Wide‐swath spaceborne Doppler scatterometry is a promising technique for the simultaneous measurement of global ocean surface winds and currents. The technique has been proven from airborne ...platforms, and here we use the lessons learned to examine a range of implications for a spaceborne system. We use a Doppler scatterometer simulator and a state‐of‐the‐art global circulation model to generate surface current measurements and their random errors. We find that a feasible instrument could measure 5 km gridded surface currents with typical random errors between 10 and 25 cm/s. For higher wind speeds, the random error in surface current decreases logarithmically. This level of accuracy allows for the computation of surface current relative vorticity and horizontal divergence with typical wavelength resolutions of 15–30 and 25–60 km, respectively. Unlike previous studies, we find that these measurements do not require multiday averaging, opening up new avenues for monitoring global ocean circulation.
Plain Language Summary
Our understanding of the ocean, the atmosphere, and the Earth system as a whole has been profoundly bettered by the global perspective of space‐based sensors. For decades, radar scatterometers have measured global ocean winds from space, contributing significantly to our scientific understanding of the atmosphere and improving forecast models. With a similar instrument, and the addition of “Doppler” capability, a Doppler scatterometer can measure ocean winds and ocean surface currents simultaneously, which opens new avenues to understanding the ocean, the atmosphere, and how they interact. This type of instrument has been successfully built and proven to work on airborne platforms but has yet to be implemented on a satellite. In this work, we have simulated the measurements of a spaceborne Doppler scatterometer to understand the oceanic scales that such an instrument might be able to observe. We find that ocean currents and their derivatives could be measured at scales better than 30 km. This enables the study of many currently unobserved ocean processes, including the vertical circulation of the ocean and the transport of plastics, kinetic energy, heat, and gasses.
Key Points
Doppler scatterometry (WaCM) could measure simultaneous surface winds and currents globally
Ocean surface currents are resolved at scales of 10 km in most locations for wind speeds greater than 5 m/s without temporal averaging
Typical effective wavelength resolution for surface current relative vorticity and divergence are 15 km and 25 km without temporal averaging
We propose a fully covariant model for smeared particle detectors in quantum field theory in curved spacetimes. We show how effects related to accelerated motion of the detector and the curvature of ...spacetime influence the way different observers assign an interaction Hamiltonian between the detector and the field. The fully covariant formulation explicitly leaves the physical predictions of the theory invariant under general coordinate transformations, hence providing a description of particle detector models (e.g., Unruh-DeWitt detectors, models for the light-matter interaction, etc.) that is suitable for arbitrary trajectories in general spacetime backgrounds.
In this review, we discuss the biology and beneficial effects of plant endophytes on host plants. The current explanation of endophyte protection (defensive mutualism) of host plants is based on the ...secondary metabolites (alkaloids) with antiherbivore properties produced by the symbiotic association between host plant and endophytes. We propose an alternative explanation of the mechanism of host protection through enhanced stress tolerance to oxidative stress. Several studies have demonstrated the production of different compounds (phenolics) with antioxidant capacity in endophyte-infected plants. Endophytes may also produce mannitol, other carbohydrates and small molecules (proline) with antioxidant capacity. We suggest that enhanced antioxidant production by symbiotic plants may be the result of the production of reactive oxygen species (ROS) by endophytes. In turn, symbiotic plants are protected from oxidative stress produced by plant diseases, droughts, heavy metals and other oxidative stressors by the production of antioxidants. We also discuss the lichen symbiosis and evaluate whether management of ROS also plays a role in this defensive mutualism. Future experiments are needed to evaluate the hypothesis that antioxidants are responsible for enhanced stress tolerance in endophyte-infected plants.
