The accuracy of machine learning tasks critically depends on high quality ground truth data. Therefore, in many cases, producing good ground truth data typically involves trained professionals; ...however, this can be costly in time, effort, and money. Here we explore the use of crowdsourcing to generate a large number of training data of good quality. We explore an image analysis task involving the segmentation of corn tassels from images taken in a field setting. We investigate the accuracy, speed and other quality metrics when this task is performed by students for academic credit, Amazon MTurk workers, and Master Amazon MTurk workers. We conclude that the Amazon MTurk and Master Mturk workers perform significantly better than the for-credit students, but with no significant difference between the two MTurk worker types. Furthermore, the quality of the segmentation produced by Amazon MTurk workers rivals that of an expert worker. We provide best practices to assess the quality of ground truth data, and to compare data quality produced by different sources. We conclude that properly managed crowdsourcing can be used to establish large volumes of viable ground truth data at a low cost and high quality, especially in the context of high throughput plant phenotyping. We also provide several metrics for assessing the quality of the generated datasets.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In Gram-positive bacteria, protein precursors with a signal peptide and a cell wall sorting signal (CWSS)-which begins with an LPXTG motif, followed by a hydrophobic domain and a tail of positively ...charged residues-are targeted to the cell envelope by a transpeptidase enzyme call sortase. Evolution and selective pressure gave rise to six classes of sortase, i.e., SrtA-F. Only class C sortases are capable of polymerizing substrates harboring the pilin motif and CWSS into protein polymers known as pili or fimbriae, whereas the others perform cell wall anchoring functions. Regardless of the products generated from these sortases, the basic principle of sortase-catalyzed transpeptidation is the same. It begins with the cleavage of the LPXTG motif, followed by the cross-linking of this cleaved product at the threonine residue to a nucleophile, i.e., an active amino group of the peptidoglycan stem peptide or the lysine residue of the pilin motif. This chapter will summarize the efforts to identify and characterize sortases and their associated pathways with emphasis on the cell wall anchoring function.
The metal-organic framework MOF-5 has attracted significant attention due to its ability to store large quantities of H
2 by mass, up to 10 wt.% absolute at 70 bar and 77 K. On the other hand, since ...MOF-5 is typically obtained as a bulk powder, it exhibits a low volumetric density and poor thermal conductivity—both of which are undesirable characteristics for a hydrogen storage material. Here we explore the extent to which powder densification can overcome these deficiencies, as well as characterize the impact of densification on crystallinity, pore volume, surface area, and crush strength. MOF-5 powder was processed into cylindrical tablets with densities up to 1.6 g/cm
3 by mechanical compaction. We find that optimal hydrogen storage properties are achieved for
ρ ∼ 0.5 g/cm
3, yielding a 350% increase in volumetric H
2 density with only a modest 15% reduction in gravimetric H
2 excess in comparison to the powder. Higher densities result in larger reductions in gravimetric excess. Total pore volume and surface area decrease commensurately with the gravimetric capacity, and are linked to an incipient amorphization transformation. Nevertheless, a large fraction of MOF-5 crystallinity remains intact in densities up to 0.75 g/cm
3, as confirmed from powder XRD. Predictably, the radial crush strength of the pellets is enhanced by densification, increasing by a factor of 4.3 between a density of 0.4 g/cm
3 and 0.6 g/cm
3. Thermal conductivity increases slightly with tablet density, but remains below the single crystal value.
Abstract The existence of a secondary (in addition to compact object mergers) source of heavy element ( r -process) nucleosynthesis, the core-collapse of rapidly rotating and highly magnetized ...massive stars, has been suggested by both simulations and indirect observational evidence. Here, we probe a predicted signature of r -process enrichment, a late-time (≳40 days post-burst) distinct red color, in observations of gamma-ray burst supernovae (GRB-SNe), which are linked to these massive star progenitors. We present optical to near-IR color measurements of four GRB-SNe at z ≲ 0.4, extending out to >500 days post-burst, obtained with the Hubble Space Telescope and large-aperture ground-based telescopes. Comparison of our observations to models indicates that GRBs 030329, 100316D, and 130427A are consistent with both no enrichment and producing 0.01–0.15 M ⊙ of r -process material if there is a low amount of mixing between the inner r -process ejecta and outer supernova (SN) layers. GRB 190829A is not consistent with any models with r -process enrichment ≥0.01 M ⊙ . Taken together the sample of GRB-SNe indicates color diversity at late times. Our derived yields from GRB-SNe may be underestimated due to r -process material hidden in the SN ejecta (potentially due to low mixing fractions) or the limits of current models in measuring r -process mass. We conclude with recommendations for future search strategies to observe and probe the full distribution of r -process produced by GRB-SNe.
