938 research outputs found
Explaining interindividual differences in toddlers' collaboration with unfamiliar peers: individual, dyadic, and social factors
During their third year of life, toddlers become increasingly skillful at coordinating their actions with peer partners and they form joint commitments in collaborative situations. However, little effort has been made to explain interindividual differences in collaboration among toddlers. Therefore, we examined the relative influence of distinct individual, dyadic, and social factors on toddlers' collaborative activities (i.e., level of coordination and preference for joint activity) in joint problem-solving situations with unfamiliar peer partners (n = 23 dyads aged M = 35.7 months). We analyzed the dyadic nonindependent data with mixed models. Results indicated that mothers' expectations regarding their children's social behaviors significantly predicted toddlers' level of coordination. Furthermore, the models revealed that toddlers' positive mutual experiences with the unfamiliar partner assessed during an initial free play period (Phase 1) and their level of coordination in an obligatory collaboration task (Phase 2) promoted toddlers' preference for joint activity in a subsequent optional collaboration task (Phase 3). In contrast, children's mastery motivation and shyness conflicted with their collaborative efforts. We discuss the role of parents' socialization goals in toddlers' development toward becoming active collaborators and discuss possible mechanisms underlying the differences in toddlers' commitment to joint activities, namely social preferences and the trust in reliable cooperation partners
Development and validation of a methodology to measure exhaled carbon dioxide (co2) and control indoor air renewal
The measurement of carbon dioxide (CO2) has emerged as a cost-effective and straightforward technique for indirectly managing indoor air quality, aiding in the reduction of the potentially pathogen-laden aerosol concentrations to which we are exposed. Unfortunately, inadequate practices often limit the interpretation of CO2 levels and neglect methodologies that ensure proper air renewal. This study presents a novel methodology for measuring and controlling indoor CO2 levels in shared spaces, comprising four stages: analysis, diagnosis, correction protocols, and monitoring/control/surveillance (MCS). This methodology underwent validation in practical settings, including a cultural center (representing spaces with uniform activities) and 40 commercial spaces (with diverse activities) in Zaragoza, Spain. The results indicate the feasibility of swiftly implementing measures to enhance shared air renewal, with the immediate opening of doors and windows being the most direct solution. The proposed methodology is practical and has the potential to mitigate the risk of the aerosol transmission of respiratory diseases. Consequently, we anticipate that this work will contribute to establishing methodological foundations for CO2 measurement as a valuable, standardized, and reliable tool
Characteristic and necessary minutiae in fingerprints
Fingerprints feature a ridge pattern with moderately varying ridge frequency (RF), following an orientation field (OF), which usually features some singularities. Additionally at some points, called minutiae, ridge lines end or fork and this point pattern is usually used for fingerprint identification and authentication. Whenever the OF features divergent ridge lines (e.g., near singularities), a nearly constant RF necessitates the generation of more ridge lines, originating at minutiae. We call these the necessary minutiae. It turns out that fingerprints feature additional minutiae which occur at rather arbitrary locations. We call these the random minutiae or, since they may convey fingerprint individuality beyond the OF, the characteristic minutiae. In consequence, the minutiae point pattern is assumed to be a realization of the superposition of two stochastic point processes: a Strauss point process (whose activity function is given by the divergence field) with an additional hard core, and a homogeneous Poisson point process, modelling the necessary and the characteristic minutiae, respectively. We perform Bayesian inference using an Markov-Chain-Monte-Carlo (MCMC)-based minutiae separating algorithm (MiSeal). In simulations, it provides good mixing and good estimation of underlying parameters. In application to fingerprints, we can separate the two minutiae patterns and verify by example of two different prints with similar OF that characteristic minutiae convey fingerprint individuality
SARS-CoV-2 Droplet and Airborne Transmission Heterogeneity
The spread dynamics of the SARS-CoV-2 virus have not yet been fully understood after two years of the pandemic. The virus’s global spread represented a unique scenario for advancing infectious disease research. Consequently, mechanistic epidemiological theories were quickly dismissed, and more attention was paid to other approaches that considered heterogeneity in the spread. One of the most critical advances in aerial pathogens transmission was the global acceptance of the airborne model, where the airway is presented as the epicenter of the spread of the disease. Although the aerodynamics and persistence of the SARS-CoV-2 virus in the air have been extensively studied, the actual probability of contagion is still unknown. In this work, the individual heterogeneity in the transmission of 22 patients infected with COVID-19 was analyzed by close contact (cough samples) and air (environmental samples). Viral RNA was detected in 2/19 cough samples from patient subgroups, with a mean Ct (Cycle Threshold in Quantitative Polymerase Chain Reaction analysis) of 25.7 ± 7.0. Nevertheless, viral RNA was only detected in air samples from 1/8 patients, with an average Ct of 25.0 ± 4.0. Viral load in cough samples ranged from 7.3 × 105 to 8.7 × 108 copies/mL among patients, while concentrations between 1.1–4.8 copies/m3 were found in air, consistent with other reports in the literature. In patients undergoing follow-up, no viral load was found (neither in coughs nor in the air) after the third day of symptoms, which could help define quarantine periods in infected individuals. In addition, it was found that the patient’s Ct should not be considered an indicator of infectiousness, since it could not be correlated with the viral load disseminated. The results of this work are in line with proposed hypotheses of superspreaders, which can attribute part of the heterogeneity of the spread to the oversized emission of a small percentage of infected people
Environmental occurrence of the Whipple's disease bacterium (Tropheryma whippelii).