Pollution in the form of litter in the natural environment is one of the great challenges of our times. Automated litter detection can help assess waste occurrences in the environment. Different ...machine learning solutions have been explored to develop litter detection tools, thereby supporting research, citizen science, and volunteer clean-up initiatives. However, to the best of our knowledge, no work has investigated the performance of state-of-the-art deep learning object detection approaches in the context of litter detection. In particular, no studies have focused on the assessment of those methods aiming their use in devices with low processing capabilities, e.g., mobile phones, typically employed in citizen science activities. In this paper, we fill this literature gap. We performed a comparative study involving state-of-the-art CNN architectures (e.g., Faster RCNN, Mask-RCNN, EfficientDet, RetinaNet and YOLO-v5), two litter image datasets and a smartphone. We also introduce a new dataset for litter detection, named PlastOPol, composed of 2418 images and 5300 annotations. The experimental results demonstrate that object detectors based on the YOLO family are promising for the construction of litter detection solutions, with superior performance in terms of detection accuracy, processing time, and memory footprint.
There is mounting evidence to suggest aberrant astrocytic function in depression and suicide. Independent studies have reported astrocytic abnormalities in certain brain regions, but it remains ...unclear whether this is a brain-wide phenomenon. The present study examined this question by measuring glial fibrillary acidic protein (GFAP) expression in postmortem brain samples from suicide completers and matched non-psychiatric controls. Suicide completers were selected based on their recent characterization as low GFAP expressors in the prefrontal cortex, (Brodmann areas 8/9 and 10). Real-time PCR and immunoblotting were used to measure GFAP gene expression and protein levels in BA4 (primary motor cortex), BA17 (primary visual cortex), cerebellar cortex, mediodorsal thalamus and caudate nucleus. We found downregulation of GFAP mRNA and protein in the mediodorsal thalamus and caudate nucleus of depressed suicides compared with controls, whereas GFAP expression in other brain regions was similar between groups. Furthermore, a regional comparison including all samples revealed that GFAP expression in both subcortical regions was, on average, between 11- and 15-fold greater than in cerebellum and neocortex. Examining astrocyte morphology by immunohistochemistry showed that astrocytes in both thalamus and caudate displayed larger cell bodies and extended more ramified processes across larger domains than the previously described cortical astrocytes. This study reveals that astrocytic abnormalities are not brain wide and suggests that they are restricted to cortical and subcortical networks known to be affected in mood disorders. Additionally, our results show a greater diversity in human astrocytic phenotypes than previously thought.
Discrete element method (DEM) has achieved considerable success on simulating complex granular material behaviours. One of the key challenges of DEM simulations is how to describe particles with ...realistic geometries. Many shape description methods have been developed including sphere-clustering, polyhedrons, sphero-polyhedrons, superquadric particles to name a few. However, to model general shaped particles with round features , these techniques are either introducing artificial surface roughness or are limited to a few regular shapes. Here we proposed a metaball based DEM where the metaball equation is used to describe particle shapes. Because of its flexibility on choosing control points in the metaball equation, many complex shaped particles can be modelled within this framework. The particle collision is handled by solving an optimization problem. A Newton–Raphson method based algorithm of finding the closest points for metaball DEM is developed accordingly. Using 3D printed particles, the proposed scheme is validated by comparing the simulated ran-out distance with granular column collapses experimental results. The model is further applied to study shape effects on vibration induced segregations. It is shown that the proposed metaball DEM can capture shape influence which may crucial in many engineering and science applications.
We present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band ...light curves of SN 2007on and SN 2011iv are characterised by Δm15 (B) decline-rate values of 1.96 mag and 1.77 mag, respectively. Although they have similar decline rates, their peak B- and H-band magnitudes differ by ~ 0.60 mag and ~0.35 mag, respectively. After correcting for the luminosity vs. decline rate and the luminosity vs. colour relations, the peak B-band and H-band light curves provide distances that differ by ~ 14% and ~ 9%, respectively. These findings serve as a cautionary tale for the use of transitional SNe Ia located in early-type hosts in the quest to measure cosmological parameters. Interestingly, even though SN 2011iv is brighter and bluer at early times, by three weeks past maximum and extending over several months, its B − V colour is 0.12 mag redder than that of SN 2007on. To reconcile this unusual behaviour, we turn to guidance from a suite of spherical one-dimensional Chandrasekhar-mass delayed-detonation explosion models. In this context, 56Ni production depends on both the so-called transition density and the central density of the progenitor white dwarf. To first order, the transition density drives the luminosity–width relation, while the central density is an important second-order parameter. Within this context, the differences in the B − V colour evolution along the Lira regime suggest that the progenitor of SN 2011iv had a higher central density than SN 2007on.
