We performed an ensemble of twelve five‐year experiments using a coupled climate‐carbon‐cycle model with scenarios of prescribed atmospheric carbon dioxide concentration; CO2 was instantaneously ...doubled or quadrupled at the start of the experiments. Within these five years, climate feedback is not significantly influenced by the effects of climate change on the carbon system. However, rapid changes take place, within much less than a year, due to the physiological effect of CO2 on plant stomatal conductance, leading to adjustment in the shortwave cloud radiative effect over land, due to a reduction in low cloud cover. This causes a 10% enhancement to the radiative forcing due to CO2, which leads to an increase in the equilibrium warming of 0.4 and 0.7 K for doubling and quadrupling. The implications for calibration of energy‐balance models are discussed.
A simple and effective stepwise-method has been developed to remove defects from the top graphene layers of highly orientated pyrolytic graphite. Using a combination of ozone exposure and moderately ...high temperature we have shown that a defect-rich graphite surface can be modified to generate a graphene-like surface containing a negligible amount of oxygen, hydrogen and
sp
3 carbon. We report definitive X-ray photoelectron and X-ray absorption spectroscopy analysis after each stage of the process, suggest a mechanism by which the modification occurs and propose it as a route towards the preparation or manipulation of pristine graphene samples.
ABSTRACT We report the detection of a 78.1 0.5 day period in the X-ray light curve of the extreme ultraluminous X-ray source NGC 5907 ULX1 ( L X,peak ∼ 5 × 10 40 erg s−1), discovered during an ...extensive monitoring program with Swift. These periodic variations are strong, with the observed flux changing by a factor of ∼3-4 between the peaks and the troughs of the cycle; our simulations suggest that the observed periodicity is detected comfortably in excess of 3 significance. We discuss possible origins for this X-ray period, but conclude that at the current time we cannot robustly distinguish between orbital and super-orbital variations.
Objective: The objective of the study was to assess whether weekly administration of 40 mg pegvisomant (PEG-V) improves quality of life (QoL) and metabolic parameters in acromegalic patients with ...normal age-adjusted IGF-I concentrations during long-acting somatostatin analog (SSA) treatment.
Design: This was a prospective, investigator-initiated, double blind, placebo-controlled, crossover study. Twenty acromegalic subjects received either PEG-V or placebo for two consecutive treatment periods of 16 wk, separated by a washout period of 4 wk. Efficacy was assessed as change between baseline and end of each treatment period. QoL was assessed by the Acromegaly Quality of Life Questionnaire (AcroQoL) and the Patient-Assessed Acromegaly Symptom Questionnaire (PASQ).
Results: The AcroQoL (P = 0.008) and AcroQoL physical (P = 0.002) improved significantly after PEG-V was added. The addition of PEG-V also significantly improved the PASQ (P = 0.038) and the single PASQ questions, perspiration (P = 0.024), soft tissue swelling (P = 0.036), and overall health status (P = 0.035). No significant change in Z-score of IGF-I (P = 0.34) was observed during addition of PEG-V. Transient liver enzyme elevations were observed in five subjects (25%).
Conclusion: Improvement in quality of life was observed without significant change in IGF-I after the addition of 40 mg pegvisomant weekly to monthly SSA therapy in acromegalic patients who had normalized IGF-I on SSA monotherapy. These data question the current recommendations in how to assess disease activity in acromegaly. Moreover, the findings question the validity of the current approach of medical treatment in which pegvisomant is used only when SSA therapy has failed to normalize IGF-I.
Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the northwest of the European Union (Ireland, United Kingdom, Denmark, the Netherlands, ...Belgium, Northern France and Germany). The main sources of data were national reports for the third reporting period for the NiD (2004–2007) and results of the MITERRA-EUROPE model. Implementation of the NiD in the considered member states is fairly comparable regarding restrictions for where and when to apply fertilizer and manure, but very different regarding application limits for N fertilization. Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995 is a major contribution to the decrease of the soil N balance (N surplus), particularly in Belgium, Denmark, Ireland, the Netherlands and the United Kingdom. This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries. This decrease is less prominent for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of the Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater and tenacious exceedance of the water quality standards. On average the gross N balance in 2008 for the seven member states in EUROSTAT and in national reports was about 20 kg N ha−1 yr−1 lower than by MITERRA. The major cause is higher estimates of N removal in national reports which can amount to more than 50 kg N ha−1 yr−1. Differences between procedures in member states to assess nitrogen balances and water quality and a lack of cross-boundary policy evaluations are handicaps when benchmarking the effectiveness of the NiD. This provides a challenge for the European Commission and its member states, as the NiD remains an important piece of legislation for protecting drinking water quality in regions with many private or small public production facilities and controlling aquatic eutrophication from agricultural sources.
Windows of opportunity Balke, Thorsten; Bouma, Tjeerd J.; Horstman, Erik M. ...
Marine ecology. Progress series (Halstenbek),
10/2011, Letnik:
440
Journal Article
Recenzirano
Odprti dostop
Physical processes limiting colonization of bare tidal flats by pioneer mangrove species have commonly been described but not yet quantified. Understanding thresholds to early seedling establishment ...is critical for successful restoration and management of mangrove forests. We determined how seedling establishment ofAvicennia albaBl. is affected by the combination of increasing hydrodynamic forces and sediment dynamics. As the buoyant propagules ofA. albaare dispersed by water, early establishment on bare tidal flats requires propagules to quickly anchor to stay in place. Flume studies and field observations showed that 3 thresholds have to be passed until the seedling is successfully established: (1) stranded propagules need an inundation- free period to rapidly develop roots that are long enough to withstand displacement by flooding, (2) roots need to become long enough to withstand seedling dislodgement by hydrodynamic forces from waves and currents, with the required root length being proportional to the force that needs to be resisted, (3) even longer roots are needed to survive high energy events that cause sheet erosion and can thereby induce seedling dislodgement. This sequence of thresholds implies that establishment of the pioneer mangrove speciesA. albarequires a suitable window of opportunity to pass all thresholds and underlines the importance of rapid root expansion as a crucial pioneer trait for the species.
•Biological amendments include biostimulants, organic amendments and inoculants.•Some biological amendments may have potential cumulative effects.•Modes of action of biological amendments in the ...field are not always understood.•Scientific evidence of field-scale benefits of biological amendments is limited.•On-farm participatory research has potential to provide valuable knowledge.
There is increasing interest in use of ‘alternative’ soil amendments in agriculture, but the wide range of resources and products available differ greatly in their potential to overcome soil constraints and improve nutrient use efficiency. The three main types of biological amendments can be categorised as biostimulants, organic amendments and microbial inoculants. Many have potential to influence biological, chemical and physical conditions of soil, but most are not well researched or easily used in agriculture. The main exception is legume inoculants, which are very well researched and contribute enormously to agricultural productivity when legumes are incorporated into farming systems. Biostimulants include amino acids, chitosan, seaweed extracts and humic substances. Organic amendments include manures, composts, compost derivatives and biochars. Microbial inoculants include specific bacterial inoculants for legumes, and less specialised rhizosphere bacteria, arbuscular mycorrhizal fungi, ectomycorrhizal fungi and a range of disease suppressing microorganisms. Some biological amendments applied to soil may be more effective when used in combinations rather than singly. Furthermore, those used over longer periods may have potential for cumulative effects not captured when used over shorter timeframes. Such differences in effectiveness would occur primarily where benefits involve microbial interactions with chemical and physical soil processes leading to slow transformations within the soil matrix that influence soil fertility and soil health. Similarly, addition of manures and composts may require several years for any quantifiable increase in soil organic C. Although considerable knowledge of the modes of action of many biological amendments is available, their performance under field conditions is usually less well understood. The wide variety of natural and manufactured products available in most cases precludes adequate peer-reviewed research to support claims about their effectiveness. This can lead to proliferation of unsubstantiated assertions of efficacy. This review highlights the lack of field-scale evidence of benefits for many biological amendments with potential to be used in agriculture. We propose complementary approaches of (i) laboratory- or glasshouse-scale research to understand modes of action, and (ii) targeted field-scale participatory research involving groups of farmers using on-farm trials as a forward pathway. Use of biological amendments to overcome soil constraints is expected to expand with intensification of agriculture and as a result of climate change. Therefore, information that enables farmers to discriminate among products that have different levels of effectiveness is necessary, and on-farm participatory research should contribute to addressing this need.
