Tensors are widely used to represent multiway arrays of data. The recovery of missing entries in a tensor has been extensively studied, generally under the assumption that entries are missing completely at random (MCAR). However, in most practical settings, observations are missing not at random (MNAR): the probability that a given entry is observed (also called the propensity) may depend on other entries in the tensor or even on the value of the missing entry. In this paper, we study the problem of completing a partially observed tensor with MNAR observations, without prior information about the propensities. To complete the tensor, we assume that both the original tensor and the tensor of propensities have low multilinear rank. The algorithm first estimates the propensities using a convex relaxation and then predicts missing values using a higher-order SVD approach, reweighting the observed tensor by the inverse propensities. We provide finite-sample error bounds on the resulting complete tensor. Numerical experiments demonstrate the effectiveness of our approach.

By the end of July 2020, Kenya h ad reported only 341 deaths and ∼20,000 cases of COVID-19. This is in marked contrast to the tens of thousands of deaths reported in many higher-income countries. The true extent of COVID-19 in the community was unknown and likely to be higher than reports indicated. Uyoga et al. found an overall seroprevalence among blood donors of 4.3%, peaking in 35- to 44-year-old individuals (see the Perspective by Maeda and Nkengasong). The low mortality can be partly explained by the steep demographics in Kenya, where less than 4% of the population is 65 or older. These circumstances combine to result in Kenyan hospitals not currently being overwhelmed by patients with respiratory distress. However, the imposition of a strict lockdown in this country has shifted the disease burden to maternal and child deaths as a result of disruption to essential medical services. Science , this issue p. [79][1]; see also p. [27][2] The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Africa is poorly described. The first case of SARS-CoV-2 in Kenya was reported on 12 March 2020, and an overwhelming number of cases and deaths were expected, but by 31 July 2020, there were only 20,636 cases and 341 deaths. However, the extent of SARS-CoV-2 exposure in the community remains unknown. We determined the prevalence of anti–SARS-CoV-2 immunoglobulin G among blood donors in Kenya in April–June 2020. Crude seroprevalence was 5.6% (174 of 3098). Population-weighted, test-performance-adjusted national seroprevalence was 4.3% (95% confidence interval, 2.9 to 5.8%) and was highest in urban counties Mombasa (8.0%), Nairobi (7.3%), and Kisumu (5.5%). SARS-CoV-2 exposure is more extensive than indicated by case-based surveillance, and these results will help guide the pandemic response in Kenya and across Africa. [1]: /lookup/doi/10.1126/science.abe1916 [2]: /lookup/doi/10.1126/science.abf8832

Subsidence, the lowering of Earth's land surface, is a potentially destructive hazard that can be caused by a wide range of natural or anthropogenic triggers but mainly results from solid or fluid mobilization underground. Subsidence due to groundwater depletion ([ 1 ][1]) is a slow and gradual process that develops on large time scales (months to years), producing progressive loss of land elevation (centimeters to decimeters per year) typically over very large areas (tens to thousands of square kilometers) and variably affects urban and agricultural areas worldwide. Subsidence permanently reduces aquifer-system storage capacity, causes earth fissures, damages buildings and civil infrastructure, and increases flood susceptibility and risk. During the next decades, global population and economic growth will continue to increase groundwater demand and accompanying groundwater depletion ([ 2 ][2]) and, when exacerbated by droughts ([ 3 ][3]), will probably increase land subsidence occurrence and related damages or impacts. To raise awareness and inform decision-making, we evaluate potential global subsidence due to groundwater depletion, a key first step toward formulating effective land-subsidence policies that are lacking in most countries worldwide. A large-scale systematic literature review reveals that during the past century, land subsidence due to groundwater depletion occurred at 200 locations in 34 countries [see supplementary materials (SM)]. However, subsidence extent is only known for one-third of these records, information on the impacts is scarce, and mitigation measures were implemented only in a few locations. In China, widespread