Significance of durability of mineral fibers for their toxicity and carcinogenic potency in the abdominal cavity of rats in comparison with the low sensitivity of inhalation studies.

At the same time that carcinogenicity of very thin glass fibers after intrapleural and intraperitoneal (ip) administration was demonstrated (1,2) researchers found that gypsum fibers and HCI-leached chrysotile fibers were easily soluble in the peritoneal cavity. This led to the conclusion that the chemical composition of fibers was not responsible for the carcinogenesis but that the degree of carcinogenic potency of a fiber depended on the extent to which it retained its fibrous structure. A thin glass fiber with a low biodurability did not induce tumors after ip injection of a high dose, although the ip test had been criticized for being "overly sensitive." The ip model has been the most successful for determining carcinogenicity of inorganic fibers and establishing dose-response relationships; but to determine the possibilities and limitations of this test model, very high doses of nonfibrous silicon carbide and of a slightly durable glass fiber type were injected ip in Wistar rats. No obviously acute or chronic toxic effect was observed in 90 weeks, but there was a 40% incidence of serosal tumors in the group treated with glass fibers. A pilot study on the persistence of slag fibers in the omentum of rats after ip injection showed a half-time of about 1 year. It was calculated that an ip injection of 10(9) fibers would lead to a concentration of fiber numbers in the ash of the omentum in the same range as the concentration in the lung after 2 years of inhalation exposure. The long-term inhalation study with fibers in rats has been called the "gold standard" for risk characterization.(ABSTRACT TRUNCATED AT 250 WORDS

SAW Sensor for Fastener Failure Detection

The proof of concept for using surface acoustic wave (SAW) strain sensors in the detection of aircraft fastener failures is demonstrated. SAW sensors were investigated because they have the potential for the development of passive wireless systems. The SAW devices employed four orthogonal frequency coding (OFC) spread spectrum reflectors in two banks on a high temperature piezoelectric substrate. Three SAW devices were attached to a cantilever panel with removable side stiffeners. Damage in the form of fastener failure was simulated by removal of bolts from the side stiffeners. During testing, three different force conditions were used to simulate static aircraft structural response under loads. The design of the sensor, the panel arrangement and the panel testing results are reported. The results show that the sensors successfully detected single fastener failure at distances up to 54.6 cm from the failure site under loaded conditions

Dose-response relationship of fibrous dusts in intraperitoneal studies.

The relationship between the number of fibers injected intraperitoneally and the occurrence of peritoneal mesotheliomas in rats was investigated using data from a series of carcinogenicity studies with several fibrous dusts. Based on observed tumor incidences ranging between 10 and 90%, the hypothesis of a common slope of dose-response relationships (parallel probit lines in probit analysis) cannot be rejected. In general, parallelism of probit lines is considered an indication of a common mode of action. Analysis of the shape of the dose-response relationship, with one apparent exception, shows virtually linear or superlinear behavior, i.e., from these data, there is no indication of a decrease in carcinogenic potency of an elementary carcinogenic unit at lower doses

Inferring the Origin Locations of Tweets with Quantitative Confidence

Social Internet content plays an increasingly critical role in many domains, including public health, disaster management, and politics. However, its utility is limited by missing geographic information; for example, fewer than 1.6% of Twitter messages (tweets) contain a geotag. We propose a scalable, content-based approach to estimate the location of tweets using a novel yet simple variant of gaussian mixture models. Further, because real-world applications depend on quantified uncertainty for such estimates, we propose novel metrics of accuracy, precision, and calibration, and we evaluate our approach accordingly. Experiments on 13 million global, comprehensively multi-lingual tweets show that our approach yields reliable, well-calibrated results competitive with previous computationally intensive methods. We also show that a relatively small number of training data are required for good estimates (roughly 30,000 tweets) and models are quite time-invariant (effective on tweets many weeks newer than the training set). Finally, we show that toponyms and languages with small geographic footprint provide the most useful location signals.Comment: 14 pages, 6 figures. Version 2: Move mathematics to appendix, 2 new references, various other presentation improvements. Version 3: Various presentation improvements, accepted at ACM CSCW 201

CTMC calculations of electron capture and ionization in collisions of multiply charged ions with elliptical Rydberg atoms

We have performed classical trajectory Monte Carlo (CTMC) studies of electron capture and ionization in multiply charged (Q=8) ion-Rydberg atom collisions at intermediate impact velocities. Impact parallel to the minor and to the major axis, respectively, of the initial Kepler electron ellipse has been investigated. The important role of the initial electron momentum distribution found for singly charged ion impact is strongly disminished for higher projectile charge, while the initial spatial distribution remains important for all values of Q studied.Comment: 3 pages, 5 figure

