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We investigate the action of the Atkin operator on spaces of overconvergent p-adic modular forms. Our contributions are both computational and geometric. We present several algorithms to compute the spectrum of the Atkin operator, as well as its p-adic variation as a function of the weight. As an application, we explicitly construct Heegner-type points on elliptic curves. We then make a geometric study of the Atkin operator, and prove a potential semi-stability theorem for correspondences. We explicitly determine the stable models of various Hecke operators on quaternionic Shimura curves, and make a purely geometric study of canonical subgroups.

Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial–interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils., Atmospheric CO2 increases during the last deglaciation have been linked to the destabilisation of permafrost carbon reservoirs. Here, using a sediment core from the Laptev Sea, Tesi et al. indicate a massive supply of permafrost carbon was released from Siberia following active layer deepening.

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We applied species sensitivity distributions (SSDs), commonly used in chemical risk assessment, to quantify the impact of water‐flow velocity on the presence of fish species in a river. SSDs for water‐flow velocity were derived from observational field data (maximal velocity at which species occur, Vmax) and laboratory measurements (critical swimming velocity, Vcrit). By calculating the potentially affected fraction of the fish species of the river Rhine, effects of water‐flow velocity on different life stages and guilds were estimated. Vmax values for adults were significantly higher than those for juveniles and larvae. At water‐flow velocity of 60 cm s−1, half of the adults were affected, while half of the non‐adult life stages were affected at velocities of 25 to 29 cm s−1. There was a positive correlation between body size and fish tolerance to water‐flow. As expected, rheophilic species tolerated higher water‐flow velocities than eurytopic and limnophilic species. Maximal velocities measured in littoral zones of the Rhine were, on average, 10 cm s−1, corresponding to an affected fraction of 2%. An increase in water‐flow velocity up to 120 cm s−1 as a result of passing vessels caused an increase in affected species to 75%. For a successful ecological river management, the SSD method can be used to quantify the trait‐mediated effects of water‐flow alterations on occurring species enabling to compare and rank the effects of chemical and physical stress.

Contains fulltext : 164809pre.pdf (Author’s version preprint ) (Open Access) In this chapter, we describe a number of the citizen science projects RIVM took part in. The Smart Emission project in Nijmegen is one of the pilot projects. In this book chapter, we give examples of the lessons learned and the experiences gained. We provide a brief description of the planned innovations of the environmental monitoring, and how these innovations will help to ensure the continuity and effectiveness of citizen science measurements. The initial focus will be on air quality, but we expect that application is possible with other environmental parameters such as noise and water quality, light, vibration, radiation and meteorological parameters. These applications will follow in a later phase of the program. The final goal is to have a hybrid, flexible (air quality) network using different types of sensors, consisting of reference instruments, sensors of intermediate cost and quality, low cost sensors, and satellite observations. The data of this network may be provided by different parties, including citizens groups, cities, NGOs and official measurement institutes. In short, our ambition is to make citizen science data an integral part of standard procedures and models for determining air quality. Book after the First European Citizen Science Conference, Berlin, 19-21 May 2016

CT3 ; EnjS4; International audience; As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wild␣re, and hydrologic carbon ␣ux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identi␣ed water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous ␣ndings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced.

Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding habits could have a major impact on soil food web functioning. Here, we investigate the effects of gender and developmental stage on the nematode body sizes in coarse and loamy soils. Besides Neodiplogasteridae, our predators are much larger than other soil-dwelling nematodes from their early developmental stage onwards. From juvenile to adult, the predatory Aporcelaimellus (Kruskal–Wallis P < 0.001), Dorylaimoides, and Tripyla (both P < 0.01) show great length increases during their developmental growth, in contrast to their possible prey (almost all P < 0.001). Less than 4% of the prey exceeds the length of the predatory adults, but more than 30% of the prey exceeds the length of the predatory juveniles. Potential body size ratios and some physical problems experienced by small fluid feeders attacking large prey are discussed in an attempt to summarize different prey-searching mechanisms and aggregative predatory responses in the soil system.