subsidence affects cities developed in the main sedimentary basins. In Indonesia, coastal subsidence in Jakarta is so severe that government authorities are planning to move the capital to the island of Borneo. In Japan, subsidence affected several cities during the 20th century, including more than 4 m of subsidence in Tokyo, before groundwater management practices mitigated further subsidence. Iran currently hosts some of the fastest-sinking cities in the world (25 cm year--1) because of unregulated groundwater pumping. In Europe, the greatest impact of subsidence occurs in the Netherlands, where subsidence is primarily responsible for placing 25% of the country below the mean sea level and increasing the flooding risk. Subsidence in the Po River Plain in Italy started during the second half of the 20th century and currently threatens 30% of the Italian population, contributing to recurrent coastal flooding during extreme high tides in Venice. In North America, intense groundwater depletion triggers subsidence from California's Central Valley, with as much as 9 m of subsidence in the past century, to the Atlantic and Gulf of Mexico coastal plains in the United States, where subsidence is increasing flooding risk. In México, subsidence rates are among the highest worldwide (as much as 30 cm year-1), affecting small structurally controlled intermontane basins where the main urban centers developed, causing an important but unaccounted economic impact. Spatial analysis of subsidence locations identified in our global database (see SM) reveals that subsidence has preferentially occurred in very flat areas where unconsolidated sediments accumulated in alluvial basins or coastal plains, and where urban or agricultural areas developed in temperate or arid climates characterized by prolonged dry periods. Land subsidence has generally occurred in water-stressed basins, where the combination of groundwater withdrawal and natural groundwater discharge outpaced groundwater recharge, resulting in groundwater storage losses, groundwater depletion, and compaction of susceptible aquifer systems. In the affected basins, land subsidence mainly occurred in highly populated areas, with half of documented occurrences in areas susceptible to flooding. In coastal zones, the combined effects of absolute sea-level rise and land subsidence contribute to relative sea-level rise ([ 4 ][4]). The contribution from land subsidence may exceed the contribution from absolute sea-level rise by a factor of 10 or more and could be especially critical for 21% of the geographic locations identified in our database, where land elevation is less than 1 m above the mean sea level. On the basis of the spatial analysis findings, a global model is proposed to combine the main variables influencing subsidence to identify environmental settings favoring land subsidence and the anthropogenic factors leading to groundwater depletion (see SM). Statistical analyses of lithology, land-surface slope, land cover, and Koppen-Geiger climate classes are used to predict global subsidence susceptibility at a spatial resolution of 1 km2. The probability of groundwater depletion is estimated by identifying urban and irrigated areas suffering water stress and where groundwater demand is high. The analyses do not consider subsidence magnitude and rate, owing to the lack of this information at a global scale. Hence, the combination of subsidence susceptibility and the probability of groundwater depletion is used to predict a “proxy” of subsidence hazard, which permits identification of exposed areas where the probability of land subsidence occurrence is high or very high. Even though these results do not necessarily translate to direct impacts or damages, they are useful for identifying potential subsidence areas where further local-scale analysis is necessary. T he comparison of our model predictions with an independent validation dataset reveals a 94% capability to distinguish between subsidence and nonsubsidence areas, according to the value of the area under the receiver operating characteristic curve (see SM). The global exposure to potential subsidence is evaluated by calculating the number of inhabitants living in potential subsidence areas, i.e., subsidence hazard proxy, and the equivalent gross domestic product (GDP). T his “proxy” of exposed assets is calculated assuming that GDP per capita is homogeneous within each country. Finally, the evolution of potential global subsidence and the related exposure is predicted for 2040 for a global change scenario based on steady population growth and increasing greenhouse gas emissions (Shared Socioeconomic