873 research outputs found
Incidence, duration, and determinants of cervical Human Papillomavirus infection in a cohort of Colombian women with normal Cytological results
Q1Q1Data on the incidence and determinants of human papillomavirus (HPV) infection in women 130 years old are
scarce. To address this, a cohort of 1610 women—15–85 years old, HPV negative, and with normal cytological
results at baseline—was monitored every 6 months for an average of 4.1 years. Information on risk factors and
cervical samples for cytological testing and detection and typing of HPV DNA were obtained at each visit. The
incidence of high-risk types was higher than that of low-risk types (5.0 vs. 2.0 cases/100 woman-years). The agespecific incidence curve for high-risk types was bimodal, whereas the incidence of low-risk types gradually
decreased with age. Infections with high-risk types lasted longer than infections with low-risk types (14.8 vs. 11.1
months). In this cohort of cytologically normal women, the incidence of cervical HPV infection was high, and
the epidemiological profile of high-risk HPV types was different from that of low-risk typeshttp://scienti.colciencias.gov.co:8081/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0000266264https://scienti.minciencias.gov.co/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0000017647https://scienti.minciencias.gov.co/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0001240307Revista Nacional - Indexad
Quantitative analysis of regulatory flexibility under changing environmental conditions
The circadian clock controls 24-h rhythms in many biological processes, allowing appropriate timing of biological rhythms relative to dawn and dusk. Known clock circuits include multiple, interlocked feedback loops. Theory suggested that multiple loops contribute the flexibility for molecular rhythms to track multiple phases of the external cycle. Clear dawn- and dusk-tracking rhythms illustrate the flexibility of timing in Ipomoea nil. Molecular clock components in Arabidopsis thaliana showed complex, photoperiod-dependent regulation, which was analysed by comparison with three contrasting models. A simple, quantitative measure, Dusk Sensitivity, was introduced to compare the behaviour of clock models with varying loop complexity. Evening-expressed clock genes showed photoperiod-dependent dusk sensitivity, as predicted by the three-loop model, whereas the one- and two-loop models tracked dawn and dusk, respectively. Output genes for starch degradation achieved dusk-tracking expression through light regulation, rather than a dusk-tracking rhythm. Model analysis predicted which biochemical processes could be manipulated to extend dusk tracking. Our results reveal how an operating principle of biological regulators applies specifically to the plant circadian clock
Cervical coinfection with Human Papillomavirus (HPV) types and possible implications for the prevention of cervical cancer by HPV vaccines
Q1Q1http://scienti.colciencias.gov.co:8081/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0000266264https://scienti.minciencias.gov.co/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0000017647https://scienti.minciencias.gov.co/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0001240307Revista Nacional - Indexad
Dark-adapted red flash ERGs in healthy adults
Purpose: The x-wave of the dark-adapted (DA) ERG to a red flash reflects DA cone function. This exploratory study of healthy adults aimed to investigate changes in the DA red ERG with flash strength and during dark adaptation to optimise visualisation and therefore quantification of the x-wave.
Methods: The effect of altering red flash strength was investigated in four subjects by recording ERGs after 20 minutes dark adaptation to red flashes (0.2–2.0 cd s m-2) using skin electrodes and natural pupils. The effect of dark adaptation duration was investigated in 16 subjects during 20 minutes in the dark, by recording DA 1.5 red ERGs at 1, 2, 3, 4, 5, 10, 15 and 20 minutes.
Results: For a dark adaption period of 20 minutes, the x-wave was more clearly visualised to weaker (< 0.6 cd s m-2) red flash strengths: to stronger flashes it became obscured by the b-wave. For red flashes of 1.5 cd s m-2, the x-wave was most prominent in ERGs recorded after 1–5 minutes of dark adaptation: with longer dark-adaptation, it was subsumed into the b-wave’s rising edge.
