Search Results (5)

TBF 1180 steel was plastically deformed under different strain paths in order to study both the ductility and RA transformation rates. Specimens were prepared from a 1 mm thick sheet and then tested incrementally under uniaxial tension, plane-strain tension, and biaxial tension. The retained austenite (RA) levels were measured, as a function of the plastic strain, using electron backscatter diffraction (EBSD). The plane-strain tension specimens had the fastest rate of RA transformation as a function of strain, followed by uniaxial tension, and then biaxial tension. The forming limits were measured for each strain path, yielding major limit strains of 0.12 under uniaxial tension, 0.09 under plane-strain tension, and 0.16 under biaxial tension. These results were compared to prior work on a 1.2 mm Q&P 1180 steel sheet, which had a similar yield and ultimate tensile strength, but exhibited slightly greater forming limits than the TBF material. The visual inspection of the micrographs appeared to show an equiaxed RA morphology in the Q&P 1180 steel and a mixture of equiaxed and lamellar RA grains in the TBF 1180 steel. However, the statistics generated by EBSD revealed that both alloys had RA grains with essentially the same aspect ratios. The average RA grain size in the Q&P alloy was found to be about three times larger than that of the TBF alloy. As such, the small but consistent formability advantage exhibited by the Q&P 1180 alloy along all three strain paths can be attributed to its larger average RA grain size, where larger RA grain sizes correlated with a more gradual transformation rate. Full article

Spine metastases (SMs) are common, arising in 70% of the cases of the most prevalent malignancies in males (prostate cancer) and females (breast cancer). Stereotactic body radiotherapy, or SBRT, has been incorporated into clinical treatment algorithms over the past decade. SBRT has shown promising rates of local control for oligometastatic spinal lesions with low radiation dose to adjacent critical tissues, particularly the spinal cord. Imaging is critically important in SBRT planning, guidance, and response monitoring. This paper reviews the roles of imaging in spine SBRT, including conventional and advanced imaging approaches for SM detection, treatment planning, and post-SBRT follow-up. Full article

Genomic risk prediction models for breast cancer (BC) have been predominantly developed with data from women aged 40–69 years. Prospective studies of older women aged ≥70 years have been limited. We assessed the effect of a 313-variant polygenic risk score (PRS) for BC in 6339 older women aged ≥70 years (mean age 75 years) enrolled into the ASPREE trial, a randomized double-blind placebo-controlled clinical trial investigating the effect of daily 100 mg aspirin on disability-free survival. We evaluated incident BC diagnoses over a median follow-up time of 4.7 years. A multivariable Cox regression model including conventional BC risk factors was applied to prospective data, and re-evaluated after adding the PRS. We also assessed the association of rare pathogenic variants (PVs) in BC susceptibility genes (BRCA1/BRCA2/PALB2/CHEK2/ATM). The PRS, as a continuous variable, was an independent predictor of incident BC (hazard ratio (HR) per standard deviation (SD) = 1.4, 95% confidence interval (CI) 1.3–1.6) and hormone receptor (ER/PR)-positive disease (HR = 1.5 (CI 1.2–1.9)). Women in the top quintile of the PRS distribution had over two-fold higher risk of BC than women in the lowest quintile (HR = 2.2 (CI 1.2–3.9)). The concordance index of the model without the PRS was 0.62 (95% CI 0.56–0.68), which improved after addition of the PRS to 0.65 (95% CI 0.59–0.71). Among 41 (0.6%) carriers of PVs in BC susceptibility genes, we observed no incident BC diagnoses. Our study demonstrates that a PRS predicts incident BC risk in women aged 70 years and older, suggesting potential clinical utility extends to this older age group. Full article

Violence against women and girls remains a major public health threat the world over. A significant amount of violence experienced by women is perpetrated by their intimate partners. Moreover, the risk of experiencing intimate partner violence is amplified for women and girls who get married before turning 18. However, there is little documented information on how they escape such violent relationships. This article provides insight into the factors that help survivors of child marriage to leave violent relationships. It is based on in-depth interviews with 26 Ugandan women who married before they were 18. Four main factors helped child marriage survivors to leave violent unions: (1) having a secure base to return to; (2) reaching a tipping point in the relationship; (3) financial independence; and (4) intervention of a significant other. The significance of some factors varied with the age of the survivor at the point of leaving. It is concluded that parental support is a key facilitative factor for leaving violent relationships in the context of child marriage within a low resource setting. Interventions to promote positive parenting may significantly contribute to minimising the proportions of girls trapped in violent unions and incidences of child marriage in the long run. Full article

Tissue conductivity is a biophysical marker of tissue structure and physiology. Present methods of measuring tissue conductivity are limited. Electrical impedance tomography and magnetic resonance electrical impedance tomography rely on passing an external current through the object being imaged, which prevents its use in most human imaging. More recently, tissue conductivity has been determined noninvasively from measurements of the radiofrequency (RF) field used in magnetic resonance imaging (MRI). This technique is promising, but conductivity at higher frequencies is less sensitive to tissue structure. Measuring tissue conductivity noninvasively at low frequencies remains elusive. It has been proposed that eddy currents generated during the rise and decay of gradient pulses could act as a current source to map low-frequency conductivity. This work centers on a gradient echo pulse sequence that uses large gradients before excitation to create eddy currents. The electric and magnetic fields during a gradient pulse are simulated by a finite-difference timedomain simulation. The sequence is also tested with a phantom and animal MRI scanner equipped with gradients of high gradient strengths and slew rates. The simulation demonstrates that eddy currents in materials with a conductivity similar to biological tissue decay with a half-life on the order of nanoseconds, and any eddy currents generated before excitation decay completely before influencing the RF signal. Gradient-induced eddy currents can influence phase accumulation after excitation, but the effect is too small to image. The animal scanner images show no measurable phase accumulation. Measuring low-frequency conductivity by gradient-induced eddy currents is presently unfeasible. Full article