Pathways 2, Representative Concentration Pathway 8.5), which accounts for the greatest sea-level rise projections. ![Figure][5] Potential global subsidence The color scale indicates the probability intervals classified from very low (VL) to very high (VH), for every 30-arcsec resolution pixel (1 km by 1 km at the Equator). The white hatched polygons indicate countries where groundwater data is unavailable, and the potential subsidence only includes information on the susceptibility. See maps of other regions in supplementary materials. GRAPHIC: N. DESAI/ SCIENCE Our results suggest that potential subsidence threatens 12 million km2 (8%) of the global land surface with a probability greater than 50% (MH to VH in the figure). Potential subsidence areas are concentrated in and near densely urban and irrigated areas with high water stress and high groundwater demand, overlying some of the largest and most depleted aquifer systems ([ 5 ][6]) in Asia (e.g., North China Plain) and North America (e.g., Gulf of Mexico coastal plain); coastal and river delta areas worldwide (e.g., Vietnam, Egypt, or the Netherlands); and inland sedimentary basins of México, Iran, and the Mediterranean countries. Potential subsidence is lower in Africa, Australia, and South America, owing to the lower groundwater depletion ([ 6 ][7]). In central Africa, potential subsidence only includes information on the susceptibility, as groundwater depletion is unknown. In this region, subsidence susceptibility (see fig. S6) could be useful to prevent subsidence impacts on developing cities that during the next decades could rely more on the available groundwater resources. To evaluate the exposure to potential subsidence, we focus on areas where the potential subsidence probability is high or very high (see the figure). The cumulative potential subsidence area amounts to 2.2 million km2, or 1.6% of the land; includes 1.2 billion inhabitants, or 19% of the global population; and has an exposed GDP of US$ 8.19 trillion, or 12% of the global GDP. Hi gh-income countries account for 62% of the global exposed GDP but only 11% of the global exposed population, whereas low-income countries account for 54% of the global exposed population and 12% of the global exposed GDP. It is expected that the capability of low-income countries to implement the political, regulatory, and socioeconomic measures necessary to prevent and mitigate subsidence impact will be less than that for high-income countries. Potential subsidence threatens 484 million inhabitants living in flood-prone areas, 75% of whom live in fluvial areas and 25% of whom live near the coast. This number of threatened inhabitants corresponds to 50% of the global population exposed to flooding hazards according to previous estimates ([ 7 ][8]), demonstrating the importance of considering potential subsidence in global flooding risk analyses. Most of the global population exposed to potential subsidence live in Asia (86%), which is about 10 times the combined exposed population of North America and Europe (9%). The results indicate that 97% of the exposed global population is concentrated in 30 countries (see SM). India and China share the top two rankings of potential subsidence in terms of spatial extent and exposed population. Egypt and the Netherlands have the largest populations living in potential subsidence areas that are below the mean sea level. The greatest population densities in potential subsidence areas occur in Egypt and Indonesia, whereas the relative exposure per country, measured as the exposed population normalized by the total population, is greater than 30% for Egypt, Bangladesh, Netherlands, and Italy. The United States ranks first in terms of GDP exposed to potential subsidence, owing to its high GDP per capita. Combination of the aforementioned metrics permits derivation of a potential subsidence index ranking (see SM). Seven of the first ten ranked countries have the greatest subsidence impact, accounting for the greatest amount of reported damages (Netherlands, China, USA, Japan, Indonesia, México and Italy). During this century, climate change will cause serious impacts on the world's water resources through sea-level rise, more frequent and severe floods and droughts, changes in the mean value and mode of precipitation (rain versus snow), and increased evapotranspiration. Prolonged droughts will decrease groundwater recharge and increase groundwater depletion, intensifying subsidence. The global potential subsidence is predicted for 2040 using the same subsidence metrics and available global projections of water stress, water demand variations, climate, and