Background: Inhaled corticosteroids (ICSs) and long-acting β2-agonists (LABAs) are used to treat moderate to severe chronic obstructive pulmonary disease (COPD). Objective: To determine whether long-term ICS therapy, with and without LABAs, reduces inflammation and improves pulmonary function in COPD. Design: Randomized, placebo-controlled trial. (ClinicalTrials.gov registration number: NCT00158847) Setting: 2 university medical centers in The Netherlands. Patients: 114 steroid-naive current or former smokers with moderate to severe COPD. Measurements: Cell counts in bronchial biopsies and sputum (primary outcome); methacholine responsiveness at baseline, 6, and 30 months; and clinical outcomes every 3 months. Intervention: Random assignment by minimization method to receive fluticasone propionate, 500 μg twice daily, for 6 months (n = 31) or 30 months (n = 26); fluticasone, 500 μg twice daily, and salmeterol, 50 μg twice daily, for 30 months (single inhaler; n = 28); or placebo twice daily (n = 29). Results: 101 patients were greater than 70% adherent to therapy. Fluticasone therapy decreased counts of mucosal CD3+ cells (-55% [95% CI, -74% to -22%]; P - 0.004), CD4- cells (-78% [CI, -88% to 60%]; P < 0.001), CD8+ cells (-57% [CI, -77% to -18%]; P = 0.010), and mast cells (-38% [CI, -60% to -2%]; P = 0.039) and reduced hyperresponsiveness (P = 0.036) versus placebo at 6 months, with effects maintained after 30 months. Fluticasone therapy for 30 months reduced mast cell count and increased eosinophil count and percentage of intact epithelium, with accompanying reductions in sputum neutrophil, macrophage, and lymphocyte counts and improvements in FEV1 decline, dyspnea, and quality of life. Reductions in inflammatory cells correlated with clinical improvements. Discontinuing fluticasone therapy at 6 months increased counts of CD3+ cells (120% [CI, 24% to 289%]; P = 0.007), mast cells (218% [CI, 99% to 407%]; P < 0.001), and plasma cells (118% [CI, 9% to 336%]; P = 0.028) and worsened clinical outcome. Adding salmeterol improved FEV1 level. Limitations: The study was not designed to evaluate clinical outcomes. Measurement of primary outcome was not available for 24% of patients at 30 months. Conclusion: ICS therapy decreases inflammation and can attenuate decline in lung function in steroid-naive patients with moderate to severe COPD. Adding LABAs does not enhance these effects. Primary Funding Source: Netherlands Organization for Scientific Research, Netherlands Asthma Foundation, GlaxoSmithKline of The Netherlands, University Medical Center Groningen, and Leiden University Medical Center.

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Landbouwkundige activiteiten zijn een belangrijke bron van ammoniak (NH3), stikstofoxiden (NO), lachgas (N2O), methaan (CH4) en fijn stof (PM10 en PM2,5) in Nederland. De emissies voor de periode 1990-2013 zijn berekend met het National Emission Model for Agriculture (NEMA) met toepassing van nieuwe wetenschappelijke inzichten rond emissiefactoren voor ammoniak uitstallen en op basis van de nieuwe 2006 IPCC Guidelines. De rekenmethodiek gaat bij de berekening van de ammoniakemissie uit van de hoeveelheid totaal ammoniakaal stikstof (TAN) in de mest. De ammoniakemissie uit dierlijke mest, kunstmest en overige bronnen bedroeg in 2013 120 miljoen kg NH3, 1,5 miljoen kg minder dan in 2012, voornamelijk door meer emissiearmehuisvesting bij varkens en pluimvee. De N2O-emissie bedroeg zowel in 2012 als in 2013 ruim 19 miljoen kg. De NO-emissie nam licht toe van 16,7 naar 16,9 miljoen kg. De methaanemissie nam toe van 487 tot 499 miljoen kg. De emissie van fijn stof nam licht toe van 6,4 miljoen kg PM10 in 2012 tot 6,5 miljoen kg in 2013 door een toename van het aantal leghennen. De emissie van PM2,5 bedroeg in beide jaren 0,6 miljoen kg. Sinds 1990 is de ammoniakemissie uit dierlijke mest en kunstmest met bijna 70% gedaald, vooral door een lagere stikstof-uitscheiding door landbouwhuisdieren en emissiearme mesttoedieningstechnieken.Lachgas en stikstofoxiden daalden in dezelfde periode eveneens, maar minder scherp (ca. 40%) vanwege hogere emissies door het ondergronds aanwenden van mest (N2O) en door de omschakeling van stalsystemen met dunne naar vastemest bij pluimvee (N2O en NO). Tussen 1990 en 2013 daalde de emissie van methaan met 17%, wat vrijwel geheel verklaard kan worden door een afname in de dieraantallen.