Whipple's disease is a systemic disorder in which a gram-positive rod-shaped bacterium is constantly present in infected tissues. After numerous unsuccessful attempts to culture this bacterium, it was eventually characterized by 16S rRNA gene analysis to be a member of the actinomycetes. The name Tropheryma whippelii was proposed. Until now, the bacterium has only been found in infected human tissues, but there is no evidence for human-to-human transmission. Here we report the detection of DNA specific for the Whipple's disease bacterium in 25 of 38 wastewater samples from five different sewage treatment plants in the area of Heidelberg, Germany. These findings provide the first evidence that T. whippelii occurs in the environment, within a polymicrobial community. This is in accordance with the phylogenetic relationship of this bacterium as well as with known epidemiological aspects of Whipple's disease. Our data argue for an environmental source for infection with the Whipple's disease bacterium
Holocene reef growth and recent carbonate production in the Red Sea
Holocene reef growth, present date bioerosion .and recorded
carbonate production were studied in the fringing
reef at Aqaba, Red Sea. Water depth, wave impact as well
as nutrient availability were considered.
The carbonate production was measured for several coral
samples. Samples of Porites-colonies were collected from
several depths and sites near the Marine Science Station at
Aqaba. Growth rate depends on water depth, size and age
of colonies. Within the coral optimum of water depth growth
rates vary between 5 and 16 mm/yr. Coral carbonate production
was calculated on the base of annual growth increments
and skeletal density using transects from shallow
subtidal down to 40 m water depth. High resolution stable
isotope data were measured to prove the origin of growth
increments. Long-term trends of sea surface temperature
and carbon isotope shift (1800-today) fit to the known global
deviations.
Bioerosion rates were determined using standard dead
coral substrates exposed in different water depths and environmental
settings. Rates vary between 0.6 and
1.4 kg/m2yr. Sediment export evaluated by means of simple
sediment traps ranges between 0.3 and 0.7 kg/m2yr.
Gross carbonate production, mainly built up by scleractinian
corals, amounts to ca. 1.57 kg/m2yr. Bioerosion alters
approx. 1.3 kg/m2yr of hard substrates into sediment. Sediment
export is estimated to be ca. 0.4-0.6 kg/m2yr. Thus a
net production of ca. 0.7 to 0.9 kg/m2yr should remain in the
present reef, which is proved by the recorded carbonate
production (reef drillings). Net production preserved in the
reef can be given with ca. 800 kg/m2kyr (=0.8 kg/m2yr)
Deployment of RDFa, Microdata, and Microformats on the Web – A Quantitative Analysis
More and more websites embed structured data describing for instance
products, reviews, blog posts, people, organizations, events, and cooking recipes
into their HTML pages using markup standards such as Microformats, Microdata
and RDFa. This development has accelerated in the last two years as major Web
companies, such as Google, Facebook, Yahoo!, and Microsoft, have started to
use the embedded data within their applications. In this paper, we analyze the
adoption of RDFa, Microdata, and Microformats across the Web. Our study is
based on a large public Web crawl dating from early 2012 and consisting of 3
billion HTML pages which originate from over 40 million websites. The analysis
reveals the deployment of the different markup standards, the main topical areas
of the published data as well as the different vocabularies that are used within each
topical area to represent data. What distinguishes our work from earlier studies,
published by the large Web companies, is that the analyzed crawl as well as the
extracted data are publicly available. This allows our findings to be verified and to
be used as starting points for further domain-specific investigations as well as for
focused information extraction endeavors
EGF Receptor Signaling Is Essential for K-Ras Oncogene-Driven Pancreatic Ductal Adenocarcinoma
SummaryClinical evidence indicates that mutation/activation of EGF receptors (EGFRs) is mutually exclusive with the presence of K-RAS oncogenes in lung and colon tumors. We have validated these observations using genetically engineered mouse models. However, development of pancreatic ductal adenocarcinomas driven by K-Ras oncogenes are totally dependent on EGFR signaling. Similar results were obtained using human pancreatic tumor cell lines. EGFRs were also essential even in the context of pancreatic injury and absence of p16Ink4a/p19Arf. Only loss of p53 made pancreatic tumors independent of EGFR signaling. Additional inhibition of PI3K and STAT3 effectively prevented proliferation of explants derived from these p53-defective pancreatic tumors. These findings may provide the bases for more rational approaches to treat pancreatic tumors in the clinic