Despite a 40% reduction in breast cancer mortality over the last 30 years, not all groups have benefited equally from these gains. A consistent link between later stage of diagnosis and disparities ...in breast cancer mortality has been observed by race, socioeconomic status, and rurality. Therefore, ensuring equitable geographic access to screening mammography represents an important priority for reducing breast cancer disparities. Access to breast cancer screening was evaluated in Delaware, a state that experiences an elevated burden from breast cancer but is otherwise representative of the US in terms of race and urban-rural characteristics. We first conducted a catchment analysis of mammography facilities. Finding evidence of disparities by race and rurality, we next conducted a location-allocation analysis to identify candidate locations for the establishment of new mammography facilities to optimize equitable access.
A catchment analysis using the ArcGIS Pro Service Area analytic tool characterized the geographic distribution of mammography sites and Breast Imaging Centers of Excellence (BICOEs). Poisson regression analyses identified census tract-level correlates of access. Next, the ArcGIS Pro Location-Allocation analytic tool identified candidate locations for the placement of additional mammography sites in Delaware according to several sets of breast cancer screening guidelines.
The catchment analysis showed that for each standard deviation increase in the number of Black women in a census tract, there were 68% (95% CI 38-85%) fewer mammography units and 89% (95% CI 60-98%) fewer BICOEs. The more rural counties in the state accounted for 41% of the population but only 22% of the BICOEs. The results of the location-allocation analysis depended on which set of screening guidelines were adopted, which included increasing mammography sites in communities with a greater proportion of younger Black women and in rural areas.
The results of this study illustrate how catchment and location-allocation analytic tools can be leveraged to guide the equitable selection of new mammography facility locations as part of a larger strategy to close breast cancer disparities.
OBJECTIVES:To determine the rates of psychiatric illness in next of kin following the death of a relative in a medical intensive care unit.
DESIGN:Cross-sectional survey.
SETTING:A university ...teaching hospital, New Haven, CT.
PATIENTS:Forty-one next of kin who had served as primary surrogate decision makers before the death of their loved one in the intensive care unit 3–12 months previously.
INTERVENTIONS:Structured Clinical Interviews for DSM-IV and the Inventory of Complicated Grief–Revised were used to determine prevalence of psychiatric illness. Formal questionnaires were used to evaluate key features of the intensive care unit experience. Bivariate statistics were used to identify factors associated with the presence of psychiatric illness.
MEASUREMENTS AND MAIN RESULTS:Following 107 patient deaths, 51 next of kin were successfully contacted and 41 (80%) agreed to study participation. Thirty-four percent (95% confidence interval, 20% to 51%) met criteria for at least one psychiatric illnessmajor depressive disorder (27%), generalized anxiety disorder (10%), panic disorder (10%), or complicated grief disorder (5%). Disorders were more common in spouses than other kinship relations (63% vs. 16%, p = .002), those experiencing additional stressors after the loss (53% vs. 21%, p = .03), those who said the patient was ill <5 yrs (45% vs. 8%, p = .03), and those who said the patient’s physician was not comforting (71% vs. 23%, p = .02).
CONCLUSIONS:In a cohort of bereaved next of kin of patients who died in the intensive care unit, we identified a high prevalence of psychiatric illness, particularly major depressive disorder. More work is needed to identify those at risk for psychiatric illness so that appropriate interventions may be targeted.
•Bio-optical models extend an HPLC phytoplankton pigment data set to two decades.•Seasonal to decadal dynamics in 5 phytoplankton biomarker pigments are quantified.•Oceanographic and climate forcings ...of biomarker pigment dynamics are assessed.•Decadal dinoflagellate blooms are associated with the NPGO and anomalous advection.•Some small phytoplankton groups respond positively to seasonal upwelling.
The Santa Barbara Channel, CA (SBC) is a biodiverse marine ecosystem fueled largely by phytoplankton productivity, and the composition of the phytoplankton community influences the magnitude and fates of this productivity. Here, we create a 22-year monthly time series of phytoplankton biomarker pigment concentrations in the SBC by combining 12 years of high performance liquid chromatography phytoplankton pigment concentrations with bio-optical models and 10 additional years of bio-optical observations. The bio-optical models skillfully predict biomarker pigment concentrations representative of five distinct phytoplankton groups (PGs; diatoms, dinoflagellates, chlorophytes, prymnesiophytes, and picophytoplankton) and resolve seasonal responses to the annual upwelling-relaxation cycle for all PGs except the dinoflagellates. Our observations indicate that nanophytoplankton groups respond most rapidly to seasonal upwelling, followed by diatoms, and then by picophytoplankton as the water column stratifies in the summer. A Regional Ocean Modeling System (ROMS) solution is used to relate advection of different source waters to the observed PG dynamics. The ROMS simulation results suggest that, on seasonal time scales, pronounced cross-SBC differences in PG seasonality are related to cross-SBC differences in source waters. El Niño Southern Oscillation events drive interannual variability in the upwelling response of most PGs. On decadal time scales, dinoflagellate blooms are associated with the warm phase of the North Pacific Gyre Oscillation and anomalous advection of Southern California Bight source waters into the SBC. Taken together, our results provide a novel view of phytoplankton community succession in response to seasonal upwelling by considering the dynamics of pico- and nano-phytoplankton and suggest that regional surface ocean advection plays a substantial role in driving phytoplankton composition in the SBC.