Conclusions: This small study suggests that x-wave visibility in healthy subjects after 20 minutes dark adaptation is improved by using flashes weaker than around 0.6 cd s m-2; for flash strengths of 1.5 cd s m-2, x-wave visibility is enhanced by recording after only around 5 minutes of dark adaptation. No evidence was found that interim red flash ERGs affecting the dark-adapted state of the normal retina
Wake Development behind Paired Wings with Tip and Root Trailing Vortices: Consequences for Animal Flight Force Estimates
Recent experiments on flapping flight in animals have shown that a variety of unrelated species shed a wake behind left and right wings consisting of both tip and root vortices. Here we present an investigation using Particle Image Velocimetry (PIV) of the behaviour and interaction of trailing vortices shed by paired, fixed wings that simplify and mimic the wake of a flying animal with a non-lifting body. We measured flow velocities at five positions downstream of two adjacent NACA 0012 aerofoils and systematically varied aspect ratio, the gap between the wings (corresponding to the width of a non-lifting body), angle of attack, and the Reynolds number. The range of aspect ratios and Reynolds number where chosen to be relevant to natural fliers and swimmers, and insect flight in particular. We show that the wake behind the paired wings deformed as a consequence of the induced flow distribution such that the wingtip vortices convected downwards while the root vortices twist around each other. Vortex interaction and wake deformation became more pronounced further downstream of the wing, so the positioning of PIV measurement planes in experiments on flying animals has an important effect on subsequent force estimates due to rotating induced flow vectors. Wake deformation was most severe behind wings with lower aspect ratios and when the distance between the wings was small, suggesting that animals that match this description constitute high-risk groups in terms of measurement error. Our results, therefore, have significant implications for experimental design where wake measurements are used to estimate forces generated in animal flight. In particular, the downstream distance of the measurement plane should be minimised, notwithstanding the animal welfare constraints when measuring the wake behind flying animals
Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis
This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting,
and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419882500.[EN] Diesel spray modeling is a multi-scale problem with complex interactions between different flow regions, that is, internal nozzle flow, near-nozzle region and developed spray, including evaporation and combustion. There are several modeling approaches that have proven particularly useful for some spray regions although they have struggled at other areas, while Eulerian modeling has shown promise in dealing with all characteristics at a reasonable computational effort for engineering calculations. In this work, the sigma -Y single-fluid diffuse-interface model, based on scale separation assumptions at high Reynolds and Weber numbers, is used to simulate the engine combustion network Sprays A and D within a Reynolds-averaged Navier-Stokes turbulence modeling approach. The study is divided into two parts. First of all, the larger diameter Spray D is modeled from the nozzle flow till evaporative spray conditions, obtaining successful prediction of numerous spray metrics, paying special attention to the near-nozzle region where spray dispersion and interfacial surface area can be validated against measurements conducted at the Advanced Photon Source at Argonne National Laboratory, including both the ultra-small-angle X-ray scattering and the X-ray radiography. Afterwards, an analysis of the modeling predictions is made in comparison with previous results obtained for Spray A, considering the nozzle geometry effects in the modeling behavior.The authors thank the freely shared X-ray radiography and ultra-small-angle X-ray scattering measurements performed at Argonne National Laboratory by the following authors: Daniel J. Duke, Jan Ilavsky, Katarzyna E. Matusik., Brandon A. Sforzo., Alan L. Kastengren and Christopher F. Powell. They also thankfully acknowledge the computer resources at Picasso and the technical support provided by Universidad de Malaga (UMA; RES-FI-2018-1-0039).Pandal, A.; García-Oliver, JM.; Pastor Enguídanos, JM. (2020). Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis. International Journal of Engine Research. 21(1):73-88. https://doi.org/10.1177/1468087419882500S7388211PAYRI, R., GARCIA, J., SALVADOR, F., & GIMENO, J. (2005). 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M., Pastor, J. M., Pandal, A., Baldwin, E., & Schmidt, D. P. (2016). Coupled/decoupled spray simulation comparison of the ECN spray a condition with the -Y Eulerian atomization model. International Journal of Multiphase Flow, 80, 89-99. doi:10.1016/j.ijmultiphaseflow.2015.12.002Garcia-Oliver, J. M., Pastor, J. M., Pandal, A., Trask, N., Baldwin, E., & Schmidt, D. P. (2013). DIESEL SPRAY CFD SIMULATIONS BASED ON THE Σ-Υ EULERIAN ATOMIZATION MODEL. Atomization and Sprays, 23(1), 71-95. doi:10.1615/atomizspr.2013007198Navarro-Martinez, S. (2014). Large eddy simulation of spray atomization with a probability density function method. International Journal of Multiphase Flow, 63, 11-22. doi:10.1016/j.ijmultiphaseflow.2014.02.013Pandal, A., Pastor, J. M., García-Oliver, J. M., Baldwin, E., & Schmidt, D. P. (2016). A consistent, scalable model for Eulerian spray modeling. 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SynthRAD2023 Grand Challenge dataset: generating synthetic CT for radiotherapy
Purpose: Medical imaging has become increasingly important in diagnosing and
treating oncological patients, particularly in radiotherapy. Recent advances in
synthetic computed tomography (sCT) generation have increased interest in
public challenges to provide data and evaluation metrics for comparing
different approaches openly. This paper describes a dataset of brain and pelvis
computed tomography (CT) images with rigidly registered CBCT and MRI images to
facilitate the development and evaluation of sCT generation for radiotherapy
planning.
