541 research outputs found
Numerical investigation of airborne contaminant transport under different vortex structures in the aircraft cabin.
Airborne contaminants such as pathogens, odors and CO2 released from an individual passenger could spread via air flow in an aircraft cabin and make other passengers unhealthy and uncomfortable. In this study, we introduced the airflow vortex structure to analyze how airflow patterns affected contaminant transport in an aircraft cabin. Experimental data regarding airflow patterns were used to validate a computational fluid dynamics (CFD) model. Using the validated CFD model, we investigated the effects of the airflow vortex structure on contaminant transmission based on quantitative analysis. It was found that the contaminant source located in a vorticity-dominated region was more likely to be "locked" in the vortex, resulting in higher 62% higher average concentration and 14% longer residual time than that when the source was on a deformation dominated location. The contaminant concentrations also differed between the front and rear parts of the cabin because of different airflow structures. Contaminant released close to the heated manikin face was likely to be transported backward according to its distribution mean position. Based on these results, the air flow patterns inside aircraft cabins can potentially be improved to better control the spread of airborne contaminant
Pulmonary diseases induced by ambient ultrafine and engineered nanoparticles in twenty-first century.
Air pollution is a severe threat to public health globally, affecting everyone in developed and developing countries alike. Among different air pollutants, particulate matter (PM), particularly combustion-produced fine PM (PM2.5) has been shown to play a major role in inducing various adverse health effects. Strong associations have been demonstrated by epidemiological and toxicological studies between increases in PM2.5 concentrations and premature mortality, cardiopulmonary diseases, asthma and allergic sensitization, and lung cancer. The mechanisms of PM-induced toxicological effects are related to their size, chemical composition, lung clearance and retention, cellular oxidative stress responses and pro-inflammatory effects locally and systemically. Particles in the ultrafine range (<100 nm), although they have the highest number counts, surface area and organic chemical content, are often overlooked due to insufficient monitoring and risk assessment. Yet, ample studies have demonstrated that ambient ultrafine particles have higher toxic potential compared with PM2.5. In addition, the rapid development of nanotechnology, bringing ever-increasing production of nanomaterials, has raised concerns about the potential human exposure and health impacts. All these add to the complexity of PM-induced health effects that largely remains to be determined, and mechanistic understanding on the toxicological effects of ambient ultrafine particles and nanomaterials will be the focus of studies in the near future
Blood Pressure Control Goals in Elderly Patients with Hypertension:Evidence from Latest Clinical Studies
Due to the lack of relevant research evidence, the optimal blood pressure target in elderly hypertensive patients has been controversial for a long time. Many scholars believe that the elderly have poor tolerance to antihypertensive treatment, so their blood pressure control goal should bemore relaxed. However, the latest research evidence published in recent years shows that there may be more benefits from controlling systolic blood pressure in older adults to <130 mmHg. It is expected that these new research conclusions will have an important impact on the revision of guidelines in the future
HAMNER: Headword Amplified Multi-span Distantly Supervised Method for Domain Specific Named Entity Recognition
To tackle Named Entity Recognition (NER) tasks, supervised methods need to
obtain sufficient cleanly annotated data, which is labor and time consuming. On
the contrary, distantly supervised methods acquire automatically annotated data
using dictionaries to alleviate this requirement. Unfortunately, dictionaries
hinder the effectiveness of distantly supervised methods for NER due to its
limited coverage, especially in specific domains. In this paper, we aim at the
limitations of the dictionary usage and mention boundary detection. We
generalize the distant supervision by extending the dictionary with headword
based non-exact matching. We apply a function to better weight the matched
entity mentions. We propose a span-level model, which classifies all the
possible spans then infers the selected spans with a proposed dynamic
programming algorithm. Experiments on all three benchmark datasets demonstrate
that our method outperforms previous state-of-the-art distantly supervised
methods.Comment: 9 pages, 2 figure
Spectroscopic study of light scattering in linear alkylbenzene for liquid scintillator neutrino detectors
We has set up a light scattering spectrometer to study the depolarization of
light scattering in linear alkylbenzene. From the scattering spectra it can be
unambiguously shown that the depolarized part of light scattering belongs to
Rayleigh scattering. The additional depolarized Rayleigh scattering can make
the effective transparency of linear alkylbenzene much better than it was
expected. Therefore sufficient scintillation photons can transmit through the
large liquid scintillator detector of JUNO. Our study is crucial to achieving
the unprecedented energy resolution 3\%/ for JUNO
experiment to determine the neutrino mass hierarchy. The spectroscopic method
can also be used to judge the attribution of the depolarization of other
organic solvents used in neutrino experiments.Comment: 6 pages, 5 figure
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