population (see SM). Although predicted potential subsidence areas increase only by 7% globally, the threatened population is predicted to rise by 30%, affecting 1.6 billion inhabitants, 635 million of whom will be living in flood-prone areas. These changes will not be homogeneous. Between 2010 and 2040, the predicted population exposed to potential subsidence increases more than 80% in the Philippines, Iraq, Indonesia, México, Israel, Netherlands, Algeria, and Bangladesh. The increase will be moderate, less than 30%, for China, the United States, Italy, and Iran. Potential subsidence is forecasted to decrease in Japan and Germany, owing to effective groundwater management policies and population declines. Finally, potential subsidence is predicted to emerge in high-latitude northern countries like Canada and to increase in extent in Russia or Hungary, where climate change will favor longer dry seasons. Further advancements in the global evaluation of subsidence can be made when a global historical database on subsidence rate, magnitude, and extent has been compiled, which could be largely sourced from continental monitoring of surface displacements using satellite radar imagery ([ 8 ][9]). Widespread continuous monitoring of subsidence will permit better evaluation of the potential impact of land subsidence, especially in countries like Indonesia, México, and Iran, where local studies revealed the highest subsidence rates worldwide, but the national dimension of subsidence is still unknown. Further research also is necessary to evaluate the cost of damage caused by current and historical subsidence worldwide. The combination of damage information with hazard estimates will permit improved assessments of potential loss and design of cost-effective countermeasures. Presently, annual subsidence costs are only published for China (US$ 1.5 billion) and the Netherlands (US$ 4.8 billion) ([ 9 ][10]). The greater subsidence costs in the Netherlands owe to the exposed population below the mean sea level and the large investments made to prevent flooding. Our model, which does not yet consider mitigation measures, likely overestimates potential subsidence exposure in the Netherlands and Japan, where groundwater management has effectively controlled subsidence over the past decades ([ 10 ][11]). Our results identify 1596 major cities, or about 22% of the world's 7343 major cities that are in potential subsidence areas, with 57% of these cities also located in flood-prone areas. Moreover, subsidence threatens 15 of the 20 major coastal cities ranked with the highest flood risk worldwide ([ 11 ][12]), where potential subsidence can help delimit areas in which flooding risk could be increased and mitigation measures are necessary. Overall, potential global subsidence results can be useful to better define the spatial extent of poorly documented subsidence occurrences, discover unknown subsiding areas, prevent potential subsidence impacts wherever groundwater depletion occurs, and better identify areas where subsidence could increase the flooding risk. In any of these scenarios, an effective land-subsidence policy should include systematic monitoring and modeling of exposed areas, evaluation of potential damages, and cost-benefit analyses permitting implementation of adequate mitigation or adaptation measures. These measures should consider groundwater regulation and strategic long-term measures, such as the development of alternative water supplies and the protection and (or) enhancement of natural or artificial recharge of aquifers. Considering that the potential subsidence may affect 635 million inhabitants living in flood-prone areas in 2040, it is of prime importance that potential subsidence is quantified and systematically included in flood risk analyses and related mitigation strategies. [science.sciencemag.org/content/371/6524/34/suppl/DC1][13] 1. [↵][14]1. D. L. Galloway, 2. T. J. Burbey , Hydrogeol. J. 19, 1459 (2011). [OpenUrl][15] 2. [↵][16]1. J. S. Famiglietti , Nat. Clim. Chang. 4, 945 (2014). [OpenUrl][17] 3. [↵][18]1. K. E. Trenberth , Clim. Res. 47, 123 (2011). [OpenUrl][19][CrossRef][20][Web of Science][21] 4. [↵][22]1. J. P. M. Syvitski et al ., Nat. Geosci. 2, 681 (2009). [OpenUrl][23][CrossRef][24][Web of Science][25] 5. [↵][26]1. P. Döll, 2. H. Müller Schmied, 3. C. 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Ingebritsen (U.S. Geological Survey) helped to improve the manuscript. Funding for this study was provided partly by the Spanish Research Agency (AQUARISK, PRX19/00065, TEC2017-85244-C2-1-P projects) and PRIMA RESERVOIR project, and by all the institutions represented in the Land Subsidence International Initiative from UNESCO. G.H.