336 research outputs found
An investigation of the natural history of early cervical human papillomavirus infection and its relationship to the acquisition of epithelial abnormalities of the cervix
Cervical human papillomavirus (HPV) infection is a very common sexually transmitted disease which is now considered to be a necessary, but not sufficient, cause of cervical cancer. It has been suggested that the association between HPV infection and cervical neoplasia can be exploited to improve the efficiency and effectiveness of primary- and secondary-prevention programmes for cervical cancer. However, whether this aspiration can be realized in practice requires a greater understanding of the natural history of early cervical HPV infection and its role in the acquisition of epithelial abnormalities of the cervix. In this thesis, a longitudinal study of young women who had recently embarked on sexual activity has provided sequential observations on the natural history of cervical HPV infection. This thesis addresses four aspects of this natural history: the association between HPV infection and the proximity of first sexual intercourse to menarche; the association between smoking, cervical HPV infection and high-grade cervical disease; the validation of a neutralising antibody assay and its use in defining the kinetics of the humoral immune response to cervical HPV16 and HPV18 infections; and the analysis of measurements of the viral load of HPV16 and HPV18, and their association with epithelial abnormalities of the cervi
The 2dF Galaxy Redshift Survey: spectral types and luminosity functions
We describe the 2dF Galaxy Redshift Survey (2dFGRS) and the current status of the observations. In this exploratory paper, we apply a principal component analysis to a preliminary sample of 5869 galaxy spectra and use the two most significant components to split the sample into five spectral classes. These classes are defined by considering visual classifications of a subset of the 2dF spectra, and also by comparison with high-quality spectra of local galaxies. We calculate a luminosity function for each of the different classes and find that later-type galaxies have a fainter characteristic magnitude, and a steeper faint-end slope. For the whole sample we find M*=−19.7 (for Ω=1, H₀=100 km s⁻¹ Mpc⁻¹), α=−1.3, φ*=0.017. For class 1 (‘early-type’) we find M*=−19.6, α=−0.7, while for class 5 (‘late-type’) we find M*=−19.0, α=−1.7. The derived 2dF luminosity functions agree well with other recent luminosity function estimates
Alcohol consumption and lifetime change in cognitive ability:a gene × environment interaction study
Studies of the effect of alcohol consumption on cognitive ability are often confounded. One approach to avoid confounding is the Mendelian randomization design. Here, we used such a design to test the hypothesis that a genetic score for alcohol processing capacity moderates the association between alcohol consumption and lifetime change in cognitive ability. Members of the Lothian Birth Cohort 1936 completed the same test of intelligence at age 11 and 70 years. They were assessed for recent alcohol consumption in later life and genotyped for a set of four single-nucleotide polymorphisms in three alcohol dehydrogenase genes. These variants were unrelated to late-life cognition or to socioeconomic status. We found a significant gene × alcohol consumption interaction on lifetime cognitive change (p = 0.007). Individuals with higher genetic ability to process alcohol showed relative improvements in cognitive ability with more consumption, whereas those with low processing capacity showed a negative relationship between cognitive change and alcohol consumption with more consumption. The effect of alcohol consumption on cognitive change may thus depend on genetic differences in the ability to metabolize alcohol
What is missing in autonomous discovery: Open challenges for the community
Self-driving labs (SDLs) leverage combinations of artificial intelligence,
automation, and advanced computing to accelerate scientific discovery. The
promise of this field has given rise to a rich community of passionate
scientists, engineers, and social scientists, as evidenced by the development
of the Acceleration Consortium and recent Accelerate Conference. Despite its
strengths, this rapidly developing field presents numerous opportunities for
growth, challenges to overcome, and potential risks of which to remain aware.
This community perspective builds on a discourse instantiated during the first
Accelerate Conference, and looks to the future of self-driving labs with a
tempered optimism. Incorporating input from academia, government, and industry,
we briefly describe the current status of self-driving labs, then turn our
attention to barriers, opportunities, and a vision for what is possible. Our
field is delivering solutions in technology and infrastructure, artificial
intelligence and knowledge generation, and education and workforce development.
In the spirit of community, we intend for this work to foster discussion and
drive best practices as our field grows
The 2dF galaxy redshift survey: clustering properties of radio galaxies
The clustering properties of local, S1.4 GHz≥ 1 mJy, radio sources are investigated for a sample of 820 objects drawn from the joint use of the Faint Images of the Radio Sky at 20 cm (FIRST) and 2dF Galaxy Redshift surveys. To this aim, we present 271 new bJ≤ 19.45 spectroscopic counterparts of FIRST radio sources to be added to those already introduced in our previous paper. The two-point correlation function for the local radio population is found to be entirely consistent with estimates obtained for the whole sample of 2dFGRS galaxies. From measurements of the redshift-space correlation function ξ(s) we derive a redshift-space clustering length s0 = 10.7+0.8 −0.7 Mpc, while from the projected correlation function Ξ(rT) we estimate the parameters of the real-space correlation function ξ(r) = (r/r0) −γ, r0 = 6.7+0.9 −1.1 Mpc and γ= 1.6 ± 0.1, where h = 0.7 is assumed. Different results are instead obtained if we only consider sources that present signatures of active galactic nucleus (AGN) activity in their spectra. These objects are shown to be very strongly correlated, with r0 = 10.9+1.0 −1.2 Mpc and γ= 2 ± 0.1, a steeper slope than has been claimed in other recent works. No difference is found in the clustering properties of radio-AGNs of different radio luminosity. Comparisons with models for ξ(r) show that AGN-fuelled sources reside in dark matter haloes more massive than ∼1013.4 M⊙, higher than the corresponding figure for radio-quiet quasi-stellar objects. This value can be converted into a minimum black hole mass associated with radio-loud, AGN-fuelled objects of MminBH∼ 109 M⊙. The above results then suggest - at least for relatively faint radio objects - the existence of a threshold black hole mass associated with the onset of significant radio activity such as that of radio-loud AGNs; however, once the activity is triggered, there appears to be no evidence for a connection between black hole mass and level of radio outpu
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