DNA-based Self-Assembly of Chiral Plasmonic Nanostructures with Tailored Optical Response

Surface plasmon resonances generated in metallic nanostructures can be utilized to tailor electromagnetic fields. The precise spatial arrangement of such structures can result in surprising optical properties that are not found in any naturally occurring material. Here, the designed activity emerges from collective effects of singular components equipped with limited individual functionality. Top-down fabrication of plasmonic materials with a predesigned optical response in the visible range by conventional lithographic methods has remained challenging due to their limited resolution, the complexity of scaling, and the difficulty to extend these techniques to three-dimensional architectures. Molecular self-assembly provides an alternative route to create such materials which is not bound by the above limitations. We demonstrate how the DNA origami method can be used to produce plasmonic materials with a tailored optical response at visible wavelengths. Harnessing the assembly power of 3D DNA origami, we arranged metal nanoparticles with a spatial accuracy of 2 nm into nanoscale helices. The helical structures assemble in solution in a massively parallel fashion and with near quantitative yields. As a designed optical response, we generated giant circular dichroism and optical rotary dispersion in the visible range that originates from the collective plasmon-plasmon interactions within the nanohelices. We also show that the optical response can be tuned through the visible spectrum by changing the composition of the metal nanoparticles. The observed effects are independent of the direction of the incident light and can be switched by design between left- and right-handed orientation. Our work demonstrates the production of complex bulk materials from precisely designed nanoscopic assemblies and highlights the potential of DNA self-assembly for the fabrication of plasmonic nanostructures.Comment: 5 pages, 4 figure

Rethinking palliative care in a public health context: addressing the needs of persons with non-communicable chronic diseases

Non-communicable chronic diseases (NCCDs) are the main cause of morbidity and mortality globally. Demographic aging has resulted in older populations with more complex healthcare needs. This necessitates a multilevel rethinking of healthcare policies, health education and community support systems with digitalization of technologies playing a central role. The European Innovation Partnership on Active and Healthy Aging (A3) working group focuses on well-being for older adults, with an emphasis on quality of life and healthy aging. A subgroup of A3, including multidisciplinary stakeholders in health care across Europe, focuses on the palliative care (PC) model as a paradigm to be modified to meet the needs of older persons with NCCDs. This development paper delineates the key parameters we identified as critical in creating a public health model of PC directed to the needs of persons with NCCDs. This paradigm shift should affect horizontal components of public health models. Furthermore, our model includes vertical components often neglected, such as nutrition, resilience, well-being and leisure activities. The main enablers identified are information and communication technologies, education and training programs, communities of compassion, twinning activities, promoting research and increasing awareness amongst policymakers. We also identified key 'bottlenecks': inequity of access, insufficient research, inadequate development of advance care planning and a lack of co-creation of relevant technologies and shared decision-making. Rethinking PC within a public health context must focus on developing policies, training and technologies to enhance person-centered quality life for those with NCCD, while ensuring that they and those important to them experience death with dignity

Unraveling the complexity of tyrosine kinase inhibitor-resistant populations by ultra-deep sequencing of the BCR-ABL kinase domain

In chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, tyrosine kinase inhibitor (TKI) therapy may select for drug-resistant BCR-ABL mutants. We used an ultra-deep sequencing (UDS) approach to resolve qualitatively and quantitatively the complexity of mutated populations surviving TKIs and to investigate their clonal structure and evolution over time in relation to therapeutic intervention. To this purpose, we performed a longitudinal analysis of 106 samples from 33 patients who had received sequential treatment with multiple TKIs and had experienced sequential relapses accompanied by selection of 1 or more TKI-resistant mutations. We found that conventional Sanger sequencing had misclassified or underestimated BCR-ABL mutation status in 55% of the samples, where mutations with 1% to 15% abundance were detected. A complex clonal texture was uncovered by clonal analysis of samples harboring multiple mutations and up to 13 different mutated populations were identified. The landscape of these mutated populations was found to be highly dynamic. The high degree of complexity uncovered by UDS indicates that conventional Sanger sequencing might be an inadequate tool to assess BCR-ABL kinase domain mutation status, which currently represents an important component of the therapeutic decision algorithms. Further evaluation of the clinical usefulness of UDS-based approaches is warranted