As part of the Greenland Ice Mapping Project (GIMP) we have produced three geospatial data sets for the entire ice sheet and periphery. These are (1) a complete, 15 m resolution image mosaic, (2) ...ice-covered and ice-free terrain classification masks, also posted to 15 m resolution, and (3) a complete, altimeter-registered digital elevation model posted at 30 m. The image mosaic was created from a combination of Landsat-7 and RADARSAT-1 imagery acquired between 1999 and 2002. Each pixel in the image is stamped with the acquisition date and geo-registration error to facilitate change detection. This mosaic was then used to manually produce complete ice-covered and ice-free land classification masks. Finally, we used satellite altimetry and stereo-photogrammetric digital elevation models (DEMs) to enhance an existing DEM for Greenland, substantially improving resolution and accuracy over the ice margin and periphery.
Current multiplexed diagnostics for Zika, dengue, and chikungunya viruses are situated outside the intersection of affordability, high performance, and suitability for use at the point-of-care in ...resource-limited settings. Consequently, insufficient diagnostic capabilities are a key limitation facing current Zika outbreak management strategies. Here we demonstrate highly sensitive and specific detection of Zika, chikungunya, and dengue viruses by coupling reverse-transcription loop-mediated isothermal amplification (RT-LAMP) with our recently developed quenching of unincorporated amplification signal reporters (QUASR) technique. We conduct reactions in a simple, inexpensive and portable "LAMP box" supplemented with a consumer class smartphone. The entire assembly can be powered by a 5 V USB source such as a USB power bank or solar panel. Our smartphone employs a novel algorithm utilizing chromaticity to analyze fluorescence signals, which improves the discrimination of positive/negative signals by 5-fold when compared to detection with traditional RGB intensity sensors or the naked eye. The ability to detect ZIKV directly from crude human sample matrices (blood, urine, and saliva) demonstrates our device's utility for widespread clinical deployment. Together, these advances enable our system to host the key components necessary to expand the use of nucleic acid amplification-based detection assays towards point-of-care settings where they are needed most.
Double-stranded DNA (dsDNA) binding and cleavage by Cas9 is a hallmark of type II CRISPR-Cas bacterial adaptive immunity. All known Cas9 enzymes are thought to recognize DNA exclusively as a natural ...substrate, providing protection against DNA phage and plasmids. Here, we show that Cas9 enzymes from both subtypes II-A and II-C can recognize and cleave single-stranded RNA (ssRNA) by an RNA-guided mechanism that is independent of a protospacer-adjacent motif (PAM) sequence in the target RNA. RNA-guided RNA cleavage is programmable and site-specific, and we find that this activity can be exploited to reduce infection by single-stranded RNA phage in vivo. We also demonstrate that Cas9 can direct PAM-independent repression of gene expression in bacteria. These results indicate that a subset of Cas9 enzymes have the ability to act on both DNA and RNA target sequences, and suggest the potential for use in programmable RNA targeting applications.
The degree of aggregation and/or coalescence of Au-citrate nanoparticles (AuNPs, mean size 21.5 ± 2.9 nm), after delivery in simulated seawater, are shown to be concentration-dependent. At low ...concentrations no coalescence and only limited aggregation of primary particles were found. Experiments were performed in which the marine bivalve (Ruditapes philippinarum) was exposed to AuNPs or dissolved Au and subsequently, bivalve tissues were studied by Scanning and Transmission Electron Microscopy and chemical analyses. We show that the bivalve accumulates gold in both cases within either the digestive gland or gill tissues, in different concentrations (including values of predicted environmental relevance). After 28 days of exposure, electron-dense deposits (corresponding to AuNPs, as proven by X-ray microanalysis) were observed in the heterolysosomes of the digestive gland cells. Although non-measurable solubility of AuNPs in seawater was found, evidence is presented of the toxicity produced by Au3+ dissolved species (chloroauric acid solutions) and its relevance is discussed.
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► Limited aggregation for Au-citrate NPs at low concentrations in sea water media. ► Au-citrate NPs are not soluble in seawater after 48 h exposure. ► Gold accumulation is found under exposure of bivalve to AuNPs or chloroauric acid. ► Location of AuNPs at heterolysosomes of digestive gland cells of Ruditapes philippinarum. ► High toxicity of Au3+ dissolved species (chlororauric acid solutions).
Concentration-dependent physico-chemical evolution of citrate-stabilized AuNPs in sea water media, and their uptake and sub-cellular location in Ruditapes philippinarum.
• Geminiviruses are plant viruses with circular, single‐stranded (ss) DNA genomes that infect a wide range of species and cause important losses in agriculture. Geminiviruses do not encode their own ...DNA polymerase, and rely on the host cell machinery for their replication. • Here, we identify a positive effect of the curtovirus Beet curly top virus (BCTV) on the begomovirus Tomato yellow leaf curl Sardinia virus (TYLCSV) infection in Nicotiana benthamiana plants. • Our results show that this positive effect is caused by the promotion of TYLCSV replication by BCTV C2. Transcriptomic analyses of plants expressing C2 unveil an up‐regulation of cell cycle‐related genes induced on cell cycle re‐entry; experiments with two mutated versions of C2 indicate that this function resides in the N‐terminal part of C2, which is also sufficient to enhance geminiviral replication. Moreover, C2 expression promotes the replication of other geminiviral species, but not of RNA viruses. • We conclude that BCTV C2 has a novel function in the promotion of viral replication, probably by restoring the DNA replication competency of the infected cells and thus creating a favourable cell environment for viral spread. Because C2 seems to have a broad impact on the replication of geminiviruses, this mechanism might have important epidemiological implications.
