Pencil-beam Doppler scatterometers are a promising remote sensing tool for measuring ocean vector winds and currents from space. While several point designs exist in the literature, these designs ...have been constrained by the hardware they inherited, and the design is sub-optimal. Here, guidelines to optimize the design of these instruments starting from the basic sensitivity equations are presented. Unlike conventional scatterometers or pencil-beam imagers, appropriate sampling of the Doppler spectrum and optimizing the radial velocity error lead naturally to a design that incorporates a pulse-to-pulse separation and pulse length that vary with scan angle. Including this variation can improve radial velocity performance significantly and the optimal selection of system timing and bandwidth is derived. Following this, optimization of the performance based on frequency, incidence angle, antenna length, and spatial sampling strategy are considered. It is shown that antenna length influences the performance most strongly, while the errors depend only on the square root of the transmit power. Finally, a set of example designs and associated performance are presented.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The Spanish Meteorological Agency (AEMET) is responsible for the elaboration of downscaled climate projections over Spain to feed the Second National Plan of Adaptation to Climate Change (PNACC‐2). ...The main objective of this article is to establish a comparison among five statistical downscaling methods developed at AEMET: (1) Analog, (2) Regression, (3) Artificial Neural Networks, (4) Support Vector Machines and (5) Kernel Ridge Regression. This comparison has been carried out under present conditions and with perfect predictors, based on the framework established by the VALUE network, in particular, on its perfect predictor experiment. In this experiment, we evaluate the marginal aspects of the distributions of daily maximum/minimum temperatures and daily accumulated precipitation analysed by seasons, on a high resolution observational grid (0.05°) over mainland Spain and the Balearic Islands. This is the first of a set of three experiments aimed to allow us to decide which methods, and under what configuration, is more appropriate for the generation of downscaled climate projections over our region. For maximum/minimum temperatures, all methods display a similar behaviour. They capture very satisfactorily the mean values although slight biases are detected on the extremes. In general, results for maximum temperature appear to be more accurate than for minimum temperature, and the nonlinear methods display certain added value. For precipitation, remarkable differences are found among all methods. Most of the methods are capable of reproducing the total precipitation amount quite satisfactorily, whereas other aspects such as intense precipitations and the precipitation occurrence are captured with more accuracy by the Analog method.
Relative bias (%) for PRCPTOT (upper row), R95p (middle row) and R01 (lower row) for precipitation by seasons: no downscaling (grey), six Analog methods (red and orange), three Generalized Linear Models (blue) and three Machine Learning techniques (green). A red asterisk indicates that values lie outside the plotted range.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Vogt-Koyanagi-Harada disease (VKHD) is a rare granulomatous inflammatory disease that affects pigmented structures, such as eye, inner ear, meninges, skin and hair. This disease is mainly a Th1 ...lymphocyte mediated aggression to melanocytes after a viral trigger in the presence of HLA-DRB1*0405 allele. The absence of ocular trauma or previous intraocular surgery sets VKHD appart from sympathetic ophthalmia, its main differential diagnosis. The disease has an acute onset of bilateral blurred vision with hyperemia preceded by flu-like symptoms. The acute uveitic stage is characterized by a diffuse choroiditis with serous retinal detachment and optic disc hyperemia and edema. Fluorescein angiography in this phase demonstrates multiple early hyperfluorescent points. After the acute uveitic stage, ocular and integumentary system pigmentary changes may appear. Ocular findings may be accompanied by lymphocytic meningitis, hearing impairment and/or tinnitus in a variable proportion of patients. Prompt diagnosis followed by early, aggressive and long-term treatment with high-dose corticosteroids is most often ensued by good visual outcomes. However, some patients may experience chronic uveal inflammation with functional eye deterioration. The current review discusses the general features of VKHD, including epidemiology, classification into categories, differential diagnosis and current therapeutic approaches.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The positive effect of information and communication technologies (ICT) on trade between countries has been widely studied in the literature, but how ICT impacts regional trade is limited due to the ...lack of regional trade data. In this paper, we test whether broadband, as a proxy for ICT, increases bilateral trade at the regional level in Europe. We use a novel regional trade database of European Union regions and estimate an origin–destination flow gravity model for 2007 and 2010, accounting for spatial dependence among trade flows. Our results indicate that broadband is positive and significant in explaining trade patterns between European regions during both time periods.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, ODKLJ, OILJ, PILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Machine learning is a growing field of research with many applications. It provides a series of techniques able to solve complex nonlinear problems, and that has promoted their application for ...statistical downscaling. Intercomparison exercises with other classical methods have so far shown promising results. Nevertheless, many evaluation studies of statistical downscaling methods neglect the analysis of their extrapolation capability. In this study, we aim to make a wakeup call to the community about the potential risks of using machine learning for statistical downscaling of climate change projections. We present a set of three toy experiments, applying three commonly used machine learning algorithms, two different implementations of artificial neural networks and a support vector machine, to downscale daily maximum temperature, and comparing them with the classical multiple linear regression. We have tested the four methods in and out of their calibration range, and have found how the three machine learning techniques can perform poorly under extrapolation. Additionally, we have analysed the impact of this extrapolation issue depending on the degree of overlapping between the training and testing datasets, and we have found very different sensitivities for each method and specific implementation.
