2,932 research outputs found
The effect of variable labels on deep learning models trained to predict breast density
Purpose: High breast density is associated with reduced efficacy of
mammographic screening and increased risk of developing breast cancer. Accurate
and reliable automated density estimates can be used for direct risk prediction
and passing density related information to further predictive models. Expert
reader assessments of density show a strong relationship to cancer risk but
also inter-reader variation. The effect of label variability on model
performance is important when considering how to utilise automated methods for
both research and clinical purposes. Methods: We utilise subsets of images with
density labels to train a deep transfer learning model which is used to assess
how label variability affects the mapping from representation to prediction. We
then create two end-to-end deep learning models which allow us to investigate
the effect of label variability on the model representation formed. Results: We
show that the trained mappings from representations to labels are altered
considerably by the variability of reader scores. Training on labels with
distribution variation removed causes the Spearman rank correlation
coefficients to rise from to either when
averaging across readers or when averaging across images.
However, when we train different models to investigate the representation
effect we see little difference, with Spearman rank correlation coefficients of
and showing no statistically significant
difference in the quality of the model representation with regard to density
prediction. Conclusions: We show that the mapping between representation and
mammographic density prediction is significantly affected by label variability.
However, the effect of the label variability on the model representation is
limited
Bite force and cranial bone strain in four species of lizards
In vivo bone strain data provide direct evidence of strain patterns in the cranium during biting. Compared to mammals, in vivo bone strains in lizard skulls are poorly documented. This paper presents strain data from the skulls of Anolis equestris, Gekko gecko, Iguana iguana and Salvator merianae during transducer biting. Analysis of variance was used to investigate effects of bite force, bite point, diet, cranial morphology and cranial kinesis on strain magnitudes. Within individuals the most consistent determinants of variance in bone strain magnitudes are gage location and bite point, with the importance of bite force varying between individuals. Inter-site variance in strain magnitudesâstrain gradientâis present in all individuals, and varies with bite point. Between individuals within species, variance in strain magnitude is driven primarily by variation in bite force, not gage location or bite point, suggesting that inter-individual variation in patterns of strain magnitude is minimal. Between species, variation in strain magnitudes is significantly impacted by bite force and species membership, as well as by interactions between gage location, species, and bite point. Independent of bite force, species differences in cranial strain magnitudes may reflect selection for different cranial morphology in relation to feeding function, but what these performance criteria are is not clear. The relatively low strain magnitudes in Iguana and Uromastyx compared to other lizards may be related to their herbivorous diet. Cranial kinesis and the presence or absence of postorbital and supratemporal bars are not important determinants of inter-specific variation in strain magnitudes
The comorbidities of dysmenorrhea: a clinical survey comparing symptom profile in women with and without endometriosis
Purpose: Dysmenorrhea is a common disorder that substantially disrupts the lives of young women. The frequency of 14 associated symptoms both within and outside the pelvis was determined.
Patients and methods: Symptom questionnaires were completed by 168 women with dysmenorrhea, allocated to three groups based on their diagnostic status for endometriosis confirmed (Endo+), endometriosis excluded (Endoâ), or endometriosis diagnosis unknown (No Lap). Those with endometriosis confirmed were further divided into current users (Endo+ Hx+) and non-users of hormonal treatments (Endo+ Hxâ). Users of hormonal treatments were further divided into users (Endo+ Hx+ LIUCD+) and non-users (Endo+ Hx+ LIUCDâ) of a levonorgestrel-releasing intra-uterine contraceptive device (LIUCD). The frequency and number of symptoms within groups and the effect of previous distressing sexual events were sought.
Results: Women with and without endometriosis lesions had similar symptom profiles, with a mean of 8.5 symptoms per woman. Only 0.6% of women reported dysmenorrhea alone. The presence of stabbing pelvic pains was associated with more severe dysmenorrhea (P=0.006), more days per month of dysmenorrhea (P=0.003), more days per month of pelvic pain (P=0.016), and a diagnosis of migraine (P=0.054). The symptom profiles of the Endo+ Hx+ and Endo+ Hxâ groups were similar. A history of distressing sexual events was associated with an increased number of pain symptoms (P=0.003).