The Arctic is a water-rich region, with freshwater systems covering 16 % of the northern permafrost landscape. The thawing of this permafrost creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic and lotic systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas, vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying variables determine the degree to which permafrost thaw manifests as thermokarst, whether thermokarst leads to slumping or the formation of thermokarst lakes, and the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying variables determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted systems is also likely to change, with thaw-impacted lakes and streams having unique microbiological communities, and showing differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO2 and CH4), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to address the key gaps in understanding in order to predict the full effects of permafrost thaw on aquatic ecosystems throughout the Arctic, and their consequential feedbacks to climate.

As Arctic regions warm and frozen soils thaw, the large organic carbon pool stored in permafrost becomes increasingly vulnerable to decomposition or transport. The transfer of newly mobilized carbon to the atmosphere and its potential influence upon climate change will largely depend on the degradability of carbon delivered to aquatic ecosystems. Dissolved organic carbon (DOC) is a key regulator of aquatic metabolism, yet knowledge of the mechanistic controls on DOC biodegradability is currently poor due to a scarcity of long-term data sets, limited spatial coverage of available data, and methodological diversity. Here, we performed parallel biodegradable DOC (BDOC) experiments at six Arctic sites (16 experiments) using a standardized incubation protocol to examine the effect of methodological differences commonly used in the literature. We also synthesized results from 14 aquatic and soil leachate BDOC studies from across the circum-arctic permafrost region to examine pan-arctic trends in BDOC. An increasing extent of permafrost across the landscape resulted in higher DOC losses in both soil and aquatic systems. We hypothesize that the unique composition of (yedoma) permafrost-derived DOC combined with limited prior microbial processing due to low soil temperature and relatively short flow path lengths and transport times, contributed to a higher overall terrestrial and freshwater DOC loss. Additionally, we found that the fraction of BDOC decreased moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly biodegradable DOC is lost in headwater streams. We also observed a seasonal (January–December) decrease in BDOC in large streams and rivers, but saw no apparent change in smaller streams or soil leachates. We attribute this seasonal change to a combination of factors including shifts in carbon source, changing DOC residence time related to increasing thaw-depth, increasing water temperatures later in the summer, as well as decreasing hydrologic connectivity between soils and surface water as the thaw season progresses. Our results suggest that future climate warming-induced shifts of continuous permafrost into discontinuous permafrost regions could affect the degradation potential of thaw-released DOC, the amount of BDOC, as well as its variability throughout the Arctic summer. We lastly recommend a standardized BDOC protocol to facilitate the comparison of future work and improve our knowledge of processing and transport of DOC in a changing Arctic.

