Animal migrations span the globe, involving immense numbers of individuals from a wide range of taxa. Migrants transport nutrients, energy, and other organisms as they forage and are preyed upon ...throughout their journeys. These highly predictable, pulsed movements across large spatial scales render migration a potentially powerful yet underappreciated dimension of biodiversity that is intimately embedded within resident communities. We review examples from across the animal kingdom to distill fundamental processes by which migratory animals influence communities and ecosystems, demonstrating that they can uniquely alter energy flow, food-web topology and stability, trophic cascades, and the structure of metacommunities. Given the potential for migration to alter ecological networks worldwide, we suggest an integrative framework through which community dynamics and ecosystem functioning may explicitly consider animal migrations.
Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular ...nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens probe, launched from the Cassini spacecraft, has made the first direct observations of the satellite's surface and lower atmosphere. Here we report direct atmospheric measurements from the Gas Chromatograph Mass Spectrometer (GCMS), including altitude profiles of the constituents, isotopic ratios and trace species (including organic compounds). The primary constituents were confirmed to be nitrogen and methane. Noble gases other than argon were not detected. The argon includes primordial 36Ar, and the radiogenic isotope 40Ar, providing an important constraint on the outgassing history of Titan. Trace organic species, including cyanogen and ethane, were found in surface measurements.
The movement of evidence-based practices (EBPs) into routine clinical usage is not spontaneous, but requires focused efforts. The field of implementation science has developed to facilitate the ...spread of EBPs, including both psychosocial and medical interventions for mental and physical health concerns.
The authors aim to introduce implementation science principles to non-specialist investigators, administrators, and policymakers seeking to become familiar with this emerging field. This introduction is based on published literature and the authors' experience as researchers in the field, as well as extensive service as implementation science grant reviewers. Implementation science is "the scientific study of methods to promote the systematic uptake of research findings and other EBPs into routine practice, and, hence, to improve the quality and effectiveness of health services." Implementation science is distinct from, but shares characteristics with, both quality improvement and dissemination methods. Implementation studies can be either assess naturalistic variability or measure change in response to planned intervention. Implementation studies typically employ mixed quantitative-qualitative designs, identifying factors that impact uptake across multiple levels, including patient, provider, clinic, facility, organization, and often the broader community and policy environment. Accordingly, implementation science requires a solid grounding in theory and the involvement of trans-disciplinary research teams. The business case for implementation science is clear: As healthcare systems work under increasingly dynamic and resource-constrained conditions, evidence-based strategies are essential in order to ensure that research investments maximize healthcare value and improve public health. Implementation science plays a critical role in supporting these efforts.
Limiting global warming to 1.5 or 2.0°C requires strong mitigation of anthropogenic greenhouse gas (GHG) emissions. Concurrently, emissions of anthropogenic aerosols will decline, due to coemission ...with GHG, and measures to improve air quality. However, the combined climate effect of GHG and aerosol emissions over the industrial era is poorly constrained. Here we show the climate impacts from removing present‐day anthropogenic aerosol emissions and compare them to the impacts from moderate GHG‐dominated global warming. Removing aerosols induces a global mean surface heating of 0.5–1.1°C, and precipitation increase of 2.0–4.6%. Extreme weather indices also increase. We find a higher sensitivity of extreme events to aerosol reductions, per degree of surface warming, in particular over the major aerosol emission regions. Under near‐term warming, we find that regional climate change will depend strongly on the balance between aerosol and GHG forcing.
Plain Language Summary
To keep within 1.5 or 2° of global warming, we need massive reductions of greenhouse gas emissions. At the same time, aerosol emissions will be strongly reduced. We show how cleaning up aerosols, predominantly sulfate, may add an additional half a degree of global warming, with impacts that strengthen those from greenhouse gas warming. The northern hemisphere is found to be more sensitive to aerosol removal than greenhouse gas warming, because of where the aerosols are emitted today. This means that it does not only matter whether or not we reach international climate targets. It also matters how we get there.
