Analysis of Northern Hemisphere spring terrestrial snow cover extent (SCE) from the NOAA snow chart Climate Data Record (CDR) for the April to June period (when snow cover is mainly located over the ...Arctic) has revealed statistically significant reductions in May and June SCE. Successive records for the lowest June SCE have been set each year for Eurasia since 2008, and in 3 of the past 5 years for North America. The rate of loss of June snow cover extent between 1979 and 2011 (−17.8% decade−1) is greater than the loss of September sea ice extent (−10.6% decade−1) over the same period. Analysis of Coupled Model Intercomparison Project Phase 5 (CMIP5) model output shows the marked reductions in June SCE observed since 2005 fall below the zone of model consensus defined by +/−1 standard deviation from the multi‐model ensemble mean.
Key Points
N. Hemisphere spring snow cover extent reductions since 1967 are significant
Rate of June snow loss exceeds the rate of September sea ice loss (1979‐2011)
Snow reductions since 2005 exceed an ensemble of CMIP5 simulations
A clinical tool that can diagnose psychiatric illness using functional or structural magnetic resonance (MR) brain images has the potential to greatly assist physicians and improve treatment ...efficacy. Working toward the goal of automated diagnosis, we propose an approach for automated classification of ADHD and autism based on histogram of oriented gradients (HOG) features extracted from MR brain images, as well as personal characteristic data features. We describe a learning algorithm that can produce effective classifiers for ADHD and autism when run on two large public datasets. The algorithm is able to distinguish ADHD from control with hold-out accuracy of 69.6% (over baseline 55.0%) using personal characteristics and structural brain scan features when trained on the ADHD-200 dataset (769 participants in training set, 171 in test set). It is able to distinguish autism from control with hold-out accuracy of 65.0% (over baseline 51.6%) using functional images with personal characteristic data when trained on the Autism Brain Imaging Data Exchange (ABIDE) dataset (889 participants in training set, 222 in test set). These results outperform all previously presented methods on both datasets. To our knowledge, this is the first demonstration of a single automated learning process that can produce classifiers for distinguishing patients vs. controls from brain imaging data with above-chance accuracy on large datasets for two different psychiatric illnesses (ADHD and autism). Working toward clinical applications requires robustness against real-world conditions, including the substantial variability that often exists among data collected at different institutions. It is therefore important that our algorithm was successful with the large ADHD-200 and ABIDE datasets, which include data from hundreds of participants collected at multiple institutions. While the resulting classifiers are not yet clinically relevant, this work shows that there is a signal in the (f)MRI data that a learning algorithm is able to find. We anticipate this will lead to yet more accurate classifiers, over these and other psychiatric disorders, working toward the goal of a clinical tool for high accuracy differential diagnosis.
•Techno-economic analyses of thermochemical cellulosic biofuel pathways are reviewed.•The results of the techno-economic analyses are compared.•Differences in assumptions result in a wide range of ...financial result values.•The importance of justifying assumptions and analyzing uncertainty is discussed.
Recent advances in the thermochemical processing of biomass have resulted in efforts to commercialize several cellulosic biofuel pathways. Until commercial-scale production is achieved, however, techno-economic analysis is a useful methodology for quantifying the economic competitiveness of these pathways with petroleum, providing one indication of their long-term feasibility under the U.S. revised Renewable Fuel Standard. This review paper covers techno-economic analyses of thermochemical cellulosic biofuel pathways in the open literature, discusses and compares their results, and recommends the adoption of additional analytical methodologies that will increase the value of future pathway analyses.
A
bstract
Using a heavy-mass effective field theory (HEFT), we study gravitational-wave emission in the scattering of two spinless black holes or neutron stars of arbitrary masses at next-to-leading ...order in the Post-Minkowskian expansion. We compute the contributions to the one-loop scattering amplitude with four scalars and one graviton which are relevant to the calculation of the waveforms, also presenting expressions of classical tree-level amplitudes with four scalars and up to two radiated gravitons. The latter are obtained using a novel on-shell recursion relation for classical amplitudes with four scalars and an arbitrary number of gravitons. Our one-loop five-point amplitude is expressed in terms of a single family of master integrals with the principal value prescription for linearised massive propagators, which we evaluate using differential equations. In our HEFT approach, soft/heavy-mass expansions of complete integrands are avoided, and all hyper-classical iterations and quantum corrections are dropped at the diagrammatic level, thereby computing directly contributions to classical physics. Our result exhibits the expected factorisation of infrared divergences, the correct soft limits, and highly nontrivial cancellations of spurious poles. Finally, using our amplitude result we compute numerically the corresponding next-to-leading corrections to the spectral waveforms and the far-field time-domain waveforms using the Newman-Penrose scalar Ψ
4
.
