Screening mammography aims to identify breast cancer at earlier stages of the disease, when treatment can be more successful
. Despite the existence of screening programmes worldwide, the ...interpretation of mammograms is affected by high rates of false positives and false negatives
. Here we present an artificial intelligence (AI) system that is capable of surpassing human experts in breast cancer prediction. To assess its performance in the clinical setting, we curated a large representative dataset from the UK and a large enriched dataset from the USA. We show an absolute reduction of 5.7% and 1.2% (USA and UK) in false positives and 9.4% and 2.7% in false negatives. We provide evidence of the ability of the system to generalize from the UK to the USA. In an independent study of six radiologists, the AI system outperformed all of the human readers: the area under the receiver operating characteristic curve (AUC-ROC) for the AI system was greater than the AUC-ROC for the average radiologist by an absolute margin of 11.5%. We ran a simulation in which the AI system participated in the double-reading process that is used in the UK, and found that the AI system maintained non-inferior performance and reduced the workload of the second reader by 88%. This robust assessment of the AI system paves the way for clinical trials to improve the accuracy and efficiency of breast cancer screening.
Global warming is forcing many species to shift their distributions upward, causing consequent changes in the compositions of species that occur at specific locations. This prediction remains largely ...untested for tropical trees. Here we show, using a database of nearly 200 Andean forest plot inventories spread across more than 33.5° latitude (from 26.8° S to 7.1° N) and 3,000-m elevation (from 360 to 3,360 m above sea level), that tropical and subtropical tree communities are experiencing directional shifts in composition towards having greater relative abundances of species from lower, warmer elevations. Although this phenomenon of 'thermophilization' is widespread throughout the Andes, the rates of compositional change are not uniform across elevations. The observed heterogeneity in thermophilization rates is probably because of different warming rates and/or the presence of specialized tree communities at ecotones (that is, at the transitions between distinct habitats, such as at the timberline or at the base of the cloud forest). Understanding the factors that determine the directions and rates of compositional changes will enable us to better predict, and potentially mitigate, the effects of climate change on tropical forests.
(IPI)Ru(II)(OH) n (H2O) m , 2, where IPI is the NNN-pincer ligand, 2,6-diimidizoylpyridine, is shown to catalyze H/D exchange between hydrocarbons and strongly basic solvents at higher rates than in ...the case of the solvent alone. Significantly, catalysis by 2 is accelerated rather than inhibited by increasing solvent basicity. The evidence is consistent with the reaction proceeding by base modulated nucleophilic CH activation.
Although species have always shifted their ranges, the rapid pace of current biophysical changes and the further complications imparted by human land use provide unprecedented challenges for ...biodiversity conservation. As a result, goals, methods, and strategies are being reconceptualized. For example, the terms conservation and wilderness protection, and their associated practices, seem to be static and simplistic compared to the challenges of managing novel species assemblages in unique climatic and disturbance regimes. A more proactive approach is developing that builds in the needed adaptations as biophysical change progressed; that would need to consider possible nonlinear ecosystem changes, with threshold effects and ecological surprises; that might force a reconsideration of the goals of ecological restoration; and that might require management of lands today for goals that could be quite different in 50 to 100 years. As examples, this could require such potentially controversial activities as planting trees outside their ranges so that they could serve as part of wildlife habitat in several decades, using prescribed burns, or bringing some species into captivity or botanical gardens until reintroduction becomes feasible. With the Anthropocene providing a potential new label for the current epoch and ongoing research providing new insights into disturbance regimes and successful conservation practices, it is appropriate to rethink implications for sustainability and human-nature relationships in general and for biodiversity in particular.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Savanna landscapes are shaped by the interactions of disturbances with land use goals. Elephant hunting in a site in Botswana, and its consequences for wildlife, people, and landscapes, are described ...and discussed in order to make broader generalizations about the dynamics of savanna landscapes. Change comes from alterations in tree-grass interactions, fire regimes, predator-prey relations, livestock raising, and conservation goals. Some of these implications are specific to African landscapes, but others may be apt in global contexts.