To assess the impact of atmospheric aerosols on health, climate, and air traffic, aerosol properties must be measured with fine spatial and temporal sampling. This can be achieved by actively involving citizens and the technology they own to form an atmospheric measurement network. We establish this new measurement strategy by developing and deploying iSPEX, a low-cost, mass-producible optical add-on for smartphones with a corresponding app. The aerosol optical thickness (AOT) maps derived from iSPEX spectropolarimetric measurements of the daytime cloud-free sky by thousands of citizen scientists throughout the Netherlands are in good agreement with the spatial AOT structure derived from satellite imagery and temporal AOT variations derived from ground-based precision photometry. These maps show structures at scales of kilometers that are typical for urban air pollution, indicating the potential of iSPEX to provide information about aerosol properties at locations and at times that are not covered by current monitoring efforts. Key Points The iSPEX add-on turns smartphones into aerosol measurement devicesThousands of iSPEX measurements across the Netherlands form AOT mapsThe iSPEX AOT data match MODIS and AERONET data and have 2 km resolution

Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remain uncertain. Here we find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.

The distance–decay relationship has been claimed to be a predictor for biological diversity because it unites several ecological phenomena such as dispersal ability and environmental structure. The effect of long-term disturbances on distance decay, however, has been widely overlooked, especially for microorganisms. We examine the effect of eutrophication on the distance–decay relationship in communities of attached diatoms in three peatland areas: mesotrophic, eutrophic and hypertrophic. The study follows a spatially explicit sampling scheme, collecting evenly spaced samples along 6-km sampling tracks. The three areas shared 24% of the total number of species, but the different nutrient levels in the three areas are reflected by the prominence of low profile and planktonic diatom species. Our study demonstrates that eutrophication can affect distance–decay relationships by decreasing turnover rates in microorganisms. Diatom communities are shown to be constrained by both environmental and spatial features, whose relative importance depends on the degree of eutrophication. Under eutrophic conditions, species are filtered from the regional species pool and community structure responds strongly to environmental factors (water chemistry variables and depth), while in mesotrophic environments, purely spatial processes play a prominent role in structuring diatom communities. These findings reveal that homogenisation of communities triggered by environmental disturbance is an ecological phenomenon of importance in the microbial world.

Landbouwkundige activiteiten zijn een belangrijke bron van ammoniak (NH3), stikstofoxide (NO), lachgas (N2O), methaan (CH4) en fijn stof in Nederland. De emissies voor de periode 1990-2012 zijn berekend met NEMA. In 2013 is NEMA uitgebreid met modules voor N2O, NO, CH4 en fijn stof. De rekenmethodiek gaat bij de berekening van de ammoniakemissie uit van de hoeveelheid totaal ammoniakaal stikstof (TAN) in de mest. De ammoniakemissie uit dierlijke mest en kunstmest bedroeg in 2012 ruim 108 miljoen kg NH3, 5 miljoen kg minder dan in 2011, voornamelijk door een lagere stikstofuitscheiding in dierlijke mest en een toename van de mestexport. In lijn hiermee nam de N2O-emissie af van 22,4 tot 21,7 miljoen kg. De NO-emissie nam af van 19,9 naar 19,1 miljoen kg. Sinds 1990 is de ammoniakemissie uit dierlijke mest en kunstmest met bijna 70% gedaald, vooral door een lagere stikstofuitscheiding door landbouwhuisdieren en emissiearme toedieningstechnieken. Lachgas en stikstofoxiden daalden in dezelfde periode eveneens, maar minder scherp (ca. 40%) vanwege hogere emissies door ondergronds aanwenden van mest (N2O) en door de omschakeling van stalsystemen met dunne naar droge mest bij pluimvee (N2O en NO). De totale emissie van methaan veranderde tussen 2011 en 2012 nauwelijks, en komt uit op 437,3 miljoen kg. Tussen 1990 en 2012 daalde de emissie met 14%, wat vrijwel geheel verklaard kan worden door een afname in de dieraantallen. Fijn stof ten slotte, daalde van 6,6 naar 6,4 miljoen kg PM10 als gevolg van het toenemende aandeel stallen met luchtwasser. Hiervan is 0,6 miljoen kg PM2,5.