The single largest risk factor for etiology of neurodegenerative diseases like Alzheimer’s disease is increased age. Therefore, understanding the changes that occur as a result of aging is central to ...any possible prevention or cure for such conditions. Microglia, the resident brain glial population most associated with both protection of neurons in health and their destruction is disease, could be a significant player in age related changes. Microglia can adopt an aberrant phenotype sometimes referred to either as dystrophic or senescent. While aged microglia have been frequently identified in neurodegenerative diseases such as Alzheimer’s disease, there is no conclusive evidence that proves a causal role. This has been hampered by a lack of models of aged microglia. We have recently generated a model of senescent microglia based on the observation that all dystrophic microglia show iron overload. Iron‐overloading cultured microglia causes them to take on a senescent phenotype and can cause changes in models of neurodegeneration similar to those observed in patients. This review considers how this model could be used to determine the role of senescent microglia in neurodegenerative diseases.
The most important risk factor for neurodegenerative diseases like Alzheimer’s disease is aging. While the potential role aberrant microglia play in neurodegeneration has been studied for some time, new evidence suggests that that microglial aging might be more important. When microglia become senescent they lose many of their supportive roles and compromise neuronal survival. This review focuses on senescent microglia. New models of senescent microglia could advance study of aging and neurodegeneration.
Although a growing body of evidence suggests that giving to (helping) others is linked reliably to better health and longevity for the helper, little is known about causal mechanisms. In the present ...paper we use a recently developed model of caregiving motivation to identify possible neurophysiological mechanisms. The model describes a mammalian neurohormonal system that evolved to regulate maternal care, but over time may have been recruited to support a wide variety of helping behaviors in humans and other social animals. According to the model, perception of need or distress in others activates caregiving motivation, which in turn, can facilitate helping behavior. Motivational regulation is governed by the medial preoptic area of the hypothalamus, interacting with certain other brain regions, hormones, and neuromodulators (especially oxytocin and progesterone). Consideration of neurohormonal circuitry and related evidence raises the possibility that it is these hormones, known to have stress-buffering and restorative properties, that are responsible, at least in part, for health and longevity benefits associated with helping others.
The passage of time is tracked by counting oscillations of a frequency reference, such as Earth's revolutions or swings of a pendulum. By referencing atomic transitions, frequency (and thus time) can ...be measured more precisely than any other physical quantity, with the current generation of optical atomic clocks reporting fractional performance below the 10
level
. However, the theory of relativity prescribes that the passage of time is not absolute, but is affected by an observer's reference frame. Consequently, clock measurements exhibit sensitivity to relative velocity, acceleration and gravity potential. Here we demonstrate local optical clock measurements that surpass the current ability to account for the gravitational distortion of space-time across the surface of Earth. In two independent ytterbium optical lattice clocks, we demonstrate unprecedented values of three fundamental benchmarks of clock performance. In units of the clock frequency, we report systematic uncertainty of 1.4 × 10
, measurement instability of 3.2 × 10
and reproducibility characterized by ten blinded frequency comparisons, yielding a frequency difference of -7 ± (5)
± (8)
× 10
, where 'stat' and 'sys' indicate statistical and systematic uncertainty, respectively. Although sensitivity to differences in gravity potential could degrade the performance of the clocks as terrestrial standards of time, this same sensitivity can be used as a very sensitive probe of geopotential
. Near the surface of Earth, clock comparisons at the 1 × 10
level provide a resolution of one centimetre along the direction of gravity, so the performance of these clocks should enable geodesy beyond the state-of-the-art level. These optical clocks could further be used to explore geophysical phenomena
, detect gravitational waves
, test general relativity
and search for dark matter
.
Corporate transparency reduces information asymmetries between firms and capital markets but increases the costs associated with information leakage to competitors. We explore how a country’s ...information environment affects innovation, an activity characterized by high information asymmetries and potentially severe proprietary costs. Studying both long-run cross-country differences in the availability of firm-specific information to corporate outsiders, as well as quasi-experimental shocks to the information environment following transparency-enhancing security market reforms, we document significantly higher rates of R&D and patenting in richer information environments. The effects of transparency are strongest in industries that rely on external equity rather than bank debt, indicating that transparency facilitates innovation by reducing the information costs associated with arm’s-length financing. In contrast, transparency has no impact on physical capital accumulation, consistent with fewer information asymmetries in tangible assets. An economy’s information environment has important but heterogeneous effects on the nature and extent of real economic activity.
This paper was accepted by Shiva Rajgopal, accounting.
The most common form of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting adult motor neurons, is caused by dominant mutations in the ubiquitously expressed Cu-Zn Superoxide ...dismutase (SOD1). In chimeric mice that are mixtures of normal and SOD1 mutant-expressing cells, toxicity to motor neurons is shown to require damage from mutant SOD1 acting within nonneuronal cells. Normal motor neurons in SOD1 mutant chimeras develop aspects of ALS pathology. Most important, nonneuronal cells that do not express mutant SOD1 delay degeneration and significantly extend survival of mutant-expressing motor neurons.
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