Soil property and class maps for the continent of Africa were so far only available at very generalised scales, with many countries not mapped at all. Thanks to an increasing quantity and ...availability of soil samples collected at field point locations by various government and/or NGO funded projects, it is now possible to produce detailed pan-African maps of soil nutrients, including micro-nutrients at fine spatial resolutions. In this paper we describe production of a 30 m resolution Soil Information System of the African continent using, to date, the most comprehensive compilation of soil samples (Formula: see text) and Earth Observation data. We produced predictions for soil pH, organic carbon (C) and total nitrogen (N), total carbon, effective Cation Exchange Capacity (eCEC), extractable-phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), iron (Fe), zinc (Zn)-silt, clay and sand, stone content, bulk density and depth to bedrock, at three depths (0, 20 and 50 cm) and using 2-scale 3D Ensemble Machine Learning framework implemented in the mlr (Machine Learning in R) package. As covariate layers we used 250 m resolution (MODIS, PROBA-V and SM2RAIN products), and 30 m resolution (Sentinel-2, Landsat and DTM derivatives) images. Our fivefold spatial Cross-Validation results showed varying accuracy levels ranging from the best performing soil pH (CCC = 0.900) to more poorly predictable extractable phosphorus (CCC = 0.654) and sulphur (CCC = 0.708) and depth to bedrock. Sentinel-2 bands SWIR (B11, B12), NIR (B09, B8A), Landsat SWIR bands, and vertical depth derived from 30 m resolution DTM, were the overall most important 30 m resolution covariates. Climatic data images-SM2RAIN, bioclimatic variables and MODIS Land Surface Temperature-however, remained as the overall most important variables for predicting soil chemical variables at continental scale. This publicly available 30-m Soil Information System of Africa aims at supporting numerous applications, including soil and fertilizer policies and investments, agronomic advice to close yield gaps, environmental programs, or targeting of nutrition interventions.
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the most formidable challenge to humanity in a century. It is widely ...believed that prepandemic normalcy will never return until a safe and effective vaccine strategy becomes available and a global vaccination programme is implemented successfully. Here, we discuss the immunological principles that need to be taken into consideration in the development of COVID-19 vaccine strategies. On the basis of these principles, we examine the current COVID-19 vaccine candidates, their strengths and potential shortfalls, and make inferences about their chances of success. Finally, we discuss the scientific and practical challenges that will be faced in the process of developing a successful vaccine and the ways in which COVID-19 vaccine strategies may evolve over the next few years.
Today's college students are at increased risk for depression. Therefore, accurate and sustainable assessment of depressive symptoms among college students has become an important issue. One ...promising instrument for depression screening in college settings is the Patient Health Questionnaire-9 (PHQ-9), a 9-item self-report measure developed in primary care and designed to assess the presence of Diagnostic and Statistical Manual of Mental Disorders (4th ed.) symptom criteria for major depressive disorder. Although the PHQ-9 has been well validated in primary care settings, no studies have examined its factor structure for diverse college populations in the United States. This study used confirmatory factor analysis to test competing measurement models and the measurement invariance of the PHQ-9 across gender (men and women) and racial/ethnic groups (African American, Asian American, European American, Latino/a American) in a sample of 857 U.S. college students. Results supported a 1-factor model of the PHQ-9. Based on configural, metric, and scalar invariance test results, the PHQ-9 assesses depressive symptoms equivalently across gender and racial/ethnic groups. In support of validity evidence, PHQ-9 scores were positively associated with alcohol use and negatively associated with mental well-being. Implications for future research and assessment are discussed.
Public Significance Statement
The current study found that the PHQ-9 assesses depressive symptoms equivalently across diverse gender and racial/ethnic college student populations. The results support the promising utility of PHQ-9 as a brief depression assessment in college settings.
Alzheimer's disease is the primary cause of dementia worldwide, with an increasing morbidity burden that may outstrip diagnosis and management capacity as the population ages. Current methods ...integrate patient history, neuropsychological testing and MRI to identify likely cases, yet effective practices remain variably applied and lacking in sensitivity and specificity. Here we report an interpretable deep learning strategy that delineates unique Alzheimer's disease signatures from multimodal inputs of MRI, age, gender, and Mini-Mental State Examination score. Our framework linked a fully convolutional network, which constructs high resolution maps of disease probability from local brain structure to a multilayer perceptron and generates precise, intuitive visualization of individual Alzheimer's disease risk en route to accurate diagnosis. The model was trained using clinically diagnosed Alzheimer's disease and cognitively normal subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset (n = 417) and validated on three independent cohorts: the Australian Imaging, Biomarker and Lifestyle Flagship Study of Ageing (AIBL) (n = 382), the Framingham Heart Study (n = 102), and the National Alzheimer's Coordinating Center (NACC) (n = 582). Performance of the model that used the multimodal inputs was consistent across datasets, with mean area under curve values of 0.996, 0.974, 0.876 and 0.954 for the ADNI study, AIBL, Framingham Heart Study and NACC datasets, respectively. Moreover, our approach exceeded the diagnostic performance of a multi-institutional team of practicing neurologists (n = 11), and high-risk cerebral regions predicted by the model closely tracked post-mortem histopathological findings. This framework provides a clinically adaptable strategy for using routinely available imaging techniques such as MRI to generate nuanced neuroimaging signatures for Alzheimer's disease diagnosis, as well as a generalizable approach for linking deep learning to pathophysiological processes in human disease.