Standardised T850 versus observed (grey) downscaled maximum temperature (°C) by multiple linear regression (blue), artificial neural network with relu activation function (orange) artificial neural network with logistic activation function (red) and support vector regression (green). Pink background indicates extrapolation beyond the calibration range.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Changes in glycosylation during tumour progression are a key hallmark of cancer. One of the glycan moieties generally overexpressed in cancer are sialic acids, which can induce immunomodulatory ...properties via binding to Siglec receptors. We here show that Pancreatic Ductal Adenocarcinoma (PDAC) tumour cells present an increased sialylation that can be recognized by Siglec-7 and Siglec-9 on myeloid cells. We identified the expression of the α2,3 sialyltransferases ST3GAL1 and ST3GAL4 as main contributor to the synthesis of ligands for Siglec-7 and Siglec-9 in tumour cells. Analysing the myeloid composition in PDAC, using single cell and bulk transcriptomics data, we identified monocyte-derived macrophages as contributors to the poor clinical outcome. Tumour-derived sialic acids dictate monocyte to macrophage differentiation via signalling through Siglec-7 and Siglec-9. Moreover, triggering of Siglec-9 in macrophages reduce inflammatory programmes, while increasing PD-L1 and IL-10 expression, illustrating that sialic acids modulate different myeloid cells. This work highlights a critical role for sialylated glycans in controlling immune suppression and provides new potential targets for cancer immunotherapy in PDAC.
The elevation of the ocean surface has been measured for over two decades from spaceborne altimeters. However, existing altimeter measurements are not adequate to characterize the dynamic variations ...of most inland water bodies, nor of ocean eddies at scales of less than about 100 km, notwithstanding that such eddies play a key role in ocean circulation and climate change. For terrestrial hydrology, in situ and spaceborne measurements of water surface elevation form the basis for estimates of water storage change in lakes, reservoirs, and wetlands, and of river discharge. However, storage in most inland water bodies, e.g., millions of Arctic lakes, is not readily measured using existing technologies. A solution to the needs of both surface water hydrology and physical oceanography communities is the measurement of water elevations along rivers, lakes, streams, and wetlands and over the ocean surface using swath altimetry. The proposed surface water and ocean topography (SWOT) mission will make such measurements. The core technology for SWOT is the Ka-band radar interferometer (KaRIN), which would achieve spatial resolution on the order of tens of meters and centimetric vertical precision when averaged over targets of interest. Average revisit times will depend upon latitude, with two to four revisits at low to mid latitudes and up to ten revisits at high latitudes per \sim 20-day orbit repeat period.
A multidimensional approach was applied to analyze trends of the Cuban scientific output in the context of the 21 Latin American countries exceeding two million inhabitants. Output performance for ...each country were compared. The following parameters were analyzed: output and journals indexed at Scopus (SCImago stats, 1996–2018) and the Web of Science Core Collection (1996–2019), journals covered by SciELO, academic journals registered at Latindex, and the number of serials registered by the ISSN International Centre. The comparative elements include: Web of Science vs. Scopus annual output and by cumulative frequency, share of academic journal output by country vs. total output, output in national journals and document typologies. It was shown that either annual or cumulative, ranking in the LAC region has been quite stable despite few changes during 2015–2019. The rise of Brazil’s output either in foreign or Brazilian journals increased its cumulative regional contribution by 11.37% from 1996 to 2018 and equivalently stabilized or decreased the relative regional contribution indexes for most countries either cumulative (positive change only for Mexico) or annual (positive changes for Colombia, Ecuador, Chile and Peru). In spite of its 11th position in population and 10th position in GDP, Cuba ranked among the first eight most productive countries (ranked 7th in total documents), quantitatively outperforming LAC countries with more GDP and population. Its ranking was highly influenced by Cuban journals’ output. Some considerations are provided for a more balanced analysis of scientific output in relation to socio-economic and database indexing aspects.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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