-G., P.E., R.T., M.B.-P, and J.L.-V. designed the study, performed the analysis, and wrote the initial manuscript with input from all other authors. R.M.M., E.C.-C., and M.R. advised on the susceptibility analysis. R.M.M., J.L., P.T., and G.E. advised on hazard analysis. D.C.-F., J.L., P.T., E.C.C., G.E., D.G., W.C.H., N.K., M.S., L.T., H.W., and S.Y. advised on global exposure analysis. R.T., M.B.P., R.M.M., J.L., P.T., W.-C.H., N.K., L.T., H.W., and S.Y. contributed essential data for the analysis. All the authors edited and revised the manuscript through the different reviews. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. The authors declare no competing interests. All data included in this study are available at figshare ([ 12 ][45]). 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SCI COMMUN ### Areas to watch As biomedical scientists continue to battle the deadly pandemic this year to help the world return to normalcy, researchers across the disciplines still aim to hit big milestones or launch new projects despite the challenges brought by COVID-19. European scientists will also have to contend with the aftermath of Brexit. Many U.S. scientists, in contrast, have a more hopeful political outlook, with some likely to play an invigorated role in tackling another global crisis, climate change, after President-elect Joe Biden, who has vowed to make it a top priority, is sworn in this month. In this section, Science 's news staff forecasts areas of research and policy we expect to make headlines this year, from protecting the high seas' biodiversity to probing how ancient humans interacted. ### Global warming Nearly 8 years have passed since the fifth assessment report from the United Nations's Intergovernmental Panel on Climate Change, the famed body of volunteer climate scientists that since 1990 has chronicled humanity's persistent warming of the planet. The sixth installment, crafted by more than 700 scientists and delayed by the pandemic, will come out in sections this year and next, and it's expected to further sharpen the picture of the human impact on climate. Its findings will be bolstered by a new generation of climate models and scenarios, fed by indicators of unabated global change: data showing accelerating sea level rise; rapid ice melt at the poles; and waves of extreme heat, drought, and fire. In November, the world's countries will meet in Scotland's Glasgow for the next U.N. climate summit, where they are expected to increase the ambitions of their pledged cuts in greenhouse gases and agree on a full set of rules to implement the Paris agreement. Among the attendees will be the United States, which President-elect Joe Biden has said will rejoin the pact. ### Public health The launch of immunization campaigns in many countries has raised hopes that the COVID-19 pandemic can be brought to an end. But how exactly it started remains murky, and a World Health Organization international team of 10 scientists will travel to China several times this year as part of an investigation into the pandemic coronavirus' origins—a politically sensitive mission because the United States and China have sparred over who is to blame for the pandemic. The team hopes to discover the virus' closest relatives in bats, where and how it jumped to humans, whether another species acted as an intermediate host, and, most important, how we can prevent other pandemic viruses from emerging. ### National security Restoring U.S.-Chinese scientific collaborations to health could be a test of President-elect Joe Biden's success in negotiating with the Asian superpower on trade, immigration, and security concerns. A new U.S. government–sponsored forum on science, technology, and national security will advise the new administration on how to strike the right balance between openness and preventing the theft of new technology. A new U.S. law provides stiff penalties for federal grant applicants who fail to disclose all sources of funding when submitting a proposal, based on the assumption that greater transparency is the best way to monitor ties with China and other entities posing potential threats to U.S. security. University leaders are hoping Biden will reverse President Donald Trump's restrictive immigration policies and avoid ratcheting up economic and political tensions. But prominent Republicans in Congress are threatening even more punitive steps against China. ### Infectious diseases To complement mass vaccinations against COVID-19, drug companies this year will dash to custom design drugs that block the pandemic coronavirus