Performance of Chlorella Vulgaris Exposed to Heavy Metal Mixtures: Linking Measured Endpoints and Mechanisms
Microalgae growth inhibition assays are candidates for referent ecotoxicology as a fundamental part of the strategy to reduce the use of fish and other animal models in aquatic toxicology. In the present work, the performance of Chlorella vulgaris exposed to heavy metals following standardized growth and photosynthesis inhibition assays was assessed in two different scenarios: (1) dilutions of single heavy metals and (2) an artificial mixture of heavy metals at similar levels as those found in natural rivers. Chemical speciation of heavy metals was estimated with Visual MINTEQ software; free heavy metal ion concentrations were used as input data, together with microalgae growth and photosynthesis inhibition, to compare different effects and explain possible toxicity mechanisms. The final goal was to assess the suitability of the ecotoxicological test based on the growth and photosynthesis inhibition of microalgae cultures, supported by mathematic models for regulatory and decision-making purposes. The C. vulgaris algae growth inhibition test was more sensitive for As, Zn, and Pb exposure whereas the photosynthesis inhibition test was more sensitive for Cu and Ni exposure. The effects on growth and photosynthesis were not related. C. vulgaris evidenced the formation of mucilaginous aggregations at lower copper concentrations. We found that the toxicity of a given heavy metal is not only determined by its chemical speciation; other chemical compounds (as nutrient loads) and biological interactions play an important role in the final toxicity. Predictive mixture effect models tend to overestimate the effects of metal mixtures in C. vulgaris for both growth and photosynthesis inhibition tests. Growth and photosynthesis inhibition tests give complementary information, and both are a fast, cheap, and sensitive alternative to animal testing. More research is needed to solve the challenge of complex pollutant mixtures as they are present in natural environments, where microalgae-based assays can be suitable monitoring tools for pollution management and regulatory purposes. Keywords: PAM; heavy metal mixtures; metals speciation; microalgae; toxicity
Balanced and Restored Cross-Sections Representing Post-Miocene Crustal Extension of Fluvial Deposits, North-Central Montana to Southeast Idaho
This research is part of a larger project based on the theory of the existence of a pre-ice age, Amazon-scale river that had headwaters in the southern Colorado Plateau and flowed north through the western United States and Canada before discharging into the Labrador Sea. Stream-rounded fluvial deposits in Montana and Idaho provide evidence of sediment provenance in Nevada and Utah, as there are no confirmed bedrock sources for these sediments in Montana or Idaho. The Miocene river bed has been offset and tilted by dozens of extensional faults in the region. Some faults bound large mountain ranges including the Lost River, Lemhi, Beaverhead, Tendoy, Blacktail Deer, Ruby, Madison, and Big Belt Mountains. The reconstructed trend of the Miocene river bed provides a reference line against which to measure active faulting. We constructed five balanced cross-sections of the deformed subsurface along the Miocene river bed from north-central Montana to southeast Idaho across the faulted mountain ranges and restored the cross-sections to represent an un-deformed subsurface. This provided valuable insight into crustal deformation in these regions. Knowing the timing and extent of crustal deformation has many scientific and societal benefits. Western Montana and adjacent Idaho occupy the Inter-mountain Seismic Zone and have the potential for large earthquakes. Detailed cross-sections through this zone can provide information for development projects in faulted areas, and target potential aquifer locations where the thick river gravel has been down-faulted into the sub-surface. This research will be an important contribution to understanding the evolution of the tectonic landscape of Montana and Idaho
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