity of labour on broiler farms is expressed as kg live weight per labour our and is especially influenced by farm size. The average productivity of labour amount to 492 kg per ou

Quality and standardization in blood component preparation with an automated blood processing technique

The use of automated blood processors in combination with bottom and top blood containers has been found to improve the standardization and quality of blood components. A study was performed to validate a new type of processor (Optipress® II) and compare its performance with a first generation processor (Optipress® I). Primary separation on the Optipress II was investigated on 570mL (± 10%) of anticoagulated blood in a nonpaired study. In addition, the quality of the products in routine production was compared between the results of the Optipress I and Optipress II. The whole blood units were kept overnight at room temperature (20 ± 2°C). Separation was performed under conditions to obtain 55mL buffy coats with a 50% haematocrit (ht). Platelet concentrate preparation was investigated in a paired study and compared to the routine manual method using PAS II additive solution. Parameters studied were volume, red cell, white cell and platelet counts, ht, haemoglobin (hb, total and free). Primary separation was more efficient in the Optipress II because the platelet count was lower in the erythrocyte concentrates (P<0.0001), platelets were lower in plasma (P<0.0001) and platelet counts were higher in buffy coats (P<0.0001). Buffy coat volume showed less variation (Optipress II VC=4%, Optipress I VC= 7.4%). Secondary separation did not show differences between the Optipress II and manual method but was advantageous because of the automatic termination of the procedure. Further improvement of standardization in blood component preparation is possible with an automated blood processor, leading to improvement of the quality of blood products for patient care

A quasi-2D integrated experimental–numerical approach to high-fidelity mechanical analysis of metallic microstructures

Integrated experimental–numerical testing on bulk metal alloys with fine, complex microstructures is known to be highly challenging, since measurements are restricted to the sample surface, thereby failing to capture the effects of the 3D subsurface microstructure. Consequently, a quantitative comparison of deformation fields between experiments and simulations is hardly possible. To overcome this, we propose a novel ‘quasi-2D’ integrated experimental–numerical testing methodology that hinges on the fabrication of μm-thin specimens with practically through-thickness microstructures over large regions of &gt;100 μm. The specimens are fully characterized from both surfaces and tested in-situ to retrieve microstructure-resolved deformation fields. Simultaneously, the full microstructure is discretized in 3D and simulated. This allows for a detailed, one-to-one quantitative comparison of deformation fields between experiments and simulations, with negligible uncertainty in the subsurface microstructure. Consequently, a degree of agreement between experiments and simulations is attained which we believe to be unprecedented at this scale. We demonstrate the capabilities of the framework on polycrystalline ferritic steel and dual-phase ferritic–martensitic steel specimens. At the mesoscale, the methodology enables quantitative comparisons of the interaction between multiple grains, while, at the microscale, it enables advancement of numerical models by direct confrontation with detailed experimental observations. Specifically, it is revealed that the individual slip system activity maps, identified with SSLIP, near a grain boundary can only be reasonably predicted by enhancing the adopted crystal plasticity simulations with a discrete slip plane model. Additionally, the experimentally observed strong anisotropic plasticity of martensite can only be captured with a substructure-enriched crystal plasticity model.</p

Nocturnal dissolved organic matter release by turf algae and its role in the microbialization of reefs

The increased release of dissolved organic matter (DOM) by algae has been associated with the fast but inefficient growth of opportunistic microbial pathogens and the ongoing degradation of coral reefs. Turf algae (consortia of microalgae and macroalgae commonly including cyanobacteria) dominate benthic communities on many reefs worldwide. Opposite to other reef algae that predominantly release DOM during the day, turf algae containing cyanobacteria may additionally release large amounts of DOM at night. However, this night-DOM release and its potential contribution to the microbialization of reefs remains to be investigated. We first tested the occurrence of hypoxic conditions at the turf algae-water interface, as a lack of oxygen will facilitate the production and release of fermentation intermediates as night-time DOM. Second, the dissolved organic carbon (DOC) release by turf algae was quantified during day time and nighttime, and the quality of day and night exudates as food for bacterioplankton was tested. Finally, DOC release rates of turf algae were combined with estimates of DOC release based on benthic community composition in 1973 and 2013 to explore how changes in benthic community composition affected the contribution of night-DOC to the reef-wide DOC production. A rapid shift from supersaturated to hypoxic conditions at the turf algae-water interface occurred immediately after the onset of darkness, resulting in night-DOC release rates similar to those during daytime. Bioassays revealed major differences in the quality between day and night exudates: Night-DOC was utilized by bacterioplankton two times faster than day-DOC, but yielded a four times lower growth efficiency. Changes in benthic community composition were estimated to have resulted in a doubling of DOC release since 1973, due to an increasing abundance of benthic cyanobacterial mats (BCMs), with night-DOC release by BCMs and turf algae accounting for >50% of the total release over a diurnal cycle. Night-DOC released by BCMs and turf algae is likely an important driver in the microbialization of reefs by stimulating microbial respiration at the expense of energy and nutrient transfer to higher trophic levels via the microbial loop, thereby threatening the productivity and biodiversity of these unique ecosystems. Read the free Plain Language Summary for this article on the Journal blog

Stofreductie in kuikenstal dankzij oliefilm

Stof in de stal is al jarenlang een aandachtspunt uit oogpunt van arbo en diergezondheid. De laatste jaren is daar de emissie van fijnstof naar de buitenlucht bijgekomen, aangezien de EU normen heeft gesteld voor maximale concentraties fijnstof in de buitenlucht. Er zijn normen gesteld voor deeltjes kleiner dan 10 micrometer (PM10) en voor deeltjes kleiner dan 2,5 micrometer (PM2.5). De veehouderij draagt naast verkeer en industrie bij aan de emissie van fijnstof. Het merendeel van het fijnstof uit de veehouderij komt uit pluimvee- en varkensstalle