Conclusion: Additional symptoms are common in women with dysmenorrhea, and do not correlate with the presence or absence of endometriosis lesions. Our study supports the role of central sensitization in the pain of dysmenorrhea. The presence of stabbing pelvic pains was associated with increased severity of dysmenorrhea, days per month of dysmenorrhea, days per month of pelvic pain, and a diagnosis of migraine headache. A past history of distressing sexual events is associated with an increased number of pain symptoms
Latent Constructs in Psychosocial Factors Associated with Cardiovascular Disease: An Examination by Race and Sex
This study examines race and sex differences in the latent structure of 10 psychosocial measures and the association of identified factors with self-reported history of coronary heart disease (CHD). Participants were 4,128 older adults from the Chicago Health and Aging Project. Exploratory factor analysis (EFA) with oblique geomin rotation was used to identify latent factors among the psychosocial measures. Multi-group comparisons of the EFA model were conducted using exploratory structural equation modeling to test for measurement invariance across race and sex subgroups. A factor-based scale score was created for invariant factor(s). Logistic regression was used to test the relationship between the factor score(s) and CHD adjusting for relevant confounders. Effect modification of the relationship by raceâsex subgroup was tested. A two-factor model fit the data well (comparative fit indexâ=â0.986; TuckerâLewis indexâ=â0.969; root mean square error of approximationâ=â0.039). Depressive symptoms, neuroticism, perceived stress, and low life satisfaction loaded on Factor I. Social engagement, spirituality, social networks, and extraversion loaded on Factor II. Only Factor I, re-named distress, showed measurement invariance across subgroups. Distress was associated with a 37% increased odds of self-reported CHD (odds ratio: 1.37; 95% confidence intervals: 1.25, 1.50; p-valueâ<â0.0001). This effect did not differ by race or sex (interaction p-valueâ=â0.43). This study identified two underlying latent constructs among a large range of psychosocial variables; only one, distress, was validly measured across raceâsex subgroups. This construct was robustly related to prevalent CHD, highlighting the potential importance of latent constructs as predictors of cardiovascular disease
Moving beyond physical education subject knowledge to develop knowledgeable teachers of the subject
All knowledge is socially constructed, including physical education teachersâ knowledge of their subject. It is acquired from other people either formally and deliberately (e.g. by being taught) or informally and casually (e.g. by interacting with physical education teachers or playing in a sports team). The social aspects of learning appear to be particularly strong in physical education. This has implications for the development of knowledge for teaching, with trainee teachers focusing on the development of subject, and particularly content, knowledge. Focusing on subject knowledge reinforces a traditional view of physical education as it is, not as it might be to meet the needs of young people today. It is argued that attention needs to be given not only to the knowledge, skills and competencies that trainee teachers ought to develop but also to the social aspects of their learning and development and the context in which they learn. Attention also needs to be given to how the ability to think critically can be developed so that trainee teachers can become reflective practitioners able to challenge and, where appropriate, change the teaching of the subject. Only by doing this can the particularly strong socialisation which shapes the values and beliefs of physical education teachers begin to be challenged. However, as the process of developing knowledgeable teachers is ongoing it is also necessary to look beyond teacher training to continuing professional development
Moving beyond physical education subject knowledge to develop knowledgeable teachers of the subject
All knowledge is socially constructed, including physical education teachersâ knowledge of their subject. It is acquired from other people either formally and deliberately (e.g. by being taught) or informally and casually (e.g. by interacting with physical education teachers or playing in a sports team). The social aspects of learning appear to be particularly strong in physical education. This has implications for the development of knowledge for teaching, with trainee teachers focusing on the development of subject, and particularly content, knowledge. Focusing on subject knowledge reinforces a traditional view of physical education as it is, not as it might be to meet the needs of young people today. It is argued that attention needs to be given not only to the knowledge, skills and competencies that trainee teachers ought to develop but also to the social aspects of their learning and development and the context in which they learn. Attention also needs to be given to how the ability to think critically can be developed so that trainee teachers can become reflective practitioners able to challenge and, where appropriate, change the teaching of the subject. Only by doing this can the particularly strong socialisation which shapes the values and beliefs of physical education teachers begin to be challenged. However, as the process of developing knowledgeable teachers is ongoing it is also necessary to look beyond teacher training to continuing professional development