Human tyrosinase (hTyr) is a Type 1 membrane bound glycoenzyme that catalyzes the initial and rate-limiting steps of melanin production in the melanosome. Mutations in the Tyr gene are linked to ...oculocutaneous albinism type 1 (OCA1), an autosomal recessive disorder. Currently, the application of enzyme replacement therapy for a treatment of OCA1 is hampered by the absence of pure hTyr. Here, full-length hTyr (residues 1-529) was overexpressed in Trichoplusia ni larvae infected with a baculovirus, solubilized with detergent and purified using chromatography. Michaelis-Menten kinetics, enzymatic specific activity, and analytical ultracentrifugation were used to compare the hTyr in detergent with the soluble recombinant intra-melanosomal domain, hTyrCtr (residues 19-469). Active hTyr is monomeric in detergent micelles suggesting no stable interactions between protein molecules. Both, hTyr and hTyrCtr, exhibited similar enzymatic activity and ligand affinity in L-DOPA and L-Tyrosine reactions. In addition, expression in larvae is a scalable process that will allow high yield protein production. Thus, larval production of enzymatically active human tyrosinase potentially could be a useful tool in developing a cure for OCA1.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Chiropractors use words and phrases in unique ways to express traditional, chiropractic-specific theories. This lexicon represents concepts that reinforce the separation of chiropractic from other ...health care professions. It may impact referrals both to and from chiropractors, lead to public confusion about health care issues, and reduce cross-disciplinary research. Therefore, it is important to understand how prevalent chiropractic-specific terms are in publicly available media.
Five chiropractic terms were selected: subluxation, adjustment, vital (-ism/-istic), wellness, and Innate (Intelligence). States and territories in Australia were proportionately sampled according to population of chiropractors using a Google search for chiropractors' private practice websites. The top results were recorded. Websites were word-searched on every publicly available page for the five terms. Context was checked to count only terms that were used to support a chiropractic-specific concepts. The number of occurrences of each term was recorded, tallied nationally and by state/territory. Descriptive statistics were applied to determine prevalence.
Three hundred sixty-nine websites were sampled, based on an estimate of 5500 chiropractors practising in Australia. Nationally, 85% of chiropractors used one or more terms. The term adjust (-ing/-ment) occurred most frequently, being found on 283 websites (77%) with a total of 2249 occurrences. Wellness was found on 199 websites (54%) with 872 occurrences; subluxation was found on 104 websites (28%), 489 occurrences; vital (-ism/-istic) on 71 websites (19%) with 158 occurrences; and Innate was least used, being found on 39 websites (11%) with 137 occurrences.
A majority of the Australian chiropractors sampled used one or more chiropractic-specific terms on their websites. Future research should explore the effects of chiropractic language on the public, policy-makers, and other health care professionals.
Knowledge of x-ray attenuation is essential for developing and evaluating x-ray imaging technologies. In mammography, measurement of breast density, dose estimation, and differentiation between cysts ...and solid tumours are example applications requiring accurate data on tissue attenuation. Published attenuation data are, however, sparse and cover a relatively wide range. To supplement available data we have previously measured the attenuation of cyst fluid and solid lesions using photon-counting spectral mammography. The present study aims to measure the attenuation of normal adipose and glandular tissue, and to measure the effect of formalin fixation, a major uncertainty in published data. A total of 27 tumour specimens, seven fibro-glandular tissue specimens, and 15 adipose tissue specimens were included. Spectral (energy-resolved) images of the samples were acquired and the image signal was mapped to equivalent thicknesses of two known reference materials, from which x-ray attenuation as a function of energy can be derived. The spread in attenuation between samples was relatively large, partly because of natural variation. The variation of malignant and glandular tissue was similar, whereas that of adipose tissue was lower. Formalin fixation slightly altered the attenuation of malignant and glandular tissue, whereas the attenuation of adipose tissue was not significantly affected. The difference in attenuation between fresh tumour tissue and cyst fluid was smaller than has previously been measured for fixed tissue, but the difference was still significant and discrimination of these two tissue types is still possible. The difference between glandular and malignant tissue was close-to significant; it is reasonable to expect a significant difference with a larger set of samples. We believe that our studies have contributed to lower the overall uncertainty of breast tissue attenuation in the literature due to the relatively large sample sets, the novel measurement method, and by clarifying the difference between fresh and fixed tissue.
Tyrosinases are melanocyte‐specific enzymes involved in melanin biosynthesis. Mutations in their genes cause oculocutaneous albinism associated with reduced or altered pigmentation of skin, hair, and ...eyes. Here, the recombinant human intra‐melanosomal domains of tyrosinase, TYRtr (19–469), and tyrosinase‐related protein 1, TYRP1tr (25–472), were studied in vitro to define their functional relationship. Proteins were expressed or coexpressed in whole Trichoplusia ni larvae and purified. Their associations were studied using gel filtration and sedimentation equilibrium methods. Protection of TYRtr was studied by measuring the kinetics of tyrosinase diphenol oxidase activity in the presence (1:1 and 1:20 molar ratios) or the absence of TYRP1tr for 10 hr under conditions mimicking melanosomal and ER pH values. Our data indicate that TYRtr incubation with excess TYRP1tr protects TYR, increasing its stability over time. However, this mechanism does not appear to involve the formation of stable hetero‐oligomeric complexes to maintain the protective function.
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