and treat the disease's symptoms. Even if many people receive one of the new, highly effective vaccines approved in recent weeks by regulators, the virus is expected to remain endemic. In 2020, only the antiviral remdesivir and a handful of other drugs, all originally designed to treat other conditions, showed even limited benefits against the disease. To identify new drug candidates, researchers have deployed artificial intelligence and supercomputers, and more than 590 experimental drugs are in development, according to a leading pharmaceutical industry tracker. For example, researchers have high hopes for compounds that disrupt reproduction of the pandemic virus by inhibiting one of its two proteases. Cocktails of such therapies could tame the virus, an approach used successfully against HIV. The protease inhibitors and other compounds look promising in cell and animal studies. But studies on human volunteers are only getting started, and it could take years to pass safety and efficacy reviews. ### Planetary science Mars's thin air makes it hard to slow a probe to a soft landing. Of the 18 robotic probes sent to the planet's surface in the past 50 years, eight have crashed. This year, two more will attempt a touchdown. On 18 February, NASA's SUV-size rover, Perseverance, will take the plunge, slowed by parachutes and retrorockets on a “sky crane” platform. After landing in Jezero crater, near a fossilized river delta, the rover will collect rock samples for eventual return to Earth. Around the same time, China's Tianwen-1 mission will arrive with an orbiter, a lander platform, and a rover the size of a golf cart. Officials have chosen a landing site not far from Jezero, along the southern edge of Utopia Planitia, a broad plain that may have been repaved by ancient flows of mud. A successful touchdown would be China's first on Mars. ### Microscopy Researchers aim this year to sharpen the resolution of cryo–electron microscopy (cryo-EM), a technique for studying protein structure that may yield new insights into their roles in maintaining human health and causing disease. Another technique, x-ray crystallography, has long been the gold standard for mapping individual atoms within a 3D protein structure. But it only works for proteins that can be packed into crystals. Cryo-EM doesn't require crystals, and its resolution has steadily improved over the past decade. In 2020, it crossed the threshold of atomic resolution as researchers using cryo-EM microscopes equipped with improved electron detectors and software mapped the structure of apoferritin, an iron-binding protein. That protein is unusually rigid, which made it easier to hold steady during cryo-EM mapping. Next, researchers want to image less rigid proteins. Success would be a boon to structural biologists, allowing them to generate highly detailed maps of large proteins and complexes of multiple proteins that cannot be crystallized. ### Astronomy The long wait will soon be over: NASA's much-delayed flagship observatory, the James Webb Space Telescope (JWST), is set to finally take to the skies on 31 October. JWST is the successor to the Hubble Space Telescope, with a 6.5-meter-wide mirror that has six times its predecessor's light-gathering power. The gold-coated, honeycombed mirror will be cooled so it can collect the infrared light of distant objects, red-shifted by the universe's expansion. JWST will be sensitive enough to scrutinize the atmospheres of nearby exoplanets for signs of life and gather the light of the universe's first stars and galaxies. The $8.8 billion spacecraft, which will cost billions more and launch years later than originally planned, recently endured final tests—violent shaking to simulate launch. This month, engineers are unfolding its mirror and unfurling its multilayered Sun shield one last time to check that all is well. By midyear, JWST will be packed up and shipped to French Guiana, where it will be loaded onto a European Ariane 5 rocket. Next stop: deep space. ### Energy The Joint European Torus (JET), the world's largest fusion reactor, will this year embark on a campaign to generate substantial amounts of fusion power. The U.K.