Highlights • AD patients have disturbed sleep, including increased sleep fragmentation. • Sleep and wake patterns in 5XFAD mice, a model of AD, were examined. • 5XFAD mice of both sexes were found to ...have reduced sleep bout lengths. • Female 5XFAD were more severely affected, and had reduced total sleep as well. • Sleep alterations in 5XFAD mice may be relevant to human AD sleep disturbances.
A land–sea surface warming ratio (or
φ
) that exceeds unity is a robust feature of both observed and modelled climate change. Interestingly, though climate models have differing values for
φ
, it ...remains almost time-invariant for a wide range of twenty-first century climate transient warming scenarios, while varying in simulations of the twentieth century. Here, we present an explanation for time-invariant land–sea warming ratio that applies if three conditions on radiative forcing are met: first, spatial variations in the climate forcing must be sufficiently small that the lower free troposphere warms evenly over land and ocean; second, the temperature response must not be large enough to change the global circulation to zeroth order; third, the temperature response must not be large enough to modify the boundary layer amplification mechanisms that contribute to making
φ
exceed unity. Projected temperature changes over this century are too small to breach the latter two conditions. Hence, the mechanism appears to show why both twenty-first century and time-invariant CO
2
forcing lead to similar values of
φ
in climate models despite the presence of transient ocean heat uptake, whereas twentieth century forcing—which has a significant spatially confined anthropogenic tropospheric aerosol component that breaches the first condition—leads to modelled values of
φ
that vary widely amongst models and in time. Our results suggest an explanation for the behaviour of
φ
when climate is forced by other regionally confined forcing scenarios such as geo-engineered changes to oceanic clouds. Our results show how land–sea contrasts in surface and boundary layer characteristics act in tandem to produce the land–sea surface warming contrast.
To propose standardized consensus definitions for important clinical endpoints in transcatheter aortic valve implantation (TAVI), investigations in an effort to improve the quality of clinical ...research and to enable meaningful comparisons between clinical trials. To make these consensus definitions accessible to all stakeholders in TAVI clinical research through a peer reviewed publication, on behalf of the public health.
Transcatheter aortic valve implantation may provide a worthwhile less invasive treatment in many patients with severe aortic stenosis and since its introduction to the medical community in 2002, there has been an explosive growth in procedures. The integration of TAVI into daily clinical practice should be guided by academic activities, which requires a harmonized and structured process for data collection, interpretation, and reporting during well-conducted clinical trials.
The Valve Academic Research Consortium established an independent collaboration between Academic Research organizations and specialty societies (cardiology and cardiac surgery) in the USA and Europe. Two meetings, in San Francisco, California (September 2009) and in Amsterdam, the Netherlands (December 2009), including key physician experts, and representatives from the U.S. Food and Drug Administration (FDA) and device manufacturers, were focused on creating consistent endpoint definitions and consensus recommendations for implementation in TAVI clinical research programs. Important considerations in developing endpoint definitions included: 1) respect for the historical legacy of surgical valve guidelines; 2) identification of pathophysiological mechanisms associated with clinical events; 3) emphasis on clinical relevance. Consensus criteria were developed for the following endpoints: mortality, myocardial infarction, stroke, bleeding, acute kidney injury, vascular complications, and prosthetic valve performance. Composite endpoints for TAVI safety and effectiveness were also recommended.
Although consensus criteria will invariably include certain arbitrary features, an organized multidisciplinary process to develop specific definitions for TAVI clinical research should provide consistency across studies that can facilitate the evaluation of this new important catheter-based therapy. The broadly based consensus endpoint definitions described in this document may be useful for regulatory and clinical trial purposes.
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