Acquisition and validation methods: The dataset consists of CT, CBCT, and MRI
of 540 brains and 540 pelvic radiotherapy patients from three Dutch university
medical centers. Subjects' ages ranged from 3 to 93 years, with a mean age of
60. Various scanner models and acquisition settings were used across patients
from the three data-providing centers. Details are available in CSV files
provided with the datasets.
Data format and usage notes: The data is available on Zenodo
(https://doi.org/10.5281/zenodo.7260705) under the SynthRAD2023 collection. The
images for each subject are available in nifti format.
Potential applications: This dataset will enable the evaluation and
development of image synthesis algorithms for radiotherapy purposes on a
realistic multi-center dataset with varying acquisition protocols. Synthetic CT
generation has numerous applications in radiation therapy, including diagnosis,
treatment planning, treatment monitoring, and surgical planning.Comment: 15 pages, 4 figures, 9 tables, pre-print submitted to Medical Physics
- dataset. The training dataset is available on Zenodo at
https://doi.org/10.5281/zenodo.7260705 from April, 1st 202
Predictive validity of the UK clinical aptitude test in the final years of medical school:a prospective cohort study
Peer reviewedPublisher PD
Individual variation in levels of haptoglobin-related protein in children from Gabon
Background: Haptoglobin related protein (Hpr) is a key component of trypanosome lytic factors (TLF), a subset of highdensity lipoproteins (HDL) that form the first line of human defence against African trypanosomes. Hpr, like haptoglobin (Hp) can bind to hemoglobin (Hb) and it is the Hpr-Hb complexes which bind to these parasites allowing uptake of TLF. This unique form of innate immunity is primate-specific. To date, there have been no population studies of plasma levels of Hpr, particularly in relation to hemolysis and a high prevalence of ahaptoglobinemia as found in malaria endemic areas. Methods and Principal Findings: We developed a specific enzyme-linked immunosorbent assay to measure levels of plasma Hpr in Gabonese children sampled during a period of seasonal malaria transmission when acute phase responses (APR), malaria infection and associated hemolysis were prevalent. Median Hpr concentration was 0.28 mg/ml (range 0.03-1.1). This was 5-fold higher than that found in Caucasian children (0.049 mg/ml, range 0.002-0.26) with no evidence of an APR. A general linear model was used to investigate associations between Hpr levels, host polymorphisms, parasitological factors and the acute phase proteins, Hp, C-reactive protein (CRP) and albumin. Levels of Hpr were associated with Hp genotype, decreased with age and were higher in females. Hpr concentration was strongly correlated with that of Hp, but not CRP
Hysteresis phenomenon in turbulent convection
Coherent large-scale circulations of turbulent thermal convection in air have
been studied experimentally in a rectangular box heated from below and cooled
from above using Particle Image Velocimetry. The hysteresis phenomenon in
turbulent convection was found by varying the temperature difference between
the bottom and the top walls of the chamber (the Rayleigh number was changed
within the range of ). The hysteresis loop comprises the one-cell
and two-cells flow patterns while the aspect ratio is kept constant (). We found that the change of the sign of the degree of the anisotropy of
turbulence was accompanied by the change of the flow pattern. The developed
theory of coherent structures in turbulent convection (Elperin et al. 2002;
2005) is in agreement with the experimental observations. The observed coherent
structures are superimposed on a small-scale turbulent convection. The
redistribution of the turbulent heat flux plays a crucial role in the formation
of coherent large-scale circulations in turbulent convection.Comment: 10 pages, 9 figures, REVTEX4, Experiments in Fluids, 2006, in pres
- …