Dynamics Of Twinning In Natural Α-quartz

Finite amplitude internal friction experiments in α-quartz are described and interpreted in terms of the theory of nonlinear anelasticity. The theory predicts a linear relationship between the driving force of the excitation and the period of the auto modulation at its onset. This relation is substantiated by experiments performed with a natural α-quartz reed vibrating in flexure at resonance frequencies between 65 and 170 Hz in the temperature range of 162° and 224°C. The data suggests that Dauphiné twinning in α-quartz causes the auto modulation governed by an activation energy of 92 kJ mole. This activation energy characterizes short distance oxygen diffusion. © 1984

Nonlinear Anelasticity Of Magnesium

An approximate solution of the equation of motion of a nonlinear anelastic reed at or near resonance is presented. The steady state solution reproduces the well-known nonlinear resonances. The solution also predicts the existence of auto modulations, i.e., self-excited modulations of the amplitude and phase at constant power of excitation of the reed. Numerical examples of such auto modulations are presented for an antisymmetric deformation potential. Experimental studies of finite amplitude oscillations of a magnesium reed vibrating at 72 and 431 Hz at room temperature confirm the existence of auto modulations. The experimental results can be semi quantitatively described in terms of the solution given. The assumption that finite deformation by twinning represents the essential nonlinearity leads to a self-consistent interpretation. The relaxation time of twinning is obtained from the analysis of the auto modulation and is 22 msec in the sample investigated. It is proposed that point defects control the relaxation process

p53 Maintains Genomic Stability by Preventing Interference between Transcription and Replication

10.1016/j.celrep.2016.03.011CELL REPORTS151132-14

p53 Maintains Genomic Stability by Preventing Interference between Transcription and Replication

p53 tumor suppressor maintains genomic stability, typically acting through cell-cycle arrest, senescence, and apoptosis. We discovered a function of p53 in preventing conflicts between transcription and replication, independent of its canonical roles. p53 deficiency sensitizes cells to Topoisomerase (Topo) II inhibitors, resulting in DNA damage arising spontaneously during replication. Topoisomerase IIα (TOP2A)-DNA complexes preferentially accumulate in isogenic p53 mutant or knockout cells, reflecting an increased recruitment of TOP2A to regulate DNA topology. We propose that p53 acts to prevent DNA topological stress originating from transcription during the S phase and, therefore, promotes normal replication fork progression. Consequently, replication fork progression is impaired in the absence of p53, which is reversed by transcription inhibition. Pharmacologic inhibition of transcription also attenuates DNA damage and decreases Topo-II-DNA complexes, restoring cell viability in p53-deficient cells. Together, our results demonstrate a function of p53 that may underlie its role in tumor suppression

Premartensitic anelasticity in indium-thallium alloys

The linear and nonlinear low frequency internal friction of In-24 at. pct Tl displays a Curie-Weiss type behavior in the temperature range above the transformation temperature. The critical temperature equals the martensite start temperature. It is proposed that the origin of the observed internal friction is the diffusion-controlled interaction of substitutional atoms with the premartensitic strain modulation, tweed

Optimising the use of the prostate- specific antigen blood test in asymptomatic men for early prostate cancer detection in primary care: report from a UK clinical consensus

Screening is not recommended for prostate cancer in the UK. Asymptomatic men aged ≥50 years can request a prostate-specific antigen (PSA) test following counselling on potential harms and benefits. There are areas of clinical uncertainty among GPs, resulting in the content and quality of counselling varying. To produce a consensus that can influence guidelines for UK primary care on the optimal use of the PSA test in asymptomatic men for early prostate cancer detection. Prostate Cancer UK facilitated a RAND/UCLA consensus. Statements covering five topics were developed with a subgroup of experts. A panel of 15 experts in prostate cancer scored (round one) statements on a scale of one (strongly disagree) to nine (strongly agree). Panellists met to discuss statements before rescoring (round two). A lived experience panel of seven men scored a subset of statements with outcomes fed into the main panel. Of the initial 94 statements reviewed by the expert panel, a final 48/85 (56%) achieved consensus. In the absence of screening, there was consensus on proactive approaches to initiate discussions about the PSA test with men who were at higher-than-average risk. Improvements in the prostate cancer diagnostic pathway may have reduced some of the harms associated with PSA testing; however, several areas of uncertainty remain in relation to screening, including optimal PSA thresholds for referral and intervals for retesting. There is consensus on proactive approaches to testing in higher-than-average risk groups. This should prompt a review of current guidelines