-based JET is a tokamak, which uses powerful magnets to constrain a hot plasma so that atomic nuclei crash together and fuse, releasing energy. After an upgrade, JET has a new metallic lining and extra heating power; in this year's trials, it will be fed a potent mix of the hydrogen isotopes deuterium and tritium (D-T)—a fuel rarely used because radioactive tritium needs careful handling and cleanup. In 1997, the last time this fuel mix was used, JET generated 16 megawatts of power for a few seconds, well short of the power consumed to make it happen. The new campaign will initially aim for similar power levels but try to sustain them for longer. That will help in planning for the huge ITER reactor, under construction in France, which has a similar shape and lining. ITER is due to start operations in 2025, but will not begin to use D-T fuel until the mid 2030s. ### Nutrition Help may arrive this year for millions of malnourished children who remain sickly and fail to fully recover even after receiving proper nutrition and treatments for being underfed. Pandemic-related disruptions and job losses are expected to cause the number of such children to skyrocket. One problem for underfed children is disruption of the gut microbiome, which leads to an immature, inefficient digestive system that stunts growth. To repair the microbiomes, health specialists are looking forward to results of a study in Bangladesh that evaluated a low-cost nutritional supplement; it's a mix of easy-to-find ingredients, such as chickpeas, bananas, and soy and peanut flours. In 2019, this team reported that in experiments in mice and pigs, followed by a monthlong pilot study of 60 children, the supplement led to gut repair, as indicated by changes in blood markers. The study did not last long enough to test effects on growth. Since then, these researchers have been comparing the intervention with an existing supplement in a larger, 3-month trial of malnourished children. ### Conservation Few rules protect biodiversity in the two-thirds of the ocean that lies outside nations' sovereign waters. This year, the United Nations is expected to finalize the first treaty specifically intended to change that. The pact is expected to provide a way to designate marine protected areas (MPAs) on the high seas; researchers have been developing a list of candidates and supporting evidence. The draft language also sets minimum standards for environmental impact assessments that nations would be required to conduct before starting commercial activities that might harm marine life. A new, international scientific and technical body, similar to one that manages marine life around Antarctica, would review MPA proposals. The treaty draft also provides for a system to manage genetic sequences taken from marine organisms living in the high seas. ### Archaeology Expect to see studies of ancient humans follow new paths this year, as researchers combine analyses of ancient DNA with other molecular and microbial clues to examine social ties and migrations. Scientists will merge DNA evidence with data from proteins and isotopes, as well as microfossils and pathogens from bones, tooth plaque, and fossilized poop. Such studies this year could help determine which early Celtic family members inherited wealth. They could help identify the homeland of the biblical Philistines and clarify the identities of early Anglo-Saxons and Greeks in Europe, as well as mummies in China and Egypt. ### Public health An obscure $4 billion U.S. government fund that compensates people injured by vaccines is poised to become more tight-fisted this month. Changes proposed by the Trump administration will likely take effect in mid-January, making it more complicated and time consuming for people to win a payout if they sustain shoulder injuries after incorrectly administered injections with flu, tetanus, and other vaccines. The new rules won't affect people who might be injured by COVID-19 vaccines, who would need to apply to a different government program for compensation. But claims that other vaccines caused shoulder injuries have grown on the heels of expanded influenza vaccination and a 2010 paper in which government scientists first described “shoulder injury related to vaccine administration.” ### Biomedicine For more than 3 decades, scientists have dreamed of shrinking tumors by shutting off a protein called KRAS whose growth signals drive many cancer types. KRAS was thought to be impervious to drugs, in part because it offered no obvious pockets that inhibitors could target. But multiple companies have now developed compounds that fit into a groove on some cancer-promoting mutant KRAS proteins and curb their signals. The drugs have shown promising results, first in rodents and then in cancer patients. In December 2020, Amgen asked the Food and Drug Administration to review its KRAS drug, sotorasib, setting the stage for approval this year of the first member of this novel drug class. The drug could first be licensed for use in certain lung cancer patients. Another firm is expected to submit its KRAS drug for approval this year as well.