Summary
Background The RASopathies are a class of human genetic syndromes that are caused by germline mutations in genes which encode components of the Ras/mitogen‐activated protein kinase (MAPK) ...pathway. Cardiofaciocutaneous (CFC) syndrome is characterized by distinctive craniofacial features, congenital heart defects, and abnormalities of the skin and hair.
Objectives Systematically to characterize the spectrum of dermatological findings in mutation‐positive individuals with CFC syndrome.
Methods Dermatological surveys were designed by the authors and distributed to the study participants through CFC International or directly by the authors (K.A.R. and D.H.S.) between July 2006 and August 2009. A second follow‐up survey was collected between December 2007 and August 2009. When available, digital images and medical records of the participants were obtained. Study participants included individuals with CFC syndrome who have a mutation in BRAF, MAP2K1, MAP2K2 or KRAS.
Results Individuals with CFC syndrome have a variety of dermatological manifestations caused by dysregulation of the MAPK pathway in development. Numerous acquired melanocytic naevi were one of the most striking features: more than 50 naevi were reported by 23% (14/61) of participants and of those, more than 100 naevi were reported by 36% (5/14). Keratosis pilaris was reported in 80% (49/61) of cases. Ulerythema ophryogenes was common, occurring in 90% (55/61). Infantile haemangiomas occurred at a greater frequency, 26% (16/61), as compared with the general population.
Conclusions CFC syndrome has a complex dermatological phenotype with many cutaneous features, some of which allow it to be differentiated from the other Ras/MAPK pathway syndromes. Multiple café‐au‐lait macules and papillomas were not identified in this CFC cohort, helping to distinguish CFC from other RASopathies such as neurofibromatosis type 1 and Costello syndrome.
Summary
Background
Actinic keratoses (AKs) are generally accepted as common precursor lesions to invasive squamous cell carcinoma. Photodynamic therapy (PDT) is a common, in‐office, field therapy ...modality used in the treatment of AKs. Clinical and laboratory observations have demonstrated that temperature modulation can affect PDT efficacy.
Objectives
To demonstrate thermal PDT increases apoptotic cell death, and to investigate the mechanistic role of reactive oxygen species (ROS) free radicals in an in vitro human skin fibroblast model.
Methods
This study was completed using commercially available primary human skin fibroblasts treated with aminolaevulinic acid (ALA) at specific concentrations and controlled temperatures. Cell death, apoptosis and superoxide ROS levels were quantified.
Results
We found that thermal PDT with 0·5 mmol L−1 ALA resulted in significant temperature‐dependent increases in total apoptosis and superoxide ROS generation between 33 °C and 42 °C.
Conclusions
Our results indicate that thermal PDT significantly increases apoptotic cell death through increased generation of superoxide ROS in a temperature‐dependent manner.
What's already known about this topic?
Actinic keratoses (AKs) are generally accepted as common precursor lesions to invasive squamous cell carcinoma.
Photodynamic therapy (PDT) is a common field therapy modality used in the treatment of AKs.
Clinical and laboratory observations have demonstrated that thermal modulation can affect PDT efficacy.
The underlying mechanism and cellular effects of thermal PDT are not well characterized from a temporal and biochemical perspective.
What does this study add?
Our findings demonstrate that thermal PDT increases, in a temperature‐dependent manner, superoxide reactive oxygen species generation and percentage of apoptosis‐positive cells.
Temperature‐modulated PDT may represent an enhanced and cost‐effective modality to improve patient compliance and outcomes.
Further in vitro, animal and clinical studies are needed to optimize treatment parameters.
What is the translational message?
We demonstrate that thermal PDT increases superoxide reactive oxygen species generation and percentage of apoptosis‐positive cells in a temperature‐dependent manner.
Temperature‐modulated PDT may represent an enhanced and cost‐effective modality to improve patient compliance and outcomes.
Clinical studies are needed to optimize dosing, incubation period and clinical outcomes.
We hypothesize that our findings will translate to improved patient outcomes and reductions in the burden of disease for AKs.
Linked Comment: Farrar. Br J Dermatol 2016; 175:458–459.
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