The next era of assessment in medical education promises new assessment systems, increased focus on ensuring high-quality equitable patient care, and precision education to drive learning and ...improvement. The potential benefits of using learning analytics and technology to augment medical training abound. To ensure that the ideals of this future for medical education are realized, educators should partner with trainees to build and implement new assessment systems. Coproduction of assessment systems by educators and trainees will help to ensure that new educational interventions are feasible and sustainable. In this paper, the authors provide a trainee perspective on 5 key areas that affect trainees in the next era of assessment: (1) precision education, (2) assessor education, (3) transparency in assessment development and implementation, (4) ongoing evaluation of the consequences of assessment, and (5) patient care data as sources of education outcomes.As precision education is developed, it is critical that trainees understand how their educational data are collected, stored, and ultimately utilized for educational outcomes. Since assessors play a key role in generating assessment data, it is important that they are prepared to give high-quality assessments and are continuously evaluated on their abilities. Transparency in the development and implementation of assessments requires communicating how assessments are created, the evidence behind them, and their intended uses. Furthermore, ongoing evaluation of the intended and unintended consequences that new assessments have on trainees should be conducted and communicated to trainees. Finally, trainees should participate in determining what patient care data are used to inform educational outcomes. The authors believe that trainee coproduction is critical to building stronger assessment systems that utilize evidence-based educational theories for improved learning and ultimately better patient care.
Exploring the perceptions of underrepresented in medicine (URiM) students about the medical education curriculum and learning environment could optimize their education outcomes. The current study ...delineated perceptions of URiM medical students about the unique elements and characteristics of an impactful medical education program that create a positive, supportive learning environment culture.
We conducted in-depth interviews with 15 URiM students between January 2018 and April 2018. Interviewees were recruited from an accredited medical education program in Historically Black Colleges and Universities (HBCUs). The University is also a member of the Hispanic Association of Colleges and Universities in the U.S. The main question that guided the study was, "What do URiM students at a Historically Black Colleges and Universities (HBCU) medical school believe would make a medical education program (MEP) impactful?" We used the grounded theory analytical approach and performed content analysis via qualitative thematic evaluation.
Of 112 enrolled medical students (MS), 15 verbally consented to participation. We identified four general themes and several subthemes. The themes include 1) Grounding learning in the community; 2) Progressive system-based practice competency; 3) Social justice competency and 4) Trauma-informed medical education delivery. Theme 1 included the following subthemes (a) community engagement, and (b) student-run clinic, mobile clinic, and homeless clinic rotations. Theme 2 includes (a) interprofessional learning and (b) multidisciplinary medicine for cultivating a 'just' healthcare system. Theme 3 includes (a) longitudinal social justice curriculum, (b) advocacy, and (c) health disparity research. Theme 4 had the following subdomains (a) early and ongoing mentoring and (b) provision of supportive policies, services and practices to maximize learning and mental health.
Our learners found that social justice, trauma-informed, community-based curricula are impactful for URiM learners. These findings highlight the need for further research to assess the impact of permeating the championship culture, community cultural wealth, and transformational education in all aspects of the MEP in providing a supporting and positive learning environment for URiM students.
Context. The most highly accreting quasars are of special interest in studies of the physics of active galactic nuclei (AGNs) and host galaxy evolution. Quasars accreting at high rates (L/LEdd ∼ 1) ...hold promise for use as “standard candles”: distance indicators detectable at very high redshift. However, their observational properties are still largely unknown. Aims. We seek to identify a significant number of extreme accretors. A large sample can clarify the main properties of quasars radiating near L/LEdd ∼ 1 (in this paper they are designated as extreme Population A quasars or simply as extreme accretors) in the Hβ spectral range for redshift ≲0.8. Methods. We use selection criteria derived from four-dimensional Eigenvector 1 (4DE1) studies to identify and analyze spectra for a sample of 334 candidate sources identified from the SDSS DR7 database. The source spectra were chosen to show a ratio RFeII between the FeII emission blend at λ4570 and Hβ, RFeII > 1. Composite spectra were analyzed for systematic trends as a function of Fe II strength, line width, and OIII strength. We introduced tighter constraints on the signal-to-noise ratio (S/N) and RFeII values that allowed us to isolate sources most likely to be extreme accretors. Results. We provide a database of detailed measurements. Analysis of the data allows us to confirm that Hβ shows a Lorentzian function with a full width at half maximum (FWHM) of Hβ ≤ 4000 km s−1. We find no evidence for a discontinuity at 2000 km s−1 in the 4DE1, which could mean that the sources below this FWHM value do not belong to a different AGN class. Systematic OIII blue shifts, as well as a blueshifted component in Hβ are revealed. We interpret the blueshifts as related to the signature of outflowing gas from the quasar central engine. The FWHM of Hβ is still affected by the blueshifted emission; however, the effect is non-negligible if the FWHM Hβ is used as a “virial broadening estimator” (VBE). We emphasize a strong effect of the viewing angle on Hβ broadening, deriving a correction for those sources that shows major disagreement between virial and concordance cosmology luminosity values. Conclusions. The relatively large scatter between concordance cosmology and virial luminosity estimates can be reduced (by an order of magnitude) if a correction for orientation effects is included in the FWHM Hβ value; outflow and sample definition yield relatively minor effects.
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