Osteoporosis is a systemic skeletal disease characterized by low bone mineral density (BMD) and has been considered a risk factor for periodontal disease. The aim of this systematic review and ...meta-analysis was to verify the scientific evidence for the association of periodontal attachment loss with low BMD in postmenopausal women. A systematic search of the literature was performed in databases until August 2016, in accordance with Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Eligibility criteria included studies that compared clinical attachment loss (CAL) between postmenopausal women with low and normal BMD. Studies using similar methodology, with lower and higher risk of bias, were pooled into 3 different meta-analyses to compare CAL among women with normal BMD, osteoporosis, and osteopenia. In the first meta-analysis, mean CAL was compared among groups. In the other 2 meta-analyses, the mean percentages of sites with CAL ≥4 mm and ≥6 mm were respectively compared among groups. From 792 unique citations, 26 articles were selected for the qualitative synthesis. Eleven of the studies were appraised as presenting low risk of bias, and the association between low BMD and CAL was observed in 10 of these studies. Thirteen cross-sectional articles were included in the meta-analysis for osteoporosis and 9 in the osteopenia analysis. Women with low BMD presented greater mean CAL than those with normal BMD (osteoporosis = 0.34 mm 95% confidence interval (CI), 0.20–0.49, P < 0.001; osteopenia = 0.07 mm 95% CI, 0.01–0.13, P = 0.02). Only studies with lower risk of bias were available for the analysis of CAL severity. Women with low BMD presented more severe attachment loss, represented as mean percentage of sites with CAL ≥4 mm (osteoporosis = 3.04 95% CI, 1.23–4.85, P = 0.001; osteopenia = 1.74 95% CI, 0.36–3.12, P = 0.01) and CAL ≥6 mm (osteoporosis = 5.07 95% CI, 2.74–7.40, P < 0.001). This systematic review and meta-analysis indicates that postmenopausal women with osteoporosis or osteopenia may exhibit greater CAL compared with women with normal BMD.
Introduction
Obsessive-compulsive disorder (OCD) is a clinical syndrome whose hallmarks are excessive, anxiety-evoking thoughts and compulsive behaviours that are generally recognized as ...unreasonable, but which cause significant distress and impairment. OCD may also occur in the context of other neuropsychiatric disorders, most commonly other anxiety and mood disorders. The question remains as to whether these combinations of disorders should be regarded as independent, cooccurring disorders or as different manifestations of an incompletely understood constellation of OCD spectrum disorders with a common aetiology.
Objectives
To review critically whether there is a robust basis for the concept of an obsessive–compulsive (OC) spectrum of disorders, and if so, which disorders should be included.
Methods
Literature review performed on PubMed and Google Scholar databases, using the keywords “obsessive–compulsive disorder”, “obsessive–compulsive spectrum”, “body dysmorphic disorder”, “hypochondriasis”, “trichotillomania”, “psychiatry”.
Results
Obsessive–compulsive disorder (OCD) itself is a heterogeneous condition or group of conditions, and this needs to be appreciated in any articulation of a ‘spectrum’ of OC disorders. The basis for ‘membership’ of the spectrum is inconsistent and varied, with varying level of support for inclusion in the putative spectrum.
Conclusions
A more fruitful approach may be to consider behaviours and dimensions in OCD and OC spectrum disorders, and that this should be encompassed in further developments of the OC spectrum model.
Disclosure of Interest
None Declared
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