Key Points
Aerosol emission removal can warm the climate by more than 0.5°C
Key climate variables are more sensitive to aerosol removal than to GHG increase
Regional impacts of 1.5°C warming depend on the balance between aerosol and GHG forcing
•Resting-state alpha oscillations form time-periodic spatial patterns in a) continuous space and time, b) in the discrete microstate representation.•The oscillatory properties of microstate sequences ...are coded by the analytic phase of alpha oscillations and not by the analytic amplitude.•Over the course of 1-2 alpha cycles, the combination of quasi-static amplitude and periodic phase patterns indicate transient standing wave patterns.•Periodic phase patterns emerge from phase rotors, organized around a small number of phase singularities which are dynamic over time.•Pattern formation in resting-state alpha activity can be modelled by near-critical coupled oscillator lattices close to an Andronov-Hopf bifurcation.
Spatio-temporal patterns in electroencephalography (EEG) can be described by microstate analysis, a discrete approximation of the continuous electric field patterns produced by the cerebral cortex. Resting-state EEG microstates are largely determined by alpha frequencies (8-12 Hz) and we recently demonstrated that microstates occur periodically with twice the alpha frequency.
To understand the origin of microstate periodicity, we analyzed the analytic amplitude and the analytic phase of resting-state alpha oscillations independently. In continuous EEG data we found rotating phase patterns organized around a small number of phase singularities which varied in number and location. The spatial rotation of phase patterns occurred with the underlying alpha frequency. Phase rotors coincided with periodic microstate motifs involving the four canonical microstate maps. The analytic amplitude showed no oscillatory behaviour and was almost static across time intervals of 1-2 alpha cycles, resulting in the global pattern of a standing wave.
In n=23 healthy adults, time-lagged mutual information analysis of microstate sequences derived from amplitude and phase signals of awake eyes-closed EEG records showed that only the phase component contributed to the periodicity of microstate sequences. Phase sequences showed mutual information peaks at multiples of 50 ms and the group average had a main peak at 100 ms (10 Hz), whereas amplitude sequences had a slow and monotonous information decay. This result was confirmed by an independent approach combining temporal principal component analysis (tPCA) and autocorrelation analysis.
We reproduced our observations in a generic model of EEG oscillations composed of coupled non-linear oscillators (Stuart-Landau model). Phase-amplitude dynamics similar to experimental EEG occurred when the oscillators underwent a supercritical Hopf bifurcation, a common feature of many computational models of the alpha rhythm.
These findings explain our previous description of periodic microstate recurrence and its relation to the time scale of alpha oscillations. Moreover, our results corroborate the predictions of computational models and connect experimentally observed EEG patterns to properties of critical oscillator networks.
Cellular space charge polymer electrets significantly enlarge the basis of pyro- and piezoelectric as well as ferroic materials. Since the first review of the field has been published in this journal ...(R. Gerhard-Multhaupt, Less can be more: Holes in polymers lead to a new paradigm of piezoelectric materials for electret transducers, IEEE Trans. Dielectr. Electr. Insul. Vol.9, pp.850-859, 2002), progress has been achieved in the understanding, preparation and characterization of cellular space charge electrets. Advanced applications arise in stacked microphones, artificial sonar systems, and in the combination of piezo- and ferroelectrets with flexible electronics. In the present survey an update of the developments since 2002 is provided
Drug delivery of poorly soluble drugs in form amorphous solid dispersions (ASDs) is an appealing method to increase in vivo bioavailability. For rational formulation design, a mechanistic ...understanding of the impact of surfactants on the performance of ASD-based formulations is therefore of importance.
In this study, we used hot-melt extrusion to prepare ASDs composed of the model drug substance efavirenz with hydroxypropyl methylcellulose phthalate (HPMCP) as the base polymer, and surfactants. Molecular dynamics simulations and in vitro dissolution studies were used to investigate formation and drug release from polymer vesicles, and their ability to maintain a supersaturation state as a function of surfactant composition.
It was possible to identify main factors regulating particle formation and to modify dissolution profiles with different excipient compositions. Animal studies in the rat, in combination with physiologically based pharmacokinetic modeling, demonstrated enhanced drug absorption from formed vesicles. The surfactant composition in the ASD had a direct influence on the morphology of these vesicles, as well as kinetics of drug release, and, therefore, the oral bioavailability. ASDs, prepared by hot-melt extrusion method, were optimized for dissolution and adsorption rates increase.
Our findings contribute to a better understanding of dissolution behavior of ASDs with respect to the function of surfactants, aiming to facilitate a rational formulation development and an accelerated transition from in vitro systems to in vivo applications.
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