6,080 research outputs found
Lung function decline in 4-monthly repeated spirometric measurements: Due to silt aerosol exposure or decreasing effort?
Background: Workers on dredgers and lighters on rivers are exposed to the inhalation of aerosols and dusts. Objective: The aim of this study was to investigate effects of river silt aerosol and dust exposure on the respiratory health of dredging employees. Methods: Six era mi nations were performed over a period of 2 years at 4-monthly intervals in 54 seamen with higher silt aerosol exposure and 36 controls of the same employer. Results: No significant differences could be observed between the groups at any time of the study but there was an unexpected significant decrease in the age-corrected expiratory vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and midexpiratory flow rate (MMEF25/75) over the six series in both groups. This may indicate a loss of effort of the participants in re-examinations since biological and technical influences were highly unlikely to be the cause of these findings. Conclusions: Ignoring this possible decline of effort in frequently repeated measurements may result in overestimating potential effects of occupational exposure. Copyright (C) 2000 S. Karger AG, Basel
Stochastic thermodynamics for Ising chain and symmetric exclusion process
We verify the finite time fluctuation theorem for a linear Ising chain at its
ends in contact with heat reservoirs. Analytic results are derived for a chain
consisting of only two spins. The system can be mapped onto a model for
particle transport, namely the symmetric exclusion process, in contact with
thermal and particle reservoirs. We modify the symmetric exclusion process to
represent a thermal engine and reproduce universal features of the efficiency
at maximum power
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Titanocene anticancer complexes and their binding mode of action to human serum albumin: a computational study
Due to the pivotal role played by human serum albumin (HSA) in the transport and cytotoxicity of titanocene complexes, a docking study has been performed on a selected set of titanocene complexes to aid in the current understanding of the potential mode of action of these titanocenes upon binding HSA. Analysis of the docking results has revealed potential binding at the known drug binding sites in HSA and has provided some explanation for the specificity and subsequent cytotoxicity of these titanocenes. Additionally, a new alternative binding site for these titanocenes has been postulated
Universality of efficiency at maximum power
We investigate the efficiency of power generation by thermo-chemical engines.
For strong coupling between the particle and heat flows and in the presence of
a left-right symmetry in the system, we demonstrate that the efficiency at
maximum power displays universality up to quadratic order in the deviation from
equilibrium. A maser model is presented to illustrate our argument.Comment: 4 pages, 2 figure
Hyphal growth of phagocytosed fusarium oxysporum causes cell lysis and death of murine macrophages
Peer reviewedPublisher PD
Studying Gender in Conference Talks -- data from the 223rd meeting of the American Astronomical Society
We present a study on the gender balance, in speakers and attendees, at the
recent major astronomical conference, the American Astronomical Society meeting
223, in Washington, DC. We conducted an informal survey, yielding over 300
responses by volunteers at the meeting. Each response included gender data
about a single talk given at the meeting, recording the gender of the speaker
and all question-askers. In total, 225 individual AAS talks were sampled. We
analyze basic statistical properties of this sample. We find that the gender
ratio of the speakers closely matched the gender ratio of the conference
attendees. The audience asked an average of 2.8 questions per talk. Talks given
by women had a slightly higher number of questions asked (3.20.2) than
talks given by men (2.60.1). The most significant result from this study
is that while the gender ratio of speakers very closely mirrors that of
conference attendees, women are under-represented in the question-asker
category. We interpret this to be an age-effect, as senior scientists may be
more likely to ask questions, and are more commonly men. A strong dependence on
the gender of session chairs is found, whereby women ask disproportionately
fewer questions in sessions chaired by men. While our results point to laudable
progress in gender-balanced speaker selection, we believe future surveys of
this kind would help ensure that collaboration at such meetings is as inclusive
as possible.Comment: 4 pages, 5 figures. Comments welcome
Uptake and fecal excretion of Coxiella burnetii by Ixodes ricinus and Dermacentor marginatus ticks
Background:
The bacterium Coxiella burnetii is the etiological agent of Q fever and is mainly transmitted via inhalation of infectious aerosols. DNA of C. burnetii is frequently detected in ticks, but the role of ticks as vectors in the epidemiology of this agent is still controversial. In this study, Ixodes ricinus and Dermacentor marginatus adults as well as I. ricinus nymphs were fed on blood spiked with C. burnetii in order to study the fate of the bacterium within putative tick vectors.
Methods:
Blood-feeding experiments were performed in vitro in silicone-membrane based feeding units. The uptake, fecal excretion and transstadial transmission of C. burnetii was examined by quantitative real-time PCR as well as cultivation of feces and crushed tick filtrates in L-929 mouse fibroblast cells and cell-free culture medium.
Results:
Ticks successfully fed in the feeding system with engorgement rates ranging from 29% (D. marginatus) to 64% (I. ricinus adults). Coxiella burnetii DNA was detected in the feces of both tick species during and after feeding on blood containing 105 or 106 genomic equivalents per ml blood (GE/ml), but not when fed on blood containing only 104 GE/ml. Isolation and cultivation demonstrated the infectivity of C. burnetii in shed feces. In 25% of the I. ricinus nymphs feeding on inoculated blood, a transstadial transmission to the adult stage was detected. Females that molted from nymphs fed on inoculated blood excreted C. burnetii of up to 106 genomic equivalents per mg of feces.
Conclusions:
These findings show that transstadial transmission of C. burnetii occurs in I. ricinus and confirm that I. ricinus is a potential vector for Q fever. Transmission from both tick species might occur by inhalation of feces containing high amounts of viable C. burnetii rather than via tick bites
Memory-induced anomalous dynamics: emergence of diffusion, subdiffusion, and superdiffusion from a single random walk model
We present a random walk model that exhibits asymptotic subdiffusive,
diffusive, and superdiffusive behavior in different parameter regimes. This
appears to be the first instance of a single random walk model leading to all
three forms of behavior by simply changing parameter values. Furthermore, the
model offers the great advantage of analytic tractability. Our model is
non-Markovian in that the next jump of the walker is (probabilistically)
determined by the history of past jumps. It also has elements of intermittency
in that one possibility at each step is that the walker does not move at all.
This rich encompassing scenario arising from a single model provides useful
insights into the source of different types of asymptotic behavior
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