The Milky Way hosts a hot, diffuse, gaseous halo based on detections of z = 0 Ov II and Ov III absorption lines in quasar spectra and emission lines in blank-sky spectra. Here we improve constraints ...on the structure of the hot gas halo by fitting a radial model to a much larger sample of Ov II and Ov III emission line measurements from XMM-Newton/EPIC-MOS spectra compared to previous studies. We assume a modified beta -model for the halo density distribution and a constant-density Local Bubble from which we calculate emission to compare with the observations. The combination of absorption and emission line analysis implies a sub-solar gas metallicity that decreases with radius, but that also must be 0.3 Z to be consistent with the pulsar dispersion measure toward the Large Magellanic Cloud.
Reducing the availability of highly lethal and commonly used suicide methods has been associated with declines in suicide rates of as much as 30%-50% in other countries. The theory and evidence ...underlying means restriction is outlined. Most evidence of its efficacy comes from population-level interventions and natural experiments. In the U.S., where 51% of suicides are completed with firearms and household firearm ownership is common and likely to remain so, reducing a suicidal person's access to firearms will usually be accomplished not by fiat or other legislative initiative but rather by appealing to individual decision, for example, by counseling at-risk people and their families to temporarily store household firearms away from home or otherwise making household firearms inaccessible to the at-risk person until they have recovered. Providers, gatekeepers, and gun owner groups are important partners in this work. Research is needed in a number of areas: communications research to identify effective messages and messengers for "lethal means counseling," clinical trials to identify effective interventions, translational research to ensure broad uptake of these interventions across clinical and community settings, and foundational research to better understand method choice and substitution. Approaches to suicide methods other than firearms are discussed. Means restriction is one of the few empirically based strategies to substantially reduce the number of suicide deaths.
THE STRUCTURE OF THE MILKY WAY'S HOT GAS HALO Miller, Matthew J; Bregman, Joel N
Astrophysical journal/The Astrophysical journal,
06/2013, Letnik:
770, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Milky Way's million degree gaseous halo contains a considerable amount of mass that, depending on its structural properties, can be a significant mass component. In order to analyze the structure ...of the Galactic halo, we use XMM-Newton Reflection Grating Spectrometer archival data and measure Ovii Kalpha absorption-line strengths toward 26 active galactic nuclei, LMC X-3, and two Galactic sources (4U 1820-30 and X1735-444). Although the metallicity of the halo gas is a large uncertainty in our analysis, we place a lower limit on the halo gas between the Sun and the Large Magellanic Cloud (LMC). We find that Z > or ~ 0.2 Z based on the pulsar dispersion measure toward the LMC.
ABSTRACT The Fermi bubbles are two lobes filled with non-thermal particles that emit gamma rays, extend vertically from the Galactic center, and formed from either nuclear star formation or accretion ...activity on Sgr A*. Simulations predict a range of shock strengths as the bubbles expand into the surrounding hot gas halo ( K), but with significant uncertainties in the energetics, age, and thermal gas structure. The bubbles should contain thermal gas with temperatures between 106 and 108 K, with potential X-ray signatures. In this work, we constrain the bubbles' thermal gas structure by modeling O vii and O viii emission line strengths from archival XMM-Newton and Suzaku data. Our emission model includes a hot thermal volume-filled bubble component cospatial with the gamma-ray region, and a shell of compressed material. We find that a bubble/shell model with cm−3 and with log(T) 6.60-6.70 is consistent with the observed line intensities. In the framework of a continuous Galactic outflow, we infer a bubble expansion rate, age, and energy injection rate of km s−1, Myr, and erg s−1. These estimates are consistent with the bubbles forming from a Sgr A* accretion event rather than from nuclear star formation.
The Extended Distribution of Baryons around Galaxies Bregman, Joel N.; Anderson, Michael E.; Miller, Matthew J. ...
Astrophysical journal/The Astrophysical journal,
07/2018, Letnik:
862, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We summarize and reanalyze observations bearing on missing galactic baryons, where we propose a consistent picture for halo gas in L L* galaxies. The hot X-ray-emitting halos are detected to 50-70 ...kpc, where typically Mhot(<50 kpc) ∼ 5 × 109 M , and with density n ∝ r−3/2. When extrapolated to R200, the gas mass is comparable to the stellar mass, but about half of the baryons are still missing from the hot phase. If extrapolated to 1.7R200-3R200, the ratio of baryon to dark matter approaches the cosmic value. Significantly flatter density profiles are unlikely for R < 50 kpc, and they are disfavored but not ruled out for R > 50 kpc. For the Milky Way, the hot halo metallicity lies in the range 0.3-1 solar for R < 50 kpc. Planck measurements of the thermal Sunyaev-Zel'dovich (SZ) effect toward stacked luminous galaxies (primarily early type) indicate that most of their baryons are hot, are near the virial temperature, and extend beyond R200. This stacked SZ signal is nearly an order of magnitude larger than that inferred from the X-ray observations of individual (mostly spiral) galaxies with M* > 1011.3 M . This difference suggests that the hot halo properties are distinct for early- and late-type galaxies, possibly due to different evolutionary histories. For the cooler gas detected in UV absorption line studies, we argue that there are two absorption populations: extended halos, and disks extending to ∼50 kpc, containing most of this gas, and with masses a few times lower than the stellar masses. Such extended disks are also seen in 21 cm H i observations and in simulations.
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