Two American B-52 bombers flew another show-of-force mission in the Persian Gulf on Wednesday, a week after President Trump warned Iran that he would hold it accountable "if one American is killed" in rocket attacks in Iraq that the administration and military officials blamed on Tehran. The warplanes' 36-hour round-trip mission from Minot Air Force Base in North Dakota was the third time in six weeks that Air Force bombers had conducted long-range flights about 60 miles off the Iranian coast, moves that military officials said were intended to deter Iran from attacking American troops in the region. The United States periodically conducts such quick demonstration missions to the Middle East and Asia to showcase American air power to allies and adversaries. But tensions have been rising in advance of the Jan. 3 anniversary of the American drone strike that killed Maj. Gen. Qassim Suleimani, the commander of Iran's elite Quds Force of the Islamic Revolutionary Guards Corps, and the Iraqi leader of an Iranian-backed militia -- deaths that Iranian leaders repeatedly insist they have not yet avenged.

We review the EfficientQA competition from NeurIPS 2020. The competition focused on open-domain question answering (QA), where systems take natural language questions as input and return natural language answers. The aim of the competition was to build systems that can predict correct answers while also satisfying strict on-disk memory budgets. These memory budgets were designed to encourage contestants to explore the trade-off between storing large, redundant, retrieval corpora or the parameters of large learned models. In this report, we describe the motivation and organization of the competition, review the best submissions, and analyze system predictions to inform a discussion of evaluation for open-domain QA.

We study the problem of testing the covariance matrix of a high-dimensional Gaussian in a robust setting, where the input distribution has been corrupted in Huber's contamination model. Specifically, we are given i.i.d. samples from a distribution of the form $Z = (1-\epsilon) X + \epsilon B$, where $X$ is a zero-mean and unknown covariance Gaussian $\mathcal{N}(0, \Sigma)$, $B$ is a fixed but unknown noise distribution, and $\epsilon>0$ is an arbitrarily small constant representing the proportion of contamination. We want to distinguish between the cases that $\Sigma$ is the identity matrix versus $\gamma$-far from the identity in Frobenius norm. In the absence of contamination, prior work gave a simple tester for this hypothesis testing task that uses $O(d)$ samples. Moreover, this sample upper bound was shown to be best possible, within constant factors. Our main result is that the sample complexity of covariance testing dramatically increases in the contaminated setting. In particular, we prove a sample complexity lower bound of $\Omega(d^2)$ for $\epsilon$ an arbitrarily small constant and $\gamma = 1/2$. This lower bound is best possible, as $O(d^2)$ samples suffice to even robustly {\em learn} the covariance. The conceptual implication of our result is that, for the natural setting we consider, robust hypothesis testing is at least as hard as robust estimation.

January is just a couple of days away, and there'll soon be a fresh slate of games you can pick up at no extra cost if you're a PlayStation Plus subscriber. Among the January selections is Shadow of the Tomb Raider, the third entry in the rebooted Tomb Raider series. This time around, Lara Croft uses her stealth skills and other field expertise to "save the world from a Maya apocalypse." In most regions, the lineup includes the PS4 version of Greedfall, an RPG with magic and monsters set in the 17th century. A PS5 edition (along with an Xbox Series S/X one) is in the works, but it's unclear if you'll be able to upgrade for free.

This story originally appeared on WIRED UK. This is not a year we'll look back on fondly. It began with Australia on fire and ends with more than 1.5 million dead in a pandemic. But there have been bright points in this annus horribilis. While many of us saved lives by hunkering down at home watching Netflix, a communal act of selflessness that shouldn't be soon forgotten, progress was made in science, the environment, and even politics--Biden won!

GloVe learns word embeddings by leveraging statistical information from word co-occurrence matrices. However, word pairs in the matrices are extracted from a predefined local context window, which might lead to limited word pairs and potentially semantic irrelevant word pairs. In this paper, we propose SemGloVe, which distills semantic co-occurrences from BERT into static GloVe word embeddings. Particularly, we propose two models to extract co-occurrence statistics based on either the masked language model or the multi-head attention weights of BERT. Our methods can extract word pairs without limiting by the local window assumption and can define the co-occurrence weights by directly considering the semantic distance between word pairs. Experiments on several word similarity datasets and four external tasks show that SemGloVe can outperform GloVe.