Detection Of KOI-13.01 Using The Photometric Orbit
We use the KOI-13 transiting star-planet system as a test case for the
recently developed BEER algorithm (Faigler & Mazeh 2011), aimed at identifying
non-transiting low-mass companions by detecting the photometric variability
induced by the companion along its orbit. Such photometric variability is
generated by three mechanisms, including the beaming effect, tidal ellipsoidal
distortion, and reflection/heating. We use data from three Kepler quarters,
from the first year of the mission, while ignoring measurements within the
transit and occultation, and show that the planet's ephemeris is clearly
detected. We fit for the amplitude of each of the three effects and use the
beaming effect amplitude to estimate the planet's minimum mass, which results
in M_p sin i = 9.2 +/- 1.1 M_J (assuming the host star parameters derived by
Szabo et al. 2011). Our results show that non-transiting star-planet systems
similar to KOI-13.01 can be detected in Kepler data, including a measurement of
the orbital ephemeris and the planet's minimum mass. Moreover, we derive a
realistic estimate of the amplitudes uncertainties, and use it to show that
data obtained during the entire lifetime of the Kepler mission, of 3.5 years,
will allow detecting non-transiting close-in low-mass companions orbiting
bright stars, down to the few Jupiter mass level. Data from the Kepler Extended
Mission, if funded by NASA, will further improve the detection capabilities.Comment: Accepted to AJ on October 4, 2011. Kepler Q5 Long Cadence data will
become publicly available on MAST by October 23. Comments welcome (V2: minor
changes, to reflect proof corrections
Once a feminist: Lynne Segal on Grace Paleyâs The Little Disturbances of Man
The following contributions came in response to a request, sent to a number of key figures in feminism today, to write on a text that had been formative for their thinking as feminists. The chosen text could be a theory, a novel, an artwork, a performance, a poem: one that had stimulated, or even revolutionised, their ideas. As we hoped, this project has created a selection of texts central to our many and different experiences as feminists.
I used to say that Margaret Drabble's The Garrick Year was the story of my life, in my early twenties, as if I was just a creature of time and circumstance. I read The Garrick Year sometime between October 1965, when my first child was born, and the end of 1967, before my marriage disintegrated. Like the heroine Emma Evans, I married a successful actor, had a child, and followed his careerâwhich in the novel led Emma to Hereford for a summer season of plays
Comparative cranial biomechanics in two lizard species: impact of variation in cranial design
Cranial morphology in lepidosaurs is highly disparate and characterised by the frequent loss or reduction of bony elements. In varanids and geckos, the loss of the postorbital bar is associated with changes in skull shape, but the mechanical principles underlying this variation remain poorly understood. Here, we sought to determine how the overall cranial architecture and the presence of the postorbital bar relate to the loading and deformation of the cranial bones during biting in lepidosaurs. Using computer-based simulation techniques, we compared cranial biomechanics in the varanid Varanus niloticus and the teiid Salvator merianae, two large, active foragers. The overall strain magnitude and distribution across the cranium were similar in the two species, despite lower strain gradients in V. niloticus. In S. merianae, the postorbital bar is important for resistance of the cranium to feeding loads. The postorbital ligament, which in varanids partially replaces the postorbital bar, does not affect bone strain. Our results suggest that the reduction of the postorbital bar impaired neither biting performance nor the structural resistance of the cranium to feeding loads in V. niloticus. Differences in bone strain between the two species might reflect demands imposed by feeding and non-feeding functions on cranial shape. Beyond variation in cranial bone strain related to species-specific morphological differences, our results reveal that similar mechanical behaviour is shared by lizards with distinct cranial shapes. Contrary to the situation in mammals, the morphology of the circumorbital region, calvaria and palate appears to be important for withstanding high feeding loads in these lizards
- âŠ