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A slow-fast trait continuum at the whole community level in relation to land-use intensification
(2024)
AbstractOrganismal functional strategies form a continuum from slow- to fast-growing organisms, in response to common drivers such as resource availability and disturbance. However, whether there is synchronisation of these strategies at the entire community level is unclear. Here, we combine trait data for 2800 above- and belowground taxa from 14 trophic guilds spanning a disturbance and resource availability gradient in German grasslands. The results indicate that most guilds consistently respond to these drivers through both direct and trophically mediated effects, resulting in a ‘slow-fast’ axis at the level of the entire community. Using 15 indicators of carbon and nutrient fluxes, biomass production and decomposition, we also show that fast trait communities are associated with faster rates of ecosystem functioning. These findings demonstrate that ‘slow’ and ‘fast’ strategies can be manifested at the level of whole communities, opening new avenues of ecosystem-level functional classification.
Spray Phenomena and their Influence on the Ignition Performance of a Modern Aeroengine Combustor
(2008)
Computation is classically studied in terms of automata, formal languages and algorithms; yet, the relation between neural dynamics and symbolic representations and operations is still unclear in traditional eliminative connectionism. Therefore, we suggest a unique perspective on this central issue, to which we would like to refer as to transparent connectionism, by proposing accounts of how symbolic computation can be implemented in neural substrates. In this study we first introduce a new model of dynamics on a symbolic space, the versatile shift, showing that it supports the real-time simulation of a range of automata. We then show that the Gödelization of versatile shifts defines nonlinear dynamical automata, dynamical systems evolving on a vectorial space. Finally, we present a mapping between nonlinear dynamical automata and recurrent artificial neural networks. The mapping defines an architecture characterized by its granular modularity, where data, symbolic operations and their control are not only distinguishable in activation space, but also spatially localizable in the network itself, while maintaining a distributed encoding of symbolic representations. The resulting networks simulate automata in real-time and are programmed directly, in absence of network training. To discuss the unique characteristics of the architecture and their consequences, we present two examples: i) the design of a Central Pattern Generator from a finite-state locomotive controller, and ii) the creation of a network simulating a system of interactive automata that supports the parsing of garden-path sentences as investigated in psycholinguistics experiments.
Europe and the Middle East
(2018)
In 2017, the dominant greenhouse gases released into Earth’s
atmosphere—carbon dioxide, methane, and nitrous oxide—
reached new record highs. The annual global average carbon
dioxide concentration at Earth’s surface for 2017 was 405.0
± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in
the modern atmospheric measurement record and in ice core
records dating back as far as 800 000 years. The global growth
rate of CO2 has nearly quadrupled since the early 1960s.
With ENSO-neutral conditions present in the central and
eastern equatorial Pacific Ocean during most of the year and
weak La Niña conditions notable at the start and end, the global
temperature across land and ocean surfaces ranked as the second or third highest, depending on the dataset, since records
began in the mid-to-late 1800s. Notably, it was the warmest
non-El Niño year in the instrumental record. Above Earth’s
surface, the annual lower tropospheric temperature was also
either second or third highest according to all datasets analyzed. The lower stratospheric temperature was about 0.2°C
higher than the record cold temperature of 2016 according to
most of the in situ and satellite datasets.
Several countries, including Argentina, Uruguay, Spain, and
Bulgaria, reported record high annual temperatures. Mexico
broke its annual record for the fourth consecutive year. On 27
January, the temperature reached 43.4°C at Puerto Madryn,
Argentina—the highest temperature recorded so far south
(43°S) anywhere in the world. On 28 May in Turbat, western
Pakistan, the high of 53.5°C tied Pakistan’s all-time highest
temperature and became the world-record highest temperature for May.
In the Arctic, the 2017 land surface temperature was 1.6°C
above the 1981–2010 average, the second highest since the
record began in 1900, behind only 2016. The five highest annual
Arctic temperatures have all occurred since 2007. Exceptionally
high temperatures were observed in the permafrost across
the Arctic, with record values reported in much of Alaska and
northwestern Canada. In August, high sea surface temperature
(SST) records were broken for the Chukchi Sea, with some
regions as warm as +11°C, or 3° to 4°C warmer than the longterm mean (1982–present). According to paleoclimate studies,
today’s abnormally warm Arctic air and SSTs have not been
observed in the last 2000 years. The increasing temperatures
have led to decreasing Arctic sea ice extent and thickness. On
7 March, sea ice extent at the end of the growth season saw
its lowest maximum in the 37-year satellite record, covering
8% less area than the 1981–2010 average. The Arctic sea ice
minimum on 13 September was the eighth lowest on record
and covered 25% less area than the long-term mean.
Preliminary data indicate that glaciers across the world lost
mass for the 38th consecutive year on record; the declines
are remarkably consistent from region to region. Cumulatively
since 1980, this loss is equivalent to slicing 22 meters off the
top of the average glacier.
Antarctic sea ice extent remained below average for all of
2017, with record lows during the first four months. Over
the continent, the austral summer seasonal melt extent and
melt index were the second highest since 2005, mostly due to
strong positive anomalies of air temperature over most of the
West Antarctic coast. In contrast, the East Antarctic Plateau
saw record low mean temperatures in March. The year was
also distinguished by the second smallest Antarctic ozone hole
observed since 1988.
Across the global oceans, the overall long-term SST warming
trend remained strong. Although SST cooled slightly from 2016
to 2017, the last three years produced the three highest annual
values observed; these high anomalies have been associated
with widespread coral bleaching. The most recent global coral
bleaching lasted three full years, June 2014 to May 2017, and
was the longest, most widespread, and almost certainly most
destructive such event on record. Global integrals of 0–700-
m and 0–2000-m ocean heat content reached record highs in
2017, and global mean sea level during the year became the
highest annual average in the 25-year satellite altimetry record,
rising to 77 mm above the 1993 average.
In the tropics, 2017 saw 85 named tropical storms, slightly
above the 1981–2010 average of 82. The North Atlantic basin
was the only basin that featured an above-normal season, its
seventh most active in the 164-year record. Three hurricanes
in the basin were especially notable. Harvey produced record
rainfall totals in areas of Texas and Louisiana, including a storm
total of 1538.7 mm near Beaumont, Texas, which far exceeds
the previous known U.S. tropical cyclone record of 1320.8 mm.
Irma was the strongest tropical cyclone globally in 2017 and the
strongest Atlantic hurricane outside of the Gulf of Mexico and
Caribbean on record with maximum winds of 295 km h−1. Maria
caused catastrophic destruction across the Caribbean Islands,
including devastating wind damage and flooding across Puerto
Rico. Elsewhere, the western North Pacific, South Indian, and
Australian basins were all particularly quiet.
Precipitation over global land areas in 2017 was clearly above
the long-term average. Among noteworthy regional precipitation records in 2017, Russia reported its second wettest year
on record (after 2013) and Norway experienced its sixth wettest year since records began in 1900. Across India, heavy rain
and flood-related incidents during the monsoon season claimed
around 800 lives. In August and September, above-normal
precipitation triggered the most devastating floods in more
than a decade in the Venezuelan states of Bolívar and Delta
Amacuro. In Nigeria, heavy rain during August and September
caused the Niger and Benue Rivers to overflow, bringing floods
that displaced more than 100 000 people.
Global fire activity was the lowest since at least 2003; however, high activity occurred in parts of North America, South
America, and Europe, with an unusually long season in Spain
and Portugal, which had their second and third driest years
on record, respectively. Devastating fires impacted British
Columbia, destroying 1.2 million hectares of timber, bush, and
grassland, due in part to the region’s driest summer on record.
In the United States, an extreme western wildfire season
burned over 4 million hectares; the total costs of $18 billion
tripled the previous U.S. annual wildfire cost record set in 1991.
The adoption of graphene in electronics, optoelectronics, and photonics is hindered by the difficulty in obtaining high‐quality material on technologically relevant substrates, over wafer‐scale sizes, and with metal contamination levels compatible with industrial requirements. To date, the direct growth of graphene on insulating substrates has proved to be challenging, usually requiring metal‐catalysts or yielding defective graphene. In this work, a metal‐free approach implemented in commercially available reactors to obtain high‐quality monolayer graphene on c‐plane sapphire substrates via chemical vapor deposition is demonstrated. Low energy electron diffraction, low energy electron microscopy, and scanning tunneling microscopy measurements identify the Al‐rich reconstruction of sapphire to be crucial for obtaining epitaxial graphene. Raman spectroscopy and electrical transport measurements reveal high‐quality graphene with mobilities consistently above 2000 cm2 V−1 s−1. The process is scaled up to 4 and 6 in. wafers sizes and metal contamination levels are retrieved to be within the limits for back‐end‐of‐line integration. The growth process introduced here establishes a method for the synthesis of wafer‐scale graphene films on a technologically viable basis.
Analysemethoden
(2022)
Die Geoarchäologie verfügt über ein äußerst breites und stetig wachsendes Spektrum an Analysemethoden, die sowohl im Labor als auch im Gelände angewandt werden. Das Kapitel stellt alle gebräuchlichen Methoden vor und soll insbesondere Nachwuchswissenschaftlern als Werkzeugkasten dienen. Zunächst liegt der Fokus auf den bodenkundlich-geomorphologischen Standardmethoden, wie Korngrößenanalyse (Bodenart), Bodenfarbe, Gehalt an organischer Substanz, Carbonatgehalt, Bodenreaktion (pH) und vielfältigen Multielement-Analysen zur Lösung verschiedener Fragestellungen. Für die Paläoumweltforschung haben die Pollenanalyse sowie die Analyse von Nichtpollen-Palynomorphen (NPP) schon seit vielen Jahrzehnten eine große Bedeutung. Für größere biogene Reste stehen die Makrorestanalyse und die Anthrakologie zur Untersuchung von Holzkohlen zur Verfügung. Weiterhin beschreibt das Kapitel die Methode der Mikromorphologie (Dünnschliffe), die Analyse von Biomarkern und stabilen Isotopen sowie die Bestimmung und Einordnung von Foraminiferen und Ostrakoden aus aquatischen Ökosystemen. Beschrieben werden außerdem Ansätze zu Phytolithen und Messungen mithilfe der Fourier-Tranformations